US20130085331A1 - System and method for selective measurement of fiber optic instrument sensors - Google Patents

Abstract

An instrument system that includes an elongate body, an optical fiber, and a controller is provided. The optical fiber is operatively coupled to the elongate body and has a plurality of strain sensors provided on the optical fiber. The controller is operatively coupled to the optical fiber and adapted to obtain signals from one of the plurality of strain sensors more frequently than from another of the plurality of strain sensors and to determine a position of the elongate body based on the obtained signals from the one of the plurality of strain sensors.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• The present application is a divisional of U.S. patent application Ser. No. 12/192,033 filed on Aug. 14, 2008, which claims the benefit under 35 U.S.C. §119 to U.S. Provisional Application No. 60/964,773, filed on Aug. 14, 2007, the contents of which is incorporated herein by reference as though set forth in full.
• The present application may also be related to subject matter disclosed in the following applications, the contents of which are also incorporated herein by reference as though set forth in full: U.S. patent application Ser. No. 10/923,660, entitled “System and Method for 3-D Imaging”, filed Aug. 20, 2004; U.S. patent application Ser. No. 10/949,032, entitled “Balloon Visualization for Transversing a Tissue Wall”, filed Sep. 24, 2005; U.S. patent application Ser. No. 11/073,363, entitled “Robotic Catheter System”, filed Mar. 4, 2005; U.S. patent application Ser. No. 11/173,812, entitled “Support Assembly for Robotic Catheter Assembly”, filed Jul. 1, 2005; U.S. patent application Ser. No. 11/176,954, entitled “Instrument Driver for Robotic Catheter System”, filed Jul. 6, 2005; U.S. patent application Ser. No. 11/179,007, entitled “Methods Using A Robotic Catheter System”, filed Jul. 6, 2005; U.S. patent application Ser. No. 11/185,432, entitled “System and method for denaturing and fixing collagenous tissue”, filed Jul. 19, 2005; U.S. patent application Ser. No. 11/202,925, entitled “Robotically Controlled Intravascular Tissue Injection System”, filed Aug. 12, 2005; U.S. patent application Ser. No. 11/331,576, entitled “Robotic Catheter System”, filed Jan. 13, 2006; U.S. patent application Ser. No. 11/418,398, entitled “Robotic Catheter System”, filed May 3, 2006; U.S. patent application Ser. No. 11/481,433, entitled “Robotic Catheter System and Methods”, filed Jul. 3, 2006; U.S. patent application Ser. No. 11/637,951, entitled “Robotic Catheter System and Methods”, filed. Dec. 11, 2006; U.S. patent application Ser. No. 11/640,099, entitled “Robotic Catheter System and Methods”, filed Dec. 14, 2006; U.S. patent application Ser. No. 11/678,001, entitled Apparatus for Measuring Distal Forces on a Working Instrument, filed Feb. 22, 2007; U.S. patent application Ser. No. 11/678,016, entitled Method of Sensing Forces on a Working Instrument, filed Feb. 22, 2007; U.S. patent application Ser. No. 11/690,116, entitled Fiber Optic Instrument Sensing System, filed Mar. 22, 2007; U.S. patent application Ser. No. 12/032,622, entitled Instrument Driver Haying Independently Rotatable Carriages, filed Feb. 15, 2008; U.S. patent application Ser. No. 12/032,634, entitled Support Structure :for Robotic Medical Instrument filed Feb. 15, 2008; U.S. patent application Ser. No. 12/032,626, entitled Instrument Assembly for Robotic Instrument System, filed Feb. 15, 2008; U.S. patent application Ser. No. 12/032,639, entitled Flexible Catheter Instruments and Methods, filed Feb. 15, 2008; U.S. application Ser. No. 12/106,254, entitled Optical Fiber Shape Sensing Systems, filed on Apr. 18, 2008; and U.S. application Ser. No. 12/114,720, entitled Apparatus, Systems and Methods for I-Twining a Working Platform of a Robotic instrument System by Manipulation of Components Having Controllable Rigidity,” filed on May 2, 2008.
• The present application may also be related to subject matter disclosed in the following provisional applications, the contents of which are also incorporated herein by reference as though set forth in full: U.S. Provisional Patent Application No. 60/550,961, entitled “Robotic Catheter System,” filed Mar. 5, 2004; U.S. Provisional Patent Application No. 60/750,590, entitled “Robotic Catheter System and Methods”, filed Dec. 14, 2005; U.S. Provisional Patent Application No. 60/756,136, entitled “Robotic Catheter System and Methods”, filed Jan. 3, 2006; U.S. Provisional Patent Application No. 60/776,065, entitled “Force Sensing for Medical Instruments”, filed Feb. 22, 2006; U.S. Provisional Patent Application No. 60/785,001, entitled “Fiberoptic Bragg Grating Medical instrument”, filed Mar. 22, 2006; U.S. Provisional Patent Application No. 60/788,176, entitled “Fiberoptic Bragg Grating Medical Instrument”, filed Mar. 31, 2006; U.S. Provisional Patent Application No. 60/801,355, entitled “Sheath and Guide Catheter Apparatuses For A Robotic Catheter System With Force Sensing”, filed May 17, 2006; U.S. Provisional Patent Application No. 60/801,546, entitled “Robotic Catheter System and Methods”, filed May 17, 2006; U.S. Provisional Patent Application No. 60/801,945, entitled “Robotic Catheter System and Methods”, filed May 18, 2006; U.S. Provisional Patent Application No. 60/833,624, entitled “Robotic Catheter System and Methods”, filed Jul. 26, 2006; U.S. Provisional Patent Application No. 60/835,592, entitled “Robotic Catheter System and Methods”, filed Aug. 3, 2006; U.S. Provisional Patent Application No. 60/838,075, entitled “Robotic Catheter System and Methods”, filed Aug. 15, 2006; U.S. Provisional Patent Application No. 60/840,331, entitled “Robotic Catheter System and Methods”, filed Aug. 24, 2006; U.S. Provisional Patent Application No. 60/843,274, entitled “Robotic Catheter System and Methods”, filed Sep. 8, 2006; U.S. Provisional Patent Application No. 60/873,901, entitled “Robotic Catheter System and Methods”, filed Dec. 8, 2006; U.S. Provisional Patent Application No. 60/879,911, entitled “Robotic Catheter System and Methods”, filed Jan. 10, 2007; U.S. Provisional Patent Application No. 60/899,048, entitled “Robotic Catheter System”, filed Feb. 8, 2007; U.S. Provisional Patent Application No. 60/900,584, entitled “Robotic Catheter System and Methods”, filed Feb. 8, 2007; U.S. Provisional Patent Application No. 60/902,144, entitled, Flexible Catheter Instruments and Methods, filed on Feb. 15, 2007; U.S. Provisional Patent Application No. 60/925,449, entitled Optical Fiber Shape Sensing Systems, filed Apr. 20, 2007; and U.S. Provisional Patent Application No. 60/925,472, entitled Systems and Methods for Processing Shape Sensing Data, filed Apr. 20, 2007.
FIELD OF INVENTION
• The invention relates generally to robotically controlled systems such as telerobotic surgical systems.
BACKGROUND
• Robotic interventional al systems and devices are well suited for use in performing minimally invasive medical procedures as opposed. to conventional procedures that involve opening the patient's body to permit the surgeon's hands to access internal organs. Traditionally, surgery utilizing conventional procedures meant significant pain, long recovery times, lengthy work absences, and visible scarring. However, advances in technology have led to significant changes in the field of medical surgery such that less invasive surgical procedures are increasingly popular, in particular, minimally invasive surgery (MIS). A “minimally invasive medical procedure” is generally considered a procedure that is performed by entering the body through the skin, a body cavity, or an anatomical opening utilizing small incisions rather than larger, more invasive open incisions in the body.
• Various medical procedures are considered to be minimally invasive including, for example, mitral and tricuspid valve procedures, patent formen ovale, atrial septal defect surgery, colon and rectal surgery, laparoscopic appendectomy, laparoscopic esophagectomy, laparoscopic hysterectomies, carotid angioplasty, vertebroplasty, endoscopic sinus surgery, thoracic surgery, donor nephrectomy, hypodermic injection, air-pressure injection, subdermal implants, endoscopy, percutaneous surgery, laparoscopic surgery, arthroscopic surgery, cryosurgery, microsurgery, biopsies, videoscope procedures, keyhole surgery, endovascular surgery, coronary catheterization, permanent spinal and brain electrodes, stereotactic surgery, and radioactivity-based medical imaging methods. With MIS, it is possible to achieve less operative trauma for the patient, reduced hospitalization time, less pain and scarring, reduced incidence of complications related to surgical trauma, lower costs, and a speedier recovery.
• Special medical equipment may be used to perform MIS procedures. Typically, a surgeon inserts small tubes or ports into a patient and uses endoscopes or laparoscopes having a fiber optic camera, light source, or miniaturized surgical instruments. Without a traditional large and invasive incision, the surgeon is not able to see directly into the patient. Thus, the video camera serves as the surgeon's eyes. Images of the body interior are transmitted to an external video monitor to allow a surgeon to analyze the images, make a diagnosis, visually identify internal features, and perform surgical procedures based on the images presented on the monitor.
• MIS procedures may involve minor surgery as well as more complex operations. Such operations may involve robotic and computer technologies, which have led to improved visual magnification, electromechanical stabilization and reduced number of incisions. The integration of robotic technologies with surgeon skill into surgical robotics enables surgeons to perform surgical procedures in new and more effective ways.
• Although MIS techniques have advanced, physical limitations of certain types of medical equipment still have shortcomings and can be improved. For example, during a MIS procedure, catheters (e.g., a sheath catheter, a guide catheter, an ablation catheter, etc.), endoscopes or laparoscopes may be inserted into a body cavity duct or vessel. A catheter is an elongated tube that may, for example, allow for drainage or injection of fluids or provide a path for delivery of working or surgical instruments to a surgical or treatment site. In known robotic instrument systems, however, the ability to control and manipulate system components such as catheters and associated working instruments may be limited due, in part, to a surgeon not having direct access to the target site and not being able to directly handle or control the working instrument at the target site.
• More particularly, MIS diagnostic and interventional operations require the surgeon to remotely approach and address the operation or target site by using instruments that are guided, manipulated and advanced through a natural body orifice such as a blood vessel, esophagus, trachea., small intestine, large intestine, urethra, or a small incision in the body of the patient. In some situations, the surgeon may approach the target site through both a natural body orifice as well as a small incision in the body.
• For example, one or more catheters and other surgical instruments used to treat cardiac arrhythmias such as atrial fibrillation (AR are inserted through an incision at the femoral vein near the thigh or pelvic region of the patient, which is at some distance away from the operation or target site. In this example, the operation or target site for performing cardiac ablation is in the left atrium of the heart. Catheters are guided (e.g., by a guide wire, etc.) manipulated, and advanced toward the target site by way of the femoral vein to the inferior vena cava into the right atrium through the interatrial septum to the left atrium of the heart. The catheters may be used to apply cardiac ablation therapy to the left atrium of the heart to restore normal heart function.
• However, controlling one or more catheters that are advanced through naturally-occurring pathways such as blood vessels or other lumens via surgically-created wounds of minimal size, or both, can be a difficult task. Remotely controlling distal portions of one or more catheters to precisely position system components to treat tissue that may lie deep within a patient, e.g., the left atrium of the heart, can also be difficult. These difficulties are due in part to limited control of movement and articulation of system components, associated limitations on imaging and diagnosis of target tissue, and limited abilities and difficulties of accurately determining the shape and/or position of system components and distal portions thereof within the patient. These limitations can complicate or limit the effectiveness of surgical procedures performed using minimally invasive robotic instrument systems.
• For example, referring toFIG. 1, a typical field of view or display10 of a catheter includes arepresentation12 of a catheter and animage14 of a catheter. Thecatheter representation12 is in the form of “cartoon object” that is created based on a position of the catheter determined according to a kinematics model. Theimage14 is generated using an imaging modality such as fluoroscopy.
• A kinematics model is related to the motion and shape of an instrument, without consideration of forces on the instrument that bring about that motion. In other words, a kinematics model is based on geometric parameters and how a position of the instrument changes relative to a pre-determined or reference position or set of coordinates. One example of a kinematics model that may be used in non-invasive robotic applications receives as an input a desired or selected position of the instrument, e.g., a position of a distal portion of the instrument within a portion of the heart, and outputs a corresponding shape or configuration of the instrument, e.g., with reference to a current or known shape or configuration, that results in positioning of the instrument according to the input.
• A fluoroscopic system may be utilized to image, or “visualize”, the elongate instrument or a portion thereof. A drawback of known fluoroscopic imaging systems is that it they are projection based such that depth information is lost. As a result, true three-dimensional location of objects such as an elongate instrument in the field of view of the fluoroscope is lost as a result of generating a two-dimensional fluoroscopic image. Thus, even if it is possible to obtain accurate x-y or two-dimensional data, it may be difficult or impossible to accurately determine the location of a catheter in three-dimensional space. Examples of fluoroscopy instruments and associated methods are described in further detail in U.S. application Ser. No. 11/637,951, the contents of which were previously incorporated by reference.
• In the example illustrated inFIG. 1, the shapes of therepresentation12 andimage14 are generally consistent, but in some applications, the position and/or shape of a catheter or elongate instrument may differ and inaccurately reflect the shape and/or position of the instrument, which may result in complications during surgical procedures. Such mismatches may be interpreted as a problem associated with the kinematics model or controls or sensing algorithms, or as a result of contact between the subject instrument and a nearby object, such as tissue or another instrument.
• A process called “registration” may be performed to spatially associate the two coordinate systems in three dimensions. Registration involves moving the elongate instrument to one or more positions, imaging the instrument with one or more positions of the fluoroscopic imaging device (e.g., the C-arm), and analyzing the images to deduce the coordinate system of the elongate instrument in relation to the coordinate system of the fluoroscopic imaging device. This process, however, can be tedious, and it is relatively easy for the elongate instrument to go out of alignment relative to the other pertinent coordinate systems.
BRIEF DESCRIPTION OF THE DRAWINGS
• The present disclosure will be readily understood by the following detailed description, taken in conjunction with accompanying drawings, illustrating by way of examples the principles of the present disclosure. The drawings illustrate the design and utility of preferred embodiments of the present disclosure, in which like elements are referred to by like reference symbols or numerals. The objects and elements in the drawings are not necessarily drawn to scale, proportion or precise positional relationship; instead emphasis is focused on illustrating the principles of the present disclosure.
• FIG. 1 generally illustrates a field of view or display that includes a representation of a catheter generated using a kinematics model and an image of a catheter;
• FIG. 2A illustrates a surgical apparatus constructed according to one embodiment includes an optical fiber sensor attached to or integral with an elongate surgical instrument;
• FIG. 2B is a cross-sectional view of an elongate instrument constructed according to one embodiment and that defines a central lumen and a lumen defined through a wall of the catheter in which an optical fiber sensor may be positioned;
• FIG. 3A schematically illustrates a system for use with optical fiber sensors having one or more Fiber Bragg Gratings written or formed therein and that are coupled to or integral with one or more components of a robotic surgical system;
• FIG. 3B illustrates a core of an optical fiber sensor constructed according to one embodiment including multiple, axially spaced Fiber Bragg Gratings;
• FIG. 3C illustrates a core of an optical fiber sensor constructed according to another embodiment that includes sets of Fiber Bragg Gratings having different reflectivities;
• FIGS. 4A-D illustrate different optical fiber configurations or shapes that may interface with a portion of an elongate instrument or catheter to prevent twisting of the fiber, andFIG. 4E illustrates another configuration of an optical fiber sensor that includes off-center core;
• FIG. 5 generally depicts a mismatch between a shape of a representation of a catheter generated by a kinematics model and a shape of an image of a catheter acquired using an imaging modality that can be addressed or prevented with use of optical fiber sensor embodiments;
• FIG. 6 generally depicts how optical fiber sensor embodiments may be utilized to provide a more accurate x-y-z position data of a two-dimensional image of a catheter;
• FIG. 7 generally depicts how optical fiber sensor embodiments may be utilized to provide more accurate x-y-z position data and orientation, roll or twist data of a two-dimensional image of a catheter;
• FIG. 8 is a flow chart of a method of generating and displaying a representation of an instrument body according to one embodiment;
• FIG. 9 is a flow chart of a method of controlling movement of a component of a robotic surgical system based on shape and location information received or derived from light reflected by an optical fiber sensor according to another embodiment;
• FIG. 10 is a flow chart of a method of generating a structural map of a tissue surface utilizing an optical fiber sensor according to another embodiment;
• FIG. 11 illustrates an embodiment in which multiple fibers are coupled to or integral with respective robotically controllable catheters that carry different types of catheters;
• FIG. 12 illustrates another embodiment of a system in which an optical fiber sensor is coupled to or integral with a controller or instrument driver of an elongate instrument;
• FIG. 13 illustrates an embodiment in which optical fiber sensors are coupled to or integral with respective controllers or instrument drivers of respective robotically controllable catheters and coupled to or integral with respective controllable catheters;
• FIG. 14 illustrates another embodiment in which optical fiber sensors are coupled to or integral with elongate instrument bodies such as a catheter and an image capture device;
• FIG. 15 illustrates another embodiment of a system in which an optical fiber sensor is attached or affixed to a patient;
• FIG. 16 is a flow chart of a method of performing a calibration procedure utilizing an optical fiber sensor according to one embodiment;
• FIG. 17 is a flow chart of a method of performing a diagnostic or therapeutic procedure using an instrument calibrated as shown inFIG. 16;
• FIG. 18 illustrates one embodiment of a test fixture suitable for calibration procedures involving an optical fiber sensor;
• FIG. 19 illustrates one embodiment directed to establishing a reference grating or sensor;
• FIG. 20 illustrates one embodiment of a connector for providing slack and a grating or sensor reference;
• FIG. 21 illustrates an apparatus constructed according to another embodiment that is configured to accommodate a grating having a portion of which that is within a sleeve and a portion of which is outside of the sleeve;
• FIGS. 22A-F illustrate a robotic instrument or surgical system in which embodiments of the invention may be implemented, whereinFIG. 22A illustrates a robotic medical instrument system,FIG. 22B illustrates an operator workstation including a master input device and data gloves,FIG. 22C is a block diagram of a system architecture of a robotic medical instrument system in which embodiments may be implemented or with which embodiments may be utilized,FIG. 22D illustrates a setup joint or support assembly of a robotic instrument system with which embodiments may be utilized,FIG. 22E is a rear perspective view of a flexible catheter assembly of a robotic instrument system with which embodiments may be utilized, andFIG. 22F illustrates an instrument driver to which the flexible catheter assembly illustrated inFIG. 22E may be attached and to which an optical fiber sensor may be coupled;
• FIGS. 23A-C are different views of a multi-a sheath catheter having an optical fiber sensor coupled thereto according to on embodiment;
• FIGS. 24A-D are different views of a rotatable apparatus that interfaces with the sheath catheter illustrated inFIGS. 23A-C;
• FIGS. 25A-F are different views of an orientation platform or interface for a working instrument with which rotational apparatus embodiments as shown inFIGS. 24A-D can be utilized;
• FIGS. 26A-B illustrate other configurations of a robotic instrument system in which embodiments may be utilized, whereinFIG. 26A illustrates an embodiment including three multi-segment sheath catheters, each of which has an optical fiber sensor coupled thereto, andFIG. 26B shows the configuration shown inFIG. 26A with an additional optical fiber sensor coupled to an image capture device that extends through the master sheath;
• FIGS. 27-43 illustrate aspects of a control schema, kinematics, actuation coordinates for kinematics, and a block diagram of a system with which embodiments may be implemented or utilized, a sample flowchart of transforming a position vector to a haptic signal, and a block diagram of a system including haptics capability of robotic surgical systems in which embodiments of the invention may be implemented; and
• FIGS. 44-49 illustrate a system and system configuration for visualization of tissue by overlaying images, a schematic for overlaying objects to the display, a distributed system. architecture and hardware and software interfaces of robotic surgical systems which embodiments may be implemented.
SUMMARY OF THE INVENTION
• In accordance with one embodiment, an instrument system that includes an elongate body, an optical fiber, and a controller is provided. The optical fiber is operatively coupled to the elongate body and has a plurality of strain sensors provided on the optical fiber. The controller is operatively coupled to the optical fiber and adapted to obtain signals from one of the plurality of strain sensors more frequently than from another of the plurality of strain sensors and to determine a position of the elongate body based on the obtained signals from the one of the plurality of strain sensors.
• According to another embodiment, an instrument system that includes an elongate body, an optical fiber, and a controller is provided. The optical fiber is operatively coupled to the elongate body and has a plurality of strain sensors provided on the optical fiber. The controller is operatively coupled to the optical fiber and adapted to select a reference strain sensor from among the plurality of strain sensors, to receive signals from the plurality of optical fibers and to determine, based on the signals received from the plurality of strain sensors, a position of the elongate body relative to a position of the reference strain sensor.
• According to yet another embodiment, an instrument system that includes an elongate body, an optical fiber, and a controller is provided. The optical fiber is operatively coupled to the elongate body and has a plurality of strain sensors provided on the optical fiber. The controller is operatively coupled to the optical fiber and adapted to select a measurement strain sensor from among the plurality of strain sensors, to receive a signal from the measurement strain sensor, and to determine, based on the signal, a position of a portion of the elongate body at which the measurement strain sensor is located.
• These and other aspects of the present disclosure, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. In one embodiment, the structural components illustrated can be considered are drawn to scale. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the present disclosure. It shall also be appreciated that the features of one embodiment disclosed herein can be used in other embodiments disclosed herein. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
• Embodiments of the invention are related to systems, apparatus and methods including or involving the use of optical fiber sensors, e.g., Fiber-Bragg sensors, which may be used to provide accurate shape and/or position data of an elongate instrument.
• Referring toFIG. 2A, according to one embodiment, one or more components of a robotically controlledinstrument200 of a robotic surgical system include an optical fiber or fiber sensor215 (referred to as optical fiber sensor or fiber215), which is coupled to, or an integral part of, anelongate instrument body210. Data based on light reflected by gratings of thefiber215 may be used to determine the shape and/or position of the elongate instrument, which may be a catheter, such as a guide catheter. In the illustrated embodiment, the elongate instrument orcatheter210 is a part of a robotically controlledinstrument200 that it utilized to position a bendabledistal end portion211 of thecatheter210 and one or more workinginstruments240 at a target site within a patient. The particular workinginstrument240 employed may depend on the target tissue and manner in which theinstrument200 is inserted or advanced into the patient.
• Theoptical fiber sensor215 can be attached or coupled to an elongate instrument orcatheter210 in various ways. Referring toFIG. 2B, in one embodiment, theoptical fiber sensor215 extends through a central orother lumen217 defined by thecatheter210. According to another embodiment, theoptical fiber sensor215 extends through alumen213 defined through a wall of thecatheter210, i.e., through alumen213 defined between aninner wall214 and anouter wall216 of thecatheter210.FIG. 2B illustrates asingle lumen213 defined within acatheter210 wall to accommodate a singleoptical fiber sensor215 and asingle lumen217, but in other embodiments,multiple lumens213,217 may be defined, and anoptical fiber sensor215 may extend through some or all of themultiple lumens213,217. In other embodiments, theoptical fiber sensors215 can be coupled, bonded or attached to theinner wall214 or to theouter wall215 as appropriate. Theinner wall214 may also define a groove in which afiber215 may be positioned. In yet other embodiments, anoptical fiber sensor215 can be coupled to or integral with anouter surface216 using, for example, a suitable adhesive or bonding agent and/or thefiber215 may be positioned within an aperture or groove that is formed within theouter wall216. Further, theoptical fiber215 can be coupled to a catheter orother instrument210 in such a manner that a portion of theoptical fiber215 is coupled at a known reference location on the proximal potion of theinstrument210.
• For ease of explanation, this specification refers to anoptical fiber sensor215 that is coupled to or integral with acatheter210 or other system component in a non-limiting manner. Thus, while certain figures may illustrate anoptical fiber sensor215 extending along a surface of acatheter210 for ease of illustration, it should be understood that in practice, one or multipleoptical fiber sensors215 may extend through one ormore lumens213,217 of one or more instruments depending on the configuration employed.
• Referring again toFIG. 2A, one manner in which robotic intravascular systems including anelongate instrument210 having anoptical fiber sensor215 coupled thereto or integral therewith may be utilized is to position thecatheter210 or other workinginstrument240 within theheart230, e.g., to diagnose, treat or ablate endocardial tissue. In the illustrated application, a robotically controlledinstrument200 including a catheter or guideinstrument210 and asheath instrument220 is positioned within theheart230.FIG. 2A depicts delivery of theinstrument200 utilizing a standard atrial approach in which the robotically controlledcatheter210 andsheath220 pass through the inferior vena cava and into the right atrium. An image capture device (not illustrated inFIG. 2), such as an endoscope or intracardiac echo (“ICE”) sonography catheter (not shown inFIG. 1), may be advanced into the right atrium to provide a field of view upon the interatrial septum. Thecatheter210 may be driven to theseptum wall132, and theseptum132 may be crossed using a conventional technique of first puncturing the fossa ovalis location with a sharpened device, such as a needle or wire, passed through a working lumen of the catheter110, then passing a dilator or other workinginstrument240 over the sharpened device and withdrawing the sharpened device to leave thedilator240, over which thecatheter210 may be advanced.
• Various working instruments240 (not shown inFIG. 1) may be delivered through the lumen of thecatheter210 as necessary and depending on the surgical application. For example, for treatment of atrial fibrillation, the workinginstrument240 may be an ablation catheter that delivers targeted radio frequency (RF) energy to selected endocardial tissue. Further aspects of such systems, devices and applications are described in U.S. application Ser. No. 11/176,598, the contents of which were previously incorporated herein by reference.
• Anoptical fiber sensor215 may be used in various applications and may be coupled to or integral with various instruments and surgical system components, and even a patient. For example, in one embodiment, theoptical fiber sensor215 serves as a localization sensor, Which may be used to “localize” or monitor the position and/or orientation of various objects or system components involved in a surgical procedure. Theoptical fiber sensor215 may also be utilized in other applications involving registration, calibration, force calculation and feedback, improved accuracy, mechanical interfacing or “connectorization,” and fiber-based diagnostics. Further aspects of embodiments of the invention and systems in which embodiments may be utilized are described in further detail with reference toFIGS. 3A-49.
• Referring toFIG. 3A, anoptical fiber sensor215 constructed according to one embodiment includes afiber core304 surrounded by acladding306. Thecore304 includes a distributed Bragg reflector, such as one or more Fiber Bragg gratings or FBGs302 (generally referred to as FBGs or gratings302), which are formed within or written into thecore304.FBGs302 can be inscribed or written into thecore304 of afiber215, e.g., in a periodic manner, using various known methods and devices. For example, an ultraviolet (UV) laser may be used to “write” a periodic variation of refractive index (n) into thecore304 of a photosensitive germanium-doped silica fiber. Various types and arrangements ofFBGs302 may also be utilized in embodiments including, for example, uniform, chirped, tilted, superstructure, uniform positive-only, Gaussian-Apodized Index FBGs. For ease of explanation, this specification refers generally to one ormore FBGs302 generally, but it should be understood that different numbers, types and arrangements ofFBGs302 may be utilized in embodiments, and that various system components may includefibers215 so configured.
• FIG. 3A illustrates asingle fiber215 and asingle FBG302 written on or within thecore304. In other embodiments (e.g., as generally illustrated inFIGS. 3B-C), anoptical fiber sensor215 may have afiber core304 that includesmultiple FBGs302 or sets thereof that are axially distributed along thecore304. In certain embodiments, theFBGs302 may be continuous, overlapping or partially overlapping.
• In one embodiment, as illustrated inFIG. 3C, acore304 may include different sets361-362 ofFBGs302 that have different reflectivities. AlthoughFIG. 3C illustratessets361,362 having threeFBGs302 for purposes of illustration, it should be understood that different numbers of gratings may be utilized, and the number ofgratings302 in eachset361,362 may be the same or different. For example, in the illustrated embodiment, the reflectivity of thefirst set361 ofFBGs302 may be configured to have relatively low reflectivity, whereas anotherset362 has slightly higher reflectivity. In one embodiment, afirst fiber215 may include gratings of a first reflectivity, and asecond fiber215 may include gratings of a second, different reflectivity.
• In another embodiment, asingle fiber215 hasFBGs302 of different reflectivities, which may be suitable for use with both optical frequency domain reflectometry (ODFR) and wavelength division multiplexing (WDM) processors that are operably coupled to thesame fiber215. En this manner, embodiments combine the advantages of two different processing systems. OFDR is suited for lowreflectively gratings302 of the same wavelength and is beneficial since it may be able to handle a larger number of gratings per length offiber215 compared to WDM, whereas WDM is suited forhigh reflectivity gratings302 of different wavelengths, and can achieve high signal-to-noise rations. Thus, embodiments may advantageously utilize both OFDR and WDM on thesame fiber215. Further aspects of OFDR and WDM processing are described in U.S. application Ser. No. 12/106,254, the contents of which were previously incorporated herein by reference.
• Thus, various figures, includingFIGS. 3A-C, are provided as examples of howFBGs302 may be arranged, and it should be understood that various numbers and arrangements ofFBGs302 may be utilized, that theFBGs302 may have the same or different reflectivities. Further, whileFIG. 3A illustrates afiber215 having a cylindrical shape,other fiber215 configurations and shapes can be utilized, and the outer surfaces offibers215 may be configured or have structural attributes (shapes or other structural features) to interface with an inner surface or corresponding structural attribute of acatheter210 or other instrument to form a key-like arrangement that limits or prevents twisting or rotational movement of thefiber215 within thecatheter210.
• For example, referring toFIG. 4A, in one embodiment, anoptical fiber sensor215 has an oval-shapedouter surface402. An inner surface of acatheter210 may have a corresponding oval shape to mechanically limit or prevent twisting of thefiber sensor215 within thecatheter210. According to another embodiment, referring toFIG. 4B, afiber sensor215 is configured such that it includes an arcuate or cylindricalouter surface404 and a linear or flat outer surface, segment orbeveled edge406. Although oneflat segment406 is illustrated, afiber sensor215 may include other numbers of segments, which may be arranged symmetrically or asymmetrically. An inner surface of acatheter210 may have a shape corresponding to the surface shown inFIG. 4B to limit or prevent rotation of thefiber sensor215. Referring toFIG. 4C, in a further embodiment, anoptical fiber sensor215 may also comprise multiple fibers, e.g., twofibers215a,215b,which have mating faces406a,406band respectivecylindrical surfaces404a,404bto form a shape that resembles the number 8. AlthoughFIG. 4C illustrates twofibers215a,215b, other numbers offibers215 may be configured to interface with each other with corresponding faces oredges406 or other interfacing surfaces resulting in other shapes. An inner surface of acatheter210 may have a shape corresponding to this outer surface to prevent or limit twisting or rotation of thefibers215a,215b.Referring toFIG. 4D, according to another embodiment, anoptical fiber sensor215 may have an edge406 (as shown inFIG. 4B) and adeeper groove408 formed therein. An inner surface of acatheter210 may have a corresponding segment or protrusion configured to mate with thegroove408 to avoid twisting or rolling between thefiber215 and thecatheter210. Although thegroove408 is shown as having a rectangular shape, other shapes may also be utilized, e.g., V-shaped grooves and other shaped grooves. Further, while embodiments are described with reference to anoptical fiber215 being disposed within an instrument such as acatheter210, embodiments may also he applied to a fiber that is coupled to an outer surface of an instrument.
• Additionally, eachfiber215 may contain a single core or comprise multiple sub-cores. In a further embodiment, referring toFIG. 4E, theoptical fiber sensor215 may include an “off-center”single core304, which may he beneficial since the shape of thefiber215 having onecore304 can be calculated under constrained conditions knowing the roll orientation axial strain on thecatheter210.
• Further, while figures illustratecertain core304 andFBG302 configurations and arrangements, embodiments may utilize a singleoptical fiber215 having oneFBG302, a singleoptical fiber215 including amultiple FBGs302 distributed along thecore304,multiple fibers215, each of Which includes oneFBG302,multiple fibers215, each of which includesmultiple FBGs302 distributed alongrespective cores304, ormultiple fibers215, some of Which have only oneFBG302, and others that includemultiple FBGs302, and the FBGs may have the same or different reflectivities.
• Certain fibers215 may also be different sizes. According to one embodiment, the diameter of afiber215 configured for insertion into a patient is smaller than the diameter of afiber215 that is utilized externally of the patient. For example, the diameter of afiber215 intended for insertion into a patient may have a diameter of about 150 microns, and a diameter of afiber215 intended for use outside of the patient may have a diameter of about 200 microns or greater, e.g. about 500 microns.
• Embodiments utilizing afiber core304 having a distribution of axially-spacedBragg gratings302, which may, for example, be continuous or substantiallycontinuous FBGs302 written on the at least onefiber core304, provide for various control options. In one embodiment, acontroller340 of the output unit orreadout system300, or a controller or computer of the robotic surgical system, or combination thereof, is configured to sample therespective FBGs302 while selectedgratings302 are sampled more frequently than others. For example,gratings302 that are sampled more frequently may be located on a portion of the Bragg sensor optical fiber325 coupled to a distal end portion of theinstrument210. Further, thecontroller340 can be configured to actively change which Bragg gratings302 are selected for more frequent sampling based upon, for example, movement of theinstrument210. In yet another embodiment, thecontroller340 may be configured to identify a most proximal Bragg grating302 that is selected for more frequent sampling based on a detected increase in signal amplitude from therespective grating302 as compared to moreproximal gratings302.
• Additionally, embodiments may involveinstruments210 having multipleoptical fiber sensors215, each of which hascores304 having axially-spaced Bragg gratings302. Thecontroller340 may be configured to samplerespective sensor gratings302 on thefiber cores304, and to conduct common mode error analysis by comparing signals received from respectivecorresponding gratings302 thereon. As an example of common mode analysis, first and second Bragg sensoroptical fibers215 may be attached to the sameelongate instrument210 in an identical manner except that thefibers215 may be attached at different locations. For example, the first andsecond fibers215 may be attached diametrically opposite each other of anelongate instrument210 that has the shape of a cylinder. In this example, through analysis of the signals236 reflected from eachfiber215, the location of the tip of the cylinder can be determined. The signals236 from bothfibers215 can be averaged together taking into account that thefibers215 are a known distance away from each other, and noise in the measurement can thus be reduced in this manner.
• Referring again toFIG. 3A, in the illustrated system configuration, light emitted322 by alight source320, such a laser, is directed into thefiber core304 through one or more suitable interfaces, couplers or connectors (generally illustrated as328), and transmitted through thefiber core304 to one ormore FBGs302.Light322 may be partially transmitted324 through the one ormore FBGs302, and partially reflected326.Reflected light326 propagates in the opposite direction through thecore304, through one or more suitable interfaces, couplers orconnectors328, and is detected by adetector330 of an output or read out unit (generally identified as300). Theconnectors328 are configured to serve as interfaces between one ormore fibers215 and one or more output or read outunits300.
• As shown inFIG. 3A, acontrol element340 is located in theoutput unit300. In another embodiment, acontroller340 is located in controller or computer of a robotic surgical system (e.g. as shown inFIGS. 22A-C). Theoutput unit300 may also be integrated within or a part of a controller or computer of a robotic surgical system. In a further embodiment, acontroller340 includes components of theoutput unit300 and another computer or controller of a robotic surgical system that are operably coupled together. For ease of explanation, reference is made generally to acontroller340, but it should be understood that the controller may be a standalone component or multiple components that are operably coupled together.
• In certain embodiments, thecontroller340 is configured for applications involving shape, position and/or orientation of robotic surgical system components, calibration, therapeutic, diagnostic and localization procedures. The controller be implemented as hardware, software or a combination thereof, and may be processor, a micro-controller, or a computer, which is part of, or associated with, the read outunit300 or a robotic surgical system. The controller may process reflected light326 and issue controls in response thereto, e.g., to adjust the shape or reposition of an instrument of a robotic surgical system (as generally illustrated inFIG. 3A), or generate representations of system components on a display.
• It should be understood that the system configuration illustrated inFIG. 3A is provided to generally illustrate system components and how they may be generally configured, and that other components and configurations may be utilized. For example, althoughFIG. 3A illustrates asingle fiber sensor215,multiple fiber sensors215 may also be utilized together with additional system components as necessary. Further, eachfiber sensor215 may have a dedicated detector oroutput unit330 orfibers215 may share a detector oroutput unit330. Further, althoughFIG. 3A illustrates a separatelight source320 and output or read outunit300, thelight source320 may also be a part of the output unit300 (represented by dotted line). Other system configurations and/or components may be utilized, examples of which are described in further detail in U.S. patent application Ser. Nos. 11/678,001, 11/678,016 and 11/690,116 and U.S. Provisional Application Nos. 60/785,001 and 60/788,176, the contents of which were previously incorporated by reference. Accordingly,FIG. 3A is provided to generally illustrate system components and how they may be implemented in a robotic surgical system, but other numbers and configurations and components ay be utilized as necessary.
• FIG. 5 illustrates one example of a situation that embodiments anoptical fiber sensor215 and related systems and methods are capable of addressing or preventing. As shown inFIG. 5, a mismatch between a shape of arepresentation12 of acatheter210, which may be generated using a kinematics model, and a shape of animage14 of thecatheter210, which may be generated using fluoroscopy, is displayed10. Embodiments of anoptical fiber sensor215 are coupled to or integral with acatheter120 and address or prevent these types of mismatches by providingaccurate catheter210 shape data, thereby allowing for accurate manipulation and positioning of thedistal portion211 of thecatheter210. Embodiments may also be utilized to provide accurate position data.
• For example, referring toFIG. 6, according to one embodiment, anoptical fiber sensor215 including one ormore FBGs302 as described previously is coupled to or integral with acatheter210 and used as a localization sensing device to determine and display position of a given point upon aninstrument210 on adisplay350. In the illustrated embodiment, a two-dimensional image14 is generated using fluoroscopy and displayed350. Theimage14 may be shown independently (as shown inFIG. 6), or together with other representations and/or images. In one embodiment, theimage14 is displayed together with thevirtual catheter representation12 or “cartoon object” that is generated according to a kinematics model (as described with reference toFIG. 1).
• As shown inFIG. 6, embodiments are used as a localization sensing device to generate three-dimensional position data or spatial coordinates (x-y-z)602 of a given point on thecatheter210. In this manner, theimage14 is presented with more accurate x-y data, and z data is also generated such that a location of thecatheter210 ordistal portion211 thereof can be accurately determined or extracted from theoptical fiber sensor215 data. In this manner, a user or surgeon can know precisely where thedistal portion211 or tip of thecatheter210 relative to surrounding tissue.
• Referring toFIG. 7, in another embodiment, in addition to the accurate x-y-z data602 (as described with reference toFIG. 6), orientation, roll or “twist” angle data (α, β)702 may also be determined or extracted from theoptical fiber sensor215. In this manner, embodiments may be used to provide position (x, y, z)602 and orientation (α, β)data702, which may be particularly beneficial when the distal tip of theinstrument210 is at or adjacent to a target area or tissue.
• Thus, referring toFIG. 8, one embodiment is directed to amethod800 of generating and displaying a representation of aninstrument body210 and includes positioning theinstrument body210 within the patient atstage805, and directing light322 through anoptical fiber sensor215 attached thereto or integral therewith atstage810. Atstage815, light326 is reflected by, e.g., aFBG302, that is formed within acore304 of theoptical fiber sensor215. Atstage820, reflected light326 is sensed or detected by adetector330, which may, for example, be a part of or operably coupled to a controller oroutput unit300. Atstage825, acontroller340 or other suitable control element operably coupled to thedetector330 or read outunit800 is configured to process data associated with the reflected light326 to generate data such as spatial position and/or orientation data. Atstage830, animage14 and/orother representation12 of theinstrument body210 is generated and displayed350. The shape and/or position of theinstrument210 is accurately depicted in, for example, animage14, based on data determined or derived from the light reflected326 byFBGs302 of theoptical fiber sensor215. Embodiments may also be utilized for other methods and may involve generating of animage14 and anotherrepresentation12.
• Given the number of points along a giveninstrument210 that may be sensed with aBragg grating fiber215, embodiments advantageously allow for accurate sensing of the shape and/or position of theinstrument210. Shape recognition algorithms, which may be configured to detect the position of radioopaque markers positioned upon theelongate instrument210, for example, may also be utilized to detect the position of theinstrument210 in space automatically. in the event of a mismatch between theBragg grating fiber215 basedcartoon object12 and the fluoroscopic images14 (e.g., depending on the accuracy of theBragg gating fiber215 positioned along theelongate instrument210 and the accuracy of shape recognition, or marker recognition algorithms), a procedure may be interpreted. For example, a robotic drive motor may be deactivated automatically, or subsequent to a notification (audible, visual, etc.) to the operator that a mismatch exists.
• The position and/or orientation of other components may also be displayed, and they may be displayed350 together with arepresentation12 generated according to a kinematic model (as discussed above) and/or with other representations or images, e.g., together with an indicator of an orientation of an image capture device, such as an actual or virtual camera, ultrasound image capture device, optical or infrared imaging chip, etc. In the illustrated embodiment, the orientation of an image capture device is represented as anarrow object710. Thearrow object710 indicates the origin position and vector of the orientation of the image capture device relative to other objects presented upon the same display in two or three dimensions. In other embodiments, the display element depicting roll can be a display of roll angle, or another arrow, a horizon indicator, etc. Thus, it should be understood that additional “cartoon” objects or representations showing the position and/or orientation of different types of system components can be displayed together with the representation510 of aninstrument210 based upon localization information.
• Further, other localization sensors can be used to determine the shape, position and/or orientation of one or more points of an elongate instrument, such as acatheter210, in space—and such points may be utilized to construct and display a cartoon or representation ofsuch instrument210 relative to other images of the same object, generated based upon fluoroscopy, other models, etc. For example, other localization sensors may be coupled to an instrument body such as acatheter210 and/or coupled to afiber215. Thus, acatheter210 may include an attachedfiber215 and localization sensor, or the localization sensor may be coupled to thefiber215 instead. Suitable localization sensors that may be used for this purpose include, for example, electromagnetic coils (such. as those available from Biosense Webster or Ascension Technology), potential difference sensing devices (such as those available from St. Jude Medical), and ultrasound sensors. Further aspects of such devices are described in further detail in U.S. application Ser. No. 11/637,951, the contents of which were previously incorporated reference.
• Thus, embodiments ofoptical fiber sensors215 can be used to “localize” or monitor the positions and/or orientations of various objects or system components involved in a particular procedure. For example, not only is it useful to localize instruments, e.g., acatheter210, configured and utilized for endocorporeal use in a given procedure, but also it is useful to localize other associated objects and components, such as structures utilized to present theoperational instruments210 into the body, structures utilized to stabilize the body, the body itself or portions thereof. Further, depending upon the capabilities (for example bus and processing capabilities; certain localization systems are only capable of sensing a small number of sensors in parallel;Bragg Grating sensors215, on the other hand, may be utilized to gather at least positional information regarding many points along a given structure or multiple structures, depending upon the particular signal processing configuration) of the localization system utilized, multiple mechanically-associated objects may be localized simultaneously. For example, theinstrument200 shown inFIG. 2A includes three coaxially associated instruments--anouter sheath catheter220, an inner coaxially-associatedcatheter210 such as a guide catheter, and a workinginstrument240 such as a guidewire, a pusher wire, an ablation catheter, a laser ablation fiber, a grasper, a collapsible basket tool, etc., which is positioned within the working lumen defined by theinner catheter210, and all of which may be localized simultaneously with embodiments for maximum operator feedback and system control.
• An instrument or component of a robotic surgical system having anoptical fiber sensor215 can also be used in other methods, and with external structures, such as instrument driver structures, proximal instrument block structures, instrument driver setup structures, fluoroscopy gun and/or arm structures, etc. With embodiments, these other system components may also be localized and monitored.
• Optical fiber sensors215 can also be coupled or attached to a patient, e.g., to a patient's chest. With this configuration, the position of the patient's chest may be localized to provide the system and operator with the ability to understand changes in position and, for example, gate or pause activities during deep breaths or body movements, simply warn the operator with visual, audible, and/or haptic feedback, or facilitate recalibration of relative positioning between instruments and the patient, for example. Such techniques may be utilized to present an operator with pertinent information regarding the position and/or orientation of one or multiple instruments.
• For example, it may be useful to present such information for two or more robotic arms or robotic catheters being utilized in a given operational theatre. Further, it may be useful to present such information for one or more imaging device, such as an ultrasound catheter. Further, such techniques are highly useful in not only electromechanically-driven instrument scenarios, such as with robotic arms or robotic catheters, but also in manually-actuated instrument scenarios, where handles and other components are utilized to operate instruments.
• Referring toFIG. 9, another embodiment is directed to amethod900 of controlling an instrument or elongate body, such as thecatheter210, based on the shape and/or orientation of thecatheter210 that is expected versus the shape and/or orientation actually achieved or measured using anoptical fiber sensor215. Themethod900 includes receiving a user command associated with a new or desired location of thecatheter210 atstage905, and allowing thecatheter210 to move atstage910 according to the command issued or received atstage905. Atstage915, a determination is made whether the measured location of thecatheter210 changed as expected based on the shape and location information received from theoptical fiber sensor215 coupled thereto or integrated therein atstage920. If so, then atstage925, a further determination is made whether thecatheter210 has reached or is positioned at the commanded or final destination, position or orientation. If so, the method is successful and complete atstage930. Otherwise. thecatheter210 can be moved further atstage915 and method steps can be repeated as necessary until the final destination has been reached. However, movement of thecatheter210 may also result instage920 resulting in a determination that the measured location changed in an unexpected way, in which case a warning may be issued and/orcatheter210 movement can be limited or aborted atstage935.
• Referring toFIG. 10, other embodiments are directed to amethod1000 of generating a structural map of an internal body tissue, such as endocardial tissue. The method includes maneuvering adistal end portion211 of an elongate flexible instrument orcatheter210, which includes anoptical fiber sensor215, within an anatomical workspace in a body atstage1005, and detecting When adistal end211 of theinstrument210 contacts a tissue surface in the workspace atstage1010. Atstage1015, a geometric configuration of thedistal end portion211 of theinstrument210 is determined when thedistal end211 contacts the tissue surface, e.g., based on light reflected226 by one ormore FBGs302. Atstage1020, position data is generated and indicative of a position of the instrumentdistal end portion211 based upon the determined geometric configuration of the instrumentdistal end portion211 when thedistal end portion211 of theinstrument210 contacts the tissue surface. Atstage1025, one or more or all of the previous stages can be repeated as necessary in order to generate sufficient position data to generate a structural map of the tissue surface.
• Referring toFIG. 11, in another embodiment, multiple robotically controlledcatheter instruments210a,bmay have respectiveoptical fiber sensors215a,bcoupled thereto (e.g., extending through alumen213 or217). In the illustrated embodiment, one roboticallycontrollable catheter210ahas anoptical fiber sensor215acoupled thereto and carries or supports an imaging device orimaging catheter1102. Another roboticallycontrollable catheter210bincludes anoptical fiber sensor215band carries or supports amapping catheter1104, which is used to map electrical signals within theheart330, With this configuration, embodiments advantageously allow the shape and location ofmultiple catheters210a,bthat are used for different purposes to be determined by use of light reflected byFBGs302 of respectiveoptical fiber sensors215a,b.
• Yet other embodiments are directed to methods involving system components other than elongate instruments or catheters. For example, referring toFIG. 12, other systems and associated methods may involve determining one or more position and/or orientation variables of aninstrument driver1200 that includes one ormore motors1205 that can be actuated to controllably manipulate a bendabledistal end portion211 of an elongate instrument or catheter210 (which may also have anoptical fiber sensor215 coupled thereto as illustrated) based on detected reflectedlight signals326 received from therespective FBGs302 on theoptical fibers215.FIG. 12 generally illustrates an output or readout unit/controller300/340 for ease of illustration, but may include components such as a light source, detector, etc., as discussed with reference toFIG. 3A andFIGS. 22A-C.
• Referring toFIG. 13, in a further embodiment,optical fiber sensors215a,bare coupled to respective robotically controlledcatheter instruments210a,b, which may carry or support other devices or catheters such as an imaging device orimaging catheter1102 and mapping catheter as discussed with reference toFIG. 11. Additionally, in the illustrated embodiment, additionaloptical fiber sensors215c,dare coupled to controllers, anus orinstrument drivers1200a,bthat are used to control or manipulate therespective catheters210a,b. The arms, instrument drivers orcontrollers1200a,bare typically located outside of the patient's body and, in one embodiment, thefiber sensors215 are larger than thefiber sensors215 that are coupled to catheters orelongate instruments210a,band advanced into the patient's body. For example,fibers215c,dthat are located outside of a patient can have a diameter of greater than 200 microns, e.g. about 500 microns, whereasfibers215a,bfor use within a patient may have a diameter of about 150 microns. With this configuration,larger diameter fibers215c,d. can then have the individual cores spread further apart which, may be utilized to increase the accuracy of the measurements by increasing the difference in signal produced by cross-sectionally opposing fibers. Thelarger diameter fibers215c,dcan accurately measure the location of the arm ordriver1200a,b, and thesmaller diameter fibers215a,bcan measure from a point where thelarger diameter fiber215c,dends.
• In another embodiment, referring toFIG. 14, other systems and associated methods are directed to determining one or more position and/or orientation variables of animage capture device1400 based on light reflected226 byBragg gratings302 on a Bragg sensoroptical fibers215bcoupled to or integral with theimage capture device1400. Examples ofimage capture devices1400 include a fluoroscope, an optical camera, an infrared camera, an ultrasound imager, a magnetic resonance imager, and a computer tomography imager. In the illustrated embodiment, thecatheter210 and theimage capture device1400 are advanced through anouter sheath220 and include respectiveoptical fiber sensors215a,b, but other system configurations may be utilized. Acontroller340 may be configured to determine one or more position and/or orientation variables of theimage capture device1400 based onsignals326 received fromBragg gratings302 on afiber215.
• Referring toFIG. 15, other methods and systems are directed to anoptical fiber sensor215 that is attached to a patient'sbody1500, e.g. thechest1505 of apatient1500, using a patch or other suitable adhesive. For example, afiber sensor215 may be coupled to the patch that is applied to a patient1502. Such embodiments are useful for determining one or more position and/or orientation variables of the patient'sbody1500 to which anoptical fiber sensor215 is attached based on signals reflected226 by one or more Bragg gratings302.
• This configuration allows for detection of an unexpected movement of apatient1500 based on signals received from therespective FBGs302, in response to which an output can be generated for the system operator to allow the system operator to adjust thecatheter210 within thepatient1500 as necessary, temporarily suspend the procedure, or halt the procedure. Further, such embodiments area also useful for generating an image of thepatient1500 or such that an image of apatients body1500 that is displayed can be moved or adjusted according to the movement sensed using theoptical fiber sensor215. Other methods may involve coordinating diagnostic and/or therapeutic procedures on the patient with the patient's respiration as determined by light reflected226 by one ormore FBGs302.
• More particularly, as described above, it is desirable to know where thepatient1500 and the anatomy are located in relation to the catheters orelongate instruments210. For example, if thepatient1500 unexpectedly moves, a warning may be generated to reposition thecatheter210 or other components. Thus an automatic, semi-automatic or a manual feedback loop may be created based on the position of thepatient1500. Embodiments provide for using a shape andlocation measurement fiber215 forpatient1500 monitoring. A key advantage of embodiments is that a single technology (in this example a Bragg-grating fiber215) may be used for locating all the essential components of the environment, although other localization technologies, such as electromagnetic and potential-difference based localization technologies, may also be used, depending upon the capabilities of the particular system employed.
• When navigating, or “driving”, in static image-based (preoperative or intraoperative) models, such as those created utilizing modalities such as MRI and/or CT, it is advantageous to register the model to thedistal tip211 of theelongate instrument210; after such registration has been accomplished, if thepatient1500 moves, the registration relationship may be significantly altered, requiring another registration unless embodiments as illustrated inFIG. 15 are utilized. With embodiments, a patient localization device which in one embodiment is anoptical fiber sensor215 is used to understand the relative geometric/spatial relationships of theinstrument210 components and patient1500 in real, or near-real, time, in which scenario registration may be updated manually or automatically.
• There are several ways to attach theoptical fiber sensor215 to thehuman body1500. One method involves wrappingfiber sensor215 around thechest1505 of thepatient1500. As discussed above, another technique is to attach thefiber sensor215 to a patient patch, and applying the patient patch to thechest1505 of thepatient1500. As thefiber sensors215 are very thin, the images of thefibers215 viewed via animage capture device1400 such as a fluoroscope generally are not objectionable. Further, thefiber sensor215 may be attached to a radio-opaque marker (net illustrated inFIG. 15) such that it is possible to see the markers and associatedfiber sensor215 clearly in a fluoroscopic image. As the exact location of the marker can also be determined by the location measurement system of thefiber sensor215, the location of the marker can thus be known in two coordinate systems—the coordinate system of thefluoroscopic imaging system1400 and the coordinate system of the shape and locationmeasurement fiber sensor215. This permits a way to spatially associate the coordinate system of thefiber sensor215 with the coordinate system of theimaging system1400.
• More particularly, in one embodiment, referring again toFIG. 14, a shape andlocation measurement fiber215 is coupled to anexternal imaging device1400 such as a fluoroscope. The knowledge of the location of thefluoroscope1400 is advantageous for the combination display of the fluoroscopic image and the virtual catheters and for aligning the coordinate systems of theimaging system1400, thefiber sensor215 based device and the robot orother control mechanism1200. This is particularly true in the embodiment wherein one has a fluoroscopy display driving to be instructive to the operator.
• Patient1500 respiration may also he monitored with thefiber215 based measurement system. As the patient'schest1505 moves with breathing, theoptical fiber sensor215 attached. thereto also moves. These movements can be monitored, and this information can then be fed back into the robotic navigation system and may be used, for example, to accurately deliver therapy. Elaborating on this example, in the situation in which thecatheter210 holds or supports an ablation catheter, ablation energy can be delivered at the same point in the respiratory cycle or the respiratory and cardiac cycle. This may improve the accuracy and effectiveness of ablations.
• Monitoring patient1500 respiration and. movement can lead to yet another advantage. In many electrophysiology procedures, models of the inside of theheart230 are built by various methods. These models are quite distinct from images as a model is a parametric representation of theheart230. These models are often stationary in that they do not contain any information about the dynamics of theheart230 or the dynamics of thepatient1500 such as due to respiration. These models are used for navigation purposes for example to navigate acatheter210 inside of theheart320. The availability ofpatient1500 movement data such as via respiration) though the use of afiber sensor215 or other localization technique, advantageously enables compensation or adjustment of the model.
• Embodiments can also be utilized for purposes of registration, or for spatial association of Objects and/or images. Such registration may be continuous or semi-continuous, based on a common reference or connected by a defined relationship. References may also be connected by a defined relationship or associated utilizing other imaging modalities.
• As discussed above, in known minimally invasive procedures, anelongate instrument120 may be inserted within the body and an imaging device such as a fluoroscopic system may be utilized to image, or “visualize”, theelongate instrument120 or a portion thereof, but a drawback of known fluoroscopic imaging systems is that they are projection based—the depth information is lost and therefore true three-dimensional location of objects such as an elongate instrument in the field of view of the fluoroscope is lost. However, with embodiments, anelongate instrument210 has a shape and location measuring fiber oroptical fiber sensor215 that provides the three-dimensional location of specific locations in a continuous or semi-continuous manner, thus allowing for automatic registration. Locations of interest may be visualized with the fluoroscope and spatially analyzed utilizing techniques such as pattern, geometry, shape, movement, and/or marker recognition (preferably with the help of radioopaque markers positioned upon portions of the subject instrument, beacon transducers placed upon the instrument for ultrasound pinging localization, or other techniques to localize with fluoroscopy); such results then may be processed in conjunction with the location information obtained about these same locations from thefiber sensor215 based measurement device. Image information from the two techniques may be utilized to make the images produced by each appropriately and accurately associated with the other in three-dimensional space.
• A Bragg gratingfiber sensor215 based shape and localization measuring device may be attached to one or more or all of the key elements in an operating room environment including, for example, acatheter210 or other elongate instrument, to controllers orinstrument drivers1200 that control the location of thecatheter210, to the bed supporting thepatient1500, to thepatient1500, and to animage capture device1400 such as an external imaging system, one example of which is a fluoroscopic system. it is advantageous if all of thefiber sensors215 in this embodiment have a single common reference point or reference coordinate system, preferably located as distally as possible without compromising the mechanical behavior of the system (to increase the effectiveness of common-mode error rejection analysis, which may be applied, to light or data moving through the system of localization fibers215). This ensures that the coordinate system for the devices and instruments and objects to which thefiber215 based system is coupled are all similarly and precisely spatially associated during registration.
• Eachfiber215 may have its own reference point, and each reference point may refer to a single coordinate system for coordination. Different instruments may each have afiber215, and in this case, and the relationship between different instruments can be determined based on a fixed spatial relationship between instruments, or if there is not a fixed spatial relationship, then each fiber on each instrument may refer to the same coordinate system, and data from the fibers can be used for an necessary adjustments. Thus, with embodiments, the position and/or orientation variables of a plurality of elongate instruments, each of which includes an elongate instrument body having a Bragg sensoroptical fiber215 coupled thereto, may be determined and registered in a single reference coordinate system. The instrument bodies may be coupled to a same or different structure in a known spatial relationship, or coupled to a same or different structure in an unknown spatial relationship. In the latter case, registration of the instrument position and/or orientation variables of respective instruments in a single reference coordinate system is accomplished by maintaining a fixed distance between respective locations on the instrument bodies.
• Even if the references for all of thefiber sensors215 are not the same, in one embodiment there is a defined relationship between the different references such that the relationship between the different coordinate systems is accurately defined and may be utilized to analyze the spatial relationships between coordinate systems. For example, two references may be utilized for twofibers215 attached to two devices, with the two references connected by a stiff structural rod or member (or another device that prevents relative movement between the reference points, or with other devices to predictably understand the geometric/spatial relationship between the two references) to prevent relative motion between the references.
• Other technologies such as an electromagnetic or potential-difference-based localization, lasers or ultrasound (for beaconing, shape/marker/pattern/etc. recognition, and/or time-of-flight analysis to determine relative spatial positioning) may be used to establish the absolute positions of each reference. For example, an electromagnetic localization sensor may be placed on eachBragg fiber215 to obtain the three-dimensional coordinates relative to a coordinate system established by the electromagnetic localization system. The measurements provided by eachfiber215 all are consistent with each other as they all are referenced back to a common reference.
• Embodiments may also be utilized in procedures for calibration instruments and tools in which the instrument or tool includes anoptical fiber sensor215. While certain techniques for calibration are known, embodiments provide apparatus and methods for calibrating a robotically controlled elongate instrument attached to one or more shape andlocation measuring fibers215.
• Initial calibration information can be Obtained utilizing several techniques. In one method, measurement or observation of properties and/or behaviors of the instrument having anoptical fiber sensor215 and being calibrated are observed. Other methods involve obtaining information from the design of the localization/shape-sensingfiber215, theelongate instrument210, or both. Yet other methods involve use of calibration or test fixtures adapted for an instrument that includes anoptical fiber sensor215.
• Referring toFIG. 16, acalibration procedure1600 according to one embodiment includes positioning an instrument or tool in a known geometric configuration atstage1605. Atstage1610, a sensed geometric configuration is determined based on signals or light326 received from the one ormore Bragg gratings302 of afiber sensor215 while theinstrument body210 is in the known geometric configuration. Atstage1615, the sensed geometric configuration is compared with the known geometric configuration. Atstage1620, if necessary, data representative of the comparison is stored on a storage medium associated withinstrument210. The storage medium may be, for example, a programmable device, a bar code, a “RED” device, or a memory dongle, which may be positioned within or coupled to theelongate instrument210, a software of a system component associated with theelongate instrument210, or an external device such as an external server, in which case retrieval can be performed via a computer network. Thus, in one embodiment, calibration of aninstrument210 that has an opticalfiber position sensor215 includes performing a predetermined task with theinstrument210, acquiring measurements or recording relevant information, storing such information or derived information, and retrieving such information for use in normal operation.
• Referring toFIG. 17, a diagnostic or therapeutic procedure11700 may be performed using the instrument calibrated as shown inFIG. 16. Atstage1705, the instrument so calibrated is maneuvered within a patient's body. Atstage1710, one or more sensed position and/or orientation variables of the instrument are determined based on signals received from the one ormore FBGs302 while the instrument is in the patient's body. Atstage1715, the sensed position and/or orientation variables are adjusted based on calibration data, which may be stored in a storage medium.
• The types of information that can be stored (for example, upon a memory chip associated with or coupled to the elongate instrument) as part of calibration include but are not limited to, a diameter of afiber215 orfiber core304, a position of acore304 within afiber215, a position offibers215 within or coupled to anelongate instrument210 or other system component, a position of eachFBG302 formed within thecore304, a reflectivity of eachFBG302, thermal characteristics of thefiber215, mechanical properties of thefiber215 including stiffness, offsets and gain, and mechanical properties of the combination of thecatheter210 andfiber215 coupled thereto, such as stiffness and position or orientation dependent properties. Calibration information can be stored in various places and devices including but not limited to, a programmable device within or coupled to theelongate instrument210, software of a system component associated with theelongate instrument210, an external device such as an external server in which case retrieval can be via a computer network, a bar code, a “RFID” device, or a memory dongle.
• Initial calibration information for use in embodiments can be obtained utilizing several methods. In one embodiment, calibration of anelongate instrument210 that includes an opticalfiber position sensor215 coupled to a distal portion or tip211 thereof involves driving theelongate instrument210 to a known position in a well-defined and characterized geometric fixture or test structure. The operator then compares the reading from thesensor215 to the known position. The reading can thus be equated to the known position.
• FIG. 18 illustrates one embodiment of atest fixture1800 and associated method that may be used during calibration procedures in the illustrated embodiment, thetest fixture1800 is made from a rigid material such as glass, plastic or another material in which acalibration groove1802 can be formed. In the illustrated embodiment, thegroove1802 spans a quarter of a circle or has a bend of about 90 degrees. Thegroove1802 is configured to accommodate acatheter210 and anoptical fiber sensor215 coupled thereto or integral therewith to ensure that the combination of thecatheter210 andoptical fiber sensor215 can both bend with thegroove1802, e.g., at about 90 degrees. The measurements from thefiber215 may be read for this section and any error may be calibrated out,
• In another embodiment, therigid structure1800 may define a linear or straight groove rather than agroove1802 at about a 90 degree bend as illustrated inFIG. 18. With this configuration, similar to the embodiment described above, the linear groove is configured to accommodate thecatheter210 and theoptical fiber sensor215. During use, the combination of thecatheter210 andfiber sensor215 is positioned within the linear groove, and readings from eachFBG302 are obtained using a detector orfiber readout unit330. This establishes a “zero” reading for the combination of thecatheter210 and theoptical fiber sensor215 and corresponds to a linear or straight shape. Any other shape will be measured relative to a zero shape.
• However, a zero shape does not have to be a straight shape. A zero shape could be any predefined arbitrary shape. A non-straight zero shape may be desirable if, for example, a fiber is integrated to a pre-bent catheter210 (i.e., the natural shape or the “home” shape of the catheter is not straight but bent).
• Thus, a calibration process may involve placing thecatheter210 and localization/shape-sensingfiber215 in a well-definedrigid structure1800 with a groove, sending light322 Or other appropriate energy) through thefiber215, detecting light226 reflected by one or more FBGs302 within thefiber core304, obtaining strain values and calculating shape, storing the strain values or some derived values in a storage device identifying this as a “zero” shape.
• Calibration procedures and related data can be based on each individual device or a group of devices. For example, if it is known that a certain group ofelongate instruments210 orfibers215 has a certain type of property that effected the measurements in certain ways, this information can become part of the calibration information. From group to group, this information may be different. When thecatheter210 is installed, the system can read the serial number of thecatheter210 or some other form of identification and the correct calibration values can be utilized.
• Embodiments may also be utilized in force calculation and feedback applications. Various techniques may be utilized to calculate force at the distal tip of thecatheter210 or other instrument. One such method is described in U.S. patent application Ser. No. 11/678,016, “Method of Sensing Forces on a Working Instrument”, filed Feb. 22, 2007, previously incorporated by reference herein. A force applied upon an instrument may be calculated by understanding the shape of the instrument with a load applied and utilizing kinematic relationships of the instrument to back out the presumed load applied to the instrument. The calculated load may then be utilized for force feedback to the operator techniques, such as haptics, on-screen displays, warnings to the operator, etc. For example, in one embodiment, if the force exceeds a certain value, then a warning message may he displayed or other actions may be taken to prevent patient injury; yet another alternative to this scheme is that the level when warnings or other actions are initiated may he anatomy specific; for example, in the ventricles where the walls are thicker, higher forces may be applied without triggering an alarm or response.
• As described in the incorporated references regarding fiber-based Bragg diffraction localization, the location measurement at the tip of thelocation measurement fiber215 depends on component measurements obtained from each grating302. In practice, each grating302 will contribute a finite amount of error in measurement. The error at the tip is the sum of all errors, i.e., errors are cumulative. It is thus advantageous to maintain length from the tip to the origin, or the reference, or from where the measurement must be taken, as small as possible. However, thecores304 of theoptical fibers215 may havenumerous gratings302, and the number ofgratings302 may be more than what is required between the tip and the origin. Thus, in one embodiment, it is not necessary to include all of thegratings302 for location measurements at the tip.
• Referring toFIG. 19, in one embodiment, a data acquisition and analysis software, which may, for example, reside in a controller or associated memory of a computer, MID controller, electronics rack or other suitable controller of a robotic instrument system illustrated inFIGS. 22A-C), is configured to pass over, disregard or ignore the first number N gratings1902, thereby placing the reference1904 at the location of the N+1^thgrating302. In the illustrated embodiment, the first twoFBGs302 are ignored, thereby placing the reference1904 at thethird FBG302, which is also at the beginning or proximal end ofcatheter210. This method will provide shapes and location measurements relative to the location of the reference grating.
• In other embodiments, systems and methods are directed to using software executed by acontroller340 to select areference FBG302, ameasurement FBG302 and/or a length or window of aFBG302 to be measured or analyzed. For example, in one embodiment, the location of areference FBG302 is fixed at a proximal end of acatheter210 as described above, and the location where the measurement is to be performed, or themeasurement FBG302 to be selected, is flexibly controlled via software such that the selectedmeasurement FBG302 may change during the analysis. Further, whicheverFBG302 is selected at a given time for measurement, thecontroller340 software can also be executed to select the length of a selected measurement FBG over which the measurement is to be performed. In this regard, the length or window can be the entire length of a selectedmeasurement FBG302, or the length or window may be a portion or segment thereof. For example, about half of ameasurement FBG302 may he selected. for measurement rather than theentire FBG302. Embodiments may be implemented using continuous, overlapping or partially overlappinggratings302.
• If absolute location of the tip is needed, and if the first N FBGs1902 sensors are ignored as shown inFIG. 19, then another independent method can be used to obtain the absolute or relative position of the reference1904. This independent method may be anotherfiber215 which has it tip at the location of the N+1^thFBG302 on thefirst fiber215 is, or it may be an EM based sensor attached on the location of the N+1^thFBG302 or some other device. In all of these cases, the absolute location of the N+1^thFBG302 is measured or its relative location with another absolute reference is measured.
• Various systems and components may be utilized to implement embodiments, and selection of aFBG302 as a reference grating or a measurement may be performed using hardware, software or a combination thereof. Examples of systems and. components thereof that may be used with or to implement embodiments are described in further detail in U.S. Provisional Application Nos. 60/925,449 and 60/925,472, filed on Apr. 20, 2007, and U.S. application Ser. No. 12/106,254, filed on Apr. 18, 2008, the contents of which were previously incorporated herein by reference.
• Two fibers may be used for measuring twist, e.g. as described in U.S. Patent Application No. 60/925,449, “Optical Fiber Shape Sensing System”, filed Apr. 20, 2007, previously incorporated herein by reference. Two ormore fibers215, each of which has a single core or multiple cores, may also be used to improve location accuracy. If the geometric or spatial relationship between thefibers215 is known and invariant, then the independent location measurements from eachfiber215 can be averaged together resulting in improved signal to noise ratio and thereby result in improved accuracy. This technique of improving accuracy works if the noise in each measurement is independent of the noise in the other measurements. However, for any measurement system such as the fiber based measurement system, independent noise will exist. Invariance in the location of the twofibers215 may be obtained through suitable design.
• In many minimally invasive interventional systems, such as those made by Hansen Medical, Mountain View, Calif., there exists a disposable component (for example, a catheter) Which typically enters a human body, and a non-disposable piece, which may, for example, house the mechanisms to control the disposable component. It may be through these controls that navigation of the disposable component is achieved within the body. As described above, according to one embodiment, theinstrument210 or may be coupled to a shape andlocation measuring fiber215. Consequently, the connector(s) between the disposable and non-disposable components are configured to accommodate thecatheter210 and thefiber215.
• Embodiments address mechanical aspects associated with use of anoptical fiber sensor215 in robotic surgical components including at the coupling point or interface prior to thefiber215 exiting the instrument and allows for movement of afiber215 within the instrument. This is achieved by providing slack at the proximal end since the distal end is typically positioned within the body, and thefiber215 would probably be constrained in some fashion at the distal end. In this manner, embodiments address connection issues involving the catheter orelongate instrument210 flexing or bending by providing slack to thefiber215 to prevent breaking or excessive straining of thefiber215. Such slack or “service loop” can be introduced in various ways.
• For example, referring toFIG. 20, in one embodiment, afiber215 is shown entering asplayer2000 through a wall orside2005 and traversing a path through thesplayer2000 that provides slack2010. For ease of illustration and explanation,FIG. 20 is a top view of the interior of asplayer2000, and thecatheter120 is not shown, but would be positioned to the left of thesplayer2000. If thecatheter210 andfiber215 move outwardly to the left, some of thisslack2010 will be taken up or reduced. Slack2010 may also be provided in other ways and may be outside of thesplayer2000.
• Embodiments address another issue related to the position of thesplayer2000 in relation to the location of a FBG302 (FBGs are not illustrated inFIG. 20 for ease of illustration), e.g., a first FBG302(1), although not necessarily thefirst FBG302, which serves as areference FBG2020. In this embodiment, thereference FBG2020 is positioned such that its location is precisely known. In this manner, the location of thereference FBG2020 can be precisely known and is suitable for fiber based location measurement devices that depend on various small measurements that start from or based on the reference. For example, the location of a second. grating302 is measured in relation to thefirst grating302, the location of thethird grating302 is measured in relation to thesecond grating302, and so on. Thus if the absolute location of thereference grating2020 is not known in relation to some coordinate system, then the absolute position of asecond grating302 or the position of athird grating302 or any grating302 that is beyond thereference grating2020 is not known.
• In some cases, it may not be necessary to know the absolute positions of thegratings302; it may be only necessary to know the relative location of the second, third andother gratings302 in relation to thereference grating2020. in both of these cases where the absolute position or the relative position is required, it still is necessary to ensure that thereference grating2020 does not move, or if it does move, that some adjustment or accommodation is utilized to know the location of thereference grating2020.
• As shown inFIG. 20, afiber215 is attached to a wall of thesplayer2000, and a grating302, e.g. a first grating, is placed within thefiber215 at this “reference” location. This ensures that thereference grating2020, the first grating in this example, does not move relative to the wall of thesplayer2000. Since thesplayer2000 is a rigid component, the location of thereference grating2020 is precisely known.
• In an alternative embodiment, referring to FIG,21, a longfirst grating2102 is provided. A portion of thegrating2102 is in a rigidly placed sleeve2104 (which is also rigid). A portion of thegrating2102 is positioned within thesleeve2104, and a portion is positioned outside of thesleeve2104. In certain embodiments, amulti-core fiber215 hasmultiple cores304 that are spaced around the neutral axis of thefiber210. This arrangement ensures that sections of thefiber cores304 outside of thesleeve2104 that are bent will experience a different strain compared to sections of thecores304 that are inside of thesleeve2104 and that are linear or straight. Reflected light226 from thisgrating2102 contains two peaks. A first peak occurs at a frequency corresponding to the strain experienced by the portion of the grating2102 that is located outside of thesleeve2104, and a second peak occurs at a frequency corresponding to the strain experienced by the portions of the grating2102 that are located inside of thesleeve2104. The relative locations and the width of the grating2104 can be used to determine the exact position of thereference sensor2020.
• Yet other embodiments involve apparatus and methods for determining the position of the reference sensor or grating2020. External sensors, such as precision linear encoders, electromagnetic localization sensors, or potential-difference-based localization sensors may be attached at the location of thereference sensor2020. These sensors may then be utilized to provide the location of thereference sensor2020.
• As described above, minimally-invasive interventional and/or diagnostic systems often involve both disposable components (such as a splayer2000) and non-disposable components (such as a light source or instrument driver). In such a system, the integrity of the connection between the disposable component and a non-disposable component should be high. For this purpose, an integrity test can be performed by emitting light or a test signal into the disposable component and analyzing the light reflected there from. For example, the received signal226 from each grating302, particularly the first or reference grating2020 may be analyzed for various parameters, particularly for intensity. If the intensity is low, then the connector may be bad or the connection may not have been made properly. A warning can then be generated to warn the operator to check the connection.
• In a robotic surgical system that controls a minimally invasive elongate instrument orcatheter210, it is important to maintain the structural integrity of theinstrument210. If for example, mechanisms that control the navigation of theelongate instrument210 break, then the controllability of the system lay be compromised. To address these issues, in one embodiment, afiber215 is attached to an elongate instrument orcatheter210 to monitor such mechanical breakages. As thefiber210 based shape and location measurement device is attached to the elongate instrument orcatheter210, the shape of the instrument orcatheter210 can be monitored. If the shape is anomalous in some way indicating a breakage, then a warning is generated for the operator and the procedure may be stopped manually or automatically.
• Having described various apparatus and method embodiments in detail, further details of a robotic surgical systems and components thereof in which embodiments of the invention may be implemented are described with reference toFIGS. 22A-26B, andFIGS. 23A-B and26A-B illustrate how embodiments of th.e invention can be implemented and including various components of the robotic surgical system described. A description a system and methods for utilizing localization data for closed-loop control of a robotic catheter system in which embodiments may be implemented is provided with reference toFIGS. 22A-25F.
• Referring toFIGS. 22A-F, one example of a roboticsurgical system2200 in which embodiments of the invention that utilize anoptical fiber sensor215 may be implemented includes an operator work orcontrol station2205, which may be configured as, or include control, processor or computer software and/or hardware, which may perform various data processing functions on data from anoptical fiber sensor215 and execute various processing and control functions in response thereto.
• Theworkstation2205 is located remotely from an operating table2207, anelectronics rack2210, a setupjoint mounting brace2215, and motor-drivencontroller1200 in the form aninstrument driver2220. A surgeon oroperator2225 seated at theoperator workstation2205 monitors a surgical procedure,patient1500 vitals, and controls one or more flexible catheter assemblies that may include a coaxially-associated instruments of anouter sheath catheter220, an inner axially-associatedcatheter210 such as a guide catheter, and a workinginstrument240 such as a guidewire, a pusher ablation catheter, a laser ablation fiber, a grasper, a collapsible basket tool, etc., which is positioned within the working lumen defined by theinner catheter210.
• Although the various components of thesystem2200 are illustrated in close proximity to each other, components may also be separated from each other, e.g., in separate rooms. For example, theinstrument driver2220, the operating table2207 and a bedside electronics box may be located in the surgical area, whereas theoperator workstation2205 and the electronics rack2210 may be located outside of the surgical area behind a shielded partition.System2200 components may communicate with other components via a network, thus allowing for remote surgery such that thesurgeon2225 may be in the same or different building or hospital site. For this purpose, a communication link may be provided to transfer signals between theoperator control station2205 and theinstrument driver2220. Components may be coupled together viacables2230 as necessary for data communication. Wireless communications may also be utilized.
• Referring toFIG. 22B, onesuitable operator workstation2205 includes a console having one ormore display screens2232, which r ay serve asdisplay340, a master input device (MID)2234 and other components such as atouchscreen user interface2236, and dataglove input devices2238. TheMID2234 may be a multi-degree-of-freedom device that includes multiple joints and associated encoders.MID2234 software may be a proprietary module packaged with an off-the-shelf master input device system, such as the Phantom® from SensAble Technologies, Inc., which is configured to communicate with the Phantom® Haptic Device hardware at a relatively high frequency as prescribed by the manufacturer. Othersuitable MIDs2234 are available from suppliers such as Force Dimension of Lausanne, Switzerland. TheMID2234 may also have haptics capability to facilitate feedback to the operator, and software modules pertinent to such functionality may be operated on the master computer. An example ofdata glove software2244 is a device driver or software model such as a driver for the 5DT Data Glove. In other embodiments, software support for the data glove master input device is provided through application drivers such as Kaydara MOCAP,Discreet 3D Studio Max, Alias Maya, and SoftImage|XSI.
• Theinstrument driver2220 and associated flexible catheter assembly and working instruments may be controlled by anoperator2225 via the manipulation of theMID2234,data gloves2238, or a combination of thereof. During use, theoperator2225 manipulates a pendant andMID2234 to cause theinstrument driver2220 to remotely control flexible catheters that are mounted thereon. Inputs to theoperator workstation2205 to control the flexible catheter assembly can entered using the MID2223 and one ormore data gloves2238. TheMID2234 anddata gloves2238, which may be wireless, serve as user interfaces through which theoperator2225 may control the operation of theinstrument driver2220 and any instruments attached thereto. It should be understood that While anoperator2225 may robotically control one or more flexible catheter devices via an inputs device, a computer orother controller340 of therobotic catheter system2200 may be activated to automatically position acatheter instrument210 and/or itsdistal extremity211 inside of apatient1500 or to automatically navigate the patient anatomy to a designated surgical site or region of interest.
• Referring toFIG. 22C, a system architecture of arobotic catheter system2200 includes acontroller340 in the form of amaster computer2241 that manages operation of thesystem2200. Themaster computer2241 is coupled to receive user input from hardware input devices such as a dataglove input device2238 and ahaptic MID2234. Themaster computer2241 may execute MID hardware orsoftware2243,data glove software2244 and other software such as visualization software, instrument localization software, and software to interface with operator control station buttons and/or switches.Data glove software2244 processes data from the dataglove input device2238, and MID hardware/software2243 processes data from thehaptic MID2234. Themaster computer2241 or another computer or controller may also receive data from anoptical fiber sensor215.
• For example, in one embodiment, in response to the processed inputs, e.g., in response to the data or analysis of such data of detected reflectedlight signals326 from theoptical fiber sensor215, themaster computer2241 processes instructions toinstrument driver computer2242 to activate the appropriate mechanical response from the associated motors and mechanical components of thedriver2220 to achieve the desired response from the flexible catheter assembly including asheath220 and catheter orelongate instrument210.
• Further, in another embodiment, themaster computer2241 or other suitable computer or controller may control actuation of the at least one servo motor to activate the appropriate mechanical response from the associated motors and mechanical components of thedriver2220 to achieve the desired response from the flexible catheter assembly including asheath220 and catheter orelongate instrument210 based at least in part upon a comparison of an actual position the instrument derived from the localization data to a projected position of the instrument derived from a kinematic model of the instrument.
• As a further example, in one embodiment, themaster computer2241 or another suitable computer may be configured to determine patient respiration based onsignals326 received fromrespective Bragg gratings302 on the one or more Bragg sensoroptical fibers215. Thus, themaster computer2241 can coordinate control of one or more instruments, such as a catheter, monitor one or more instruments, and/or monitor a patient. For example, a controller orcomputer340 may be configured to determine one or more position and/or orientation variables of aninstrument driver2220, an instrument such as acatheter210, and a patient's body based on detected reflectedlight signals326 received from therespective Bragg gratings302 on thedifferent fibers215.
• In yet another embodiment, in response to the data or analysis of such data of detected reflectedlight signals326 from theoptical fiber sensor215, acontroller340 ormaster computer2241 may generate and display a graphical representation of an instrument body such as acatheter210 by depicting one or more position and/or orientation variables thereof based. upon reflected light signals326 received from the one or more Bragg gratings302.
• Referring toFIG. 22D, an example of a setup joint, instrument mounting brace or support assembly2250 (generally referred to as a support assembly2250) that supports theinstrument driver2220 above the operating table2207 is an arcuate-shaped structure configured. to position theinstrument driver2220 above apatient1500 lying on the table2207 for convenient access to desired locations relative to thepatient1500. Thesupport assembly2250 may also be configured to lock theinstrument driver2220 into position. In this example, thesupport assembly2250 is mounted to the edge of apatient bed2207 such that an assembly including acatheter210 mounted on theinstrument driver2220 can be positioned for insertion into apatient1500 and to allow for any necessary movement of theinstrument driver2220 in order to maneuver the catheter assembly during a surgical procedure.
• As shown inFIGS. 22A,22D,22E and22F, and as illustrated inFIG. 2A, a flexible catheter assembly for use in embodiments includes three coaxially-associated instruments including anouter sheath catheter220, an inner coaxially-associated catheter or guidecatheter210, and a working instrument (not illustrated inFIGS. 22A,22D,22E-F) such as a guidewire, pusher wire, ablation catheter, laser ablation fiber, grasper, collapsible basket tool, etc.—a myriad of small working tools may be utilized and localized) positioned through the working lumen formed by theinner catheter210.
• In the illustrated example, asplayer2261 having one or more control elements or pull wires and aflexible sheath member220 having a central lumen. Similarly, asplayer2262 located proximally of thesplayer2261 for thecatheter210 has one or more control elements or pull wires. Thecatheter instrument210 has a central lumen configured for passage of a working element orinstrument240. Prior to use, thecatheter210 is inserted into thesheath220 such that these components are coaxially positioned. Bothsplayers2261,2262 are mounted to respective mounting plates on theinstrument driver2220, and thesplayers2261,2262 are controlled to manipulate the catheter andsheath instruments210,220.
• In one embodiment, a system includes an elongate instrument orcatheter210 having one or more control elements or pull wires operatively coupled to at least one servo motor of the instrument driver2220 (e.g. as generally illustrated inFIGS. 12 and 13) such that theinstrument210 moves in response to actuation of the at least one servo motor. Theoptical fiber sensor215 supplies localization data indicative of a spatial position of at least a portion of theinstrument210, and thecontroller340 or other system control element controls actuation of the at least one servo motor in order to control movement of theinstrument210 based at least in part upon a comparison of an actual position theinstrument210 derived from the localization data to a projected position of the instrument derived from, for example, a kinematic model of theinstrument210.
• As shown in various system figures,optical fiber sensors215 can be coupled to or integral with various system components. In certain embodiments, anoptical fiber sensor215 is coupled to or integral with a catheter or elongate instrument210 (e.g., within alumen213 or lumen217), asheath220, theinstrument driver2220, the patient'sbed2207, and/or attached to thepatient1500. For example,FIG. 22A illustrates an embodiment in whichoptical fiber sensors215 are coupled to two system components (instrument driver2200 and a bed or table2207) and thepatient1500, and a catheter or otherelongate instrument210 may also include anoptical fiber sensor215. For ease of illustration, various figures Show anoptical fiber sensor215 and its associated system component without associated connectors, etc.
• FIGS. 23A-C illustrate anelongate catheter210 in the form of asheath catheter2302 through which another instrument such as aguide catheter2304 may extend. According to embodiments,optical fiber sensors215 can be coupled to or integral with thesheath catheter2302 and/or theguide catheter2304, e.g., positioned within a suitable lumen or extending through a wall of an instrument. In the illustrated embodiment, the sheath catheter includes multiple segments2310(a-n) (generally segment2310). Eachsegment2310 may be generally the same shape, e.g. round ring-like structures, but may differ to some degree.Segments2310 can also be other shapes, e.g., square, rectangular, triangular, pentagonal, hexagonal, octagonal, circular, spherical, elliptical, star, etc. Pullwires2320 are operably coupled to eachsegment2310 and extend through aligned passages, apertures orchannels2314 defined by a wall of eachsegment2310. For example, apull wire2320 may be coupled to a distalmost segment2310 such that placing thepull wire2320 in tension also places moreproximal segments2310 in tension. In another embodiment, thepull wires2320 can be attached to some or all of thesegments2310, e.g., attached to an exterior surface of asegment2310.
• In certain embodiments, the wall of eachsegment2310 can also define an aperture213 (as illustrated inFIG. 2) for anoptical fiber sensor215. In this manner, control elements or pullwires2320 andoptical fiber sensors215 are advantageously routed through the body or wall ofsegments2320 rather than through an inner or central lumen defined by a collection ofsegments2320. In this manner, embodiments advantageously reduce the components extending through the inner or central lumen, thereby providing more space through which other instruments and devices, such as aguide catheter2304 and/or workinginstrument240 may be inserted. Instruments can also be advanced through thesheath catheter2302 more easily since thecontrol elements2320 andoptical fiber sensor215 do not interfere with these components. In an alternative embodiment, anoptical fiber sensor215 extends through an inner or central lumen defined by the collection ofsegments2320.
• Individual segments2320 of asheath catheter2302 having shaped, interlocking top and bottom surfaces that allowsegment2320 to matingly engageadjacent segments2320. In the illustrated embodiment, eachsegment2320 includes mating teeth orprotrusions2326 and notches orgrooves2328 that matingly engagement each other such that interlockingsegments2320 are not rotatable relative to each other. In this manner, aligned interlockingsegments2320 collectively define a catheter orelongate body structure120 that defines a lumen that extends through the plurality ofsegment2320 bodies. While the figures illustrate a structural configuration of one embodiment of asegment2320, other numbers and arrangements of teeth orprotrusions2326, notches orgrooves2328 andapertures2314,213 forcontrol elements2320 andoptical fiber sensors215 may be utilized. Further,individual segments2320 may have different numbers of teeth or protrusions and notches depending on the need to provide additional stability, support, and rigidity to thesheath catheter2302 when thesheath catheter2302 is deployed.
• With thesheath2302 configuration illustrated,segments2320 and be placed in tension to place the group ofsegments2320 in tension or a rigid state, or placed in a relaxed, low tension or flexible state. Thus, one embodiment of a catheter orelongate instrument120 in the form of asheath catheter2302 that may include an optical fiber sensor has controllable rigidity and can form a platform from which other instruments can extend and be controlled and provide rigidity and resistance to twisting or rotational loads on thesheath catheter2302.
• In addition to having anoptical fiber sensor215 as shown inFIG. 23A, a reference sensor may also be coupled to thesheath2302 proximate the distal end opening. With this configuration, one or more position and/or orientation variables of the distal end portions of the respective instrument bodies are determined relative to the reference sensor.
• With continuing reference toFIG. 23A, and with further reference toFIGS. 24A-D, arotatable apparatus2330 is coupled to thesheath catheter2302 and provides greater degrees of freedom and movement of aguide catheter2304, anorientation platform2340 and/or workinginstrument240 coupled thereto or associated therewith. Arotatable apparatus2330 may include an interface orwire guide apparatus2331 and a rotatable collar, tool base or wire receiveapparatus2332 which are rotatably coupled together. Thus, a tool or other system component may be rotatably coupled to a distal end portion of a medical instrument, such as a sheath or guidecatheter2302, by manipulation of one or more control elements207 that extend through grooves formed withinrotatable apparatus2330 to rotate thecollar component2332 clockwise (FIG. 24C) and counter-clockwise (FIG. 24D).
• As shown inFIGS. 24A-D, outer surfaces of the interface andcollar components2331,2332 defines one or more guides, channels orgrooves2402 that serve to guide, direct or route control element2320 (twocontrol elements2320a,bare illustrated). In the illustrated embodiment,control elements2302 wrap around a substantial portion of therotatable collar2331 such that manipulation of control elements207 results in rotation of therotatable collar2332.FIG. 23C further illustrates how various control elements207 may extend through asheath catheter2302 are connected to different components. Thus, pulling or placing tension on thecontrol element2320 rotates thecollar2332 and associated instruments such as aguide catheter2304 and workinginstrument240, thereby advantageously providing rotational control as well as articulation control of system components.
• Referring toFIG. 23A, and with further reference toFIGS. 25A-F, anorientation platform2340 of a robotic instrument system is configured to control a working instrument240 (one example of which is illustrated) coupled to a distal end of acatheter instrument2304 or other instrument of a robotic medical system, e.g., asheath220 coveredcatheter210. In the illustrated, example, the interface orplatform2340 includes a base member orsocket plate2502 configured for coupling to a distal end of catheter instrument member, aspacer element2504 and another socket plate orplatform member2506. Thespacer element2504 is retained or interposed between, and separates, thebase member2502 and theplatform member2506. Theplatform member2506 is movable relative to thebase member2502 about thespacer element2504. The interface orplatform2506 also includes acontrol element2320, such as a pull wire, that extends through the catheter member, through an aperture defined by thebase member2502, and terminating at theplatform member2506. Theplatform2340 may be used to control an orientation of theplatform ember2506 and an orientation of the workinginstrument240 are controllably adjustable by manipulation of thecontrol member2320.
• Further aspects of system components illustrated inFIGS. 23A-25F are described in various applications previously incorporated by reference.
• FIG. 26A illustrates another manner in which embodiments may be implemented in which multipleoptical fiber sensors215 are coupled to or integral with multiple catheters coupled to respective rotatable apparatus and orientation apparatus components described above, and which are advanced through an outer ormaster sheath2600.
• In the illustrated embodiment, eachsheath catheter2302 or a sub-portion thereof is localized utilizing anoptical fiber sensor215 which may be a Fiber Bragg Grating localization sensor. Other system components, such as an image capture device1400 (as shown inFIG. 26B) may also be localized with anoptical fiber sensor215. Further, similar to other embodiments discussed above, other system components, such as aninstrument driver2220 andpatient bed1500 may also haveoptical fiber sensors215. With this configuration, embodiments enable the entire environment (image capture device, each flexible arm, the main proximal arm, etc.) to be well characterized in near-real time, and the images from theimage capture device1400, such as a fluoroscopy device, may be appropriately associated with representations, cartoons and images produced from the depicted devices. Thus, embodiments provide apparatus and methods for combining or fusing a shape andlocalization measuring fiber215 and robotic surgical system components.
• Additionally, similar to apparatus and method embodiments discussed above,optical fiber sensors215 coupled to each system component may provide for determining and displaying the orientation and the roll of the tip of the elongate instruments. This is particularly useful when planning surgery or placing leads.
• Further, as shown inFIGS. 26A-B, a common reference device, or “control ring”2602 is provided at the distal end of themaster sheath2600 or sheath like structure that carries the elongate instruments includingsheath catheters2302 and guidecatheters2304. Thiscontrol ring2602 can be used as a common reference for all thefibers215 on elongate instruments, image capture devices, and the like which may extend distally from thecontrol ring2602 location. This common reference establishes a common coordinate frame for all thefibers215 such that the shape and location of thefibers215 may be measured in relation to thecontrol ring2602. This arrangement is particularly advantageous because the accuracy at the tip will be high due to the short length of thefiber215 run, the twist and roll of the elongate instruments may result in smaller errors since the distance between thecontrol ring2602 and the tip is short, and the elongate instruments are all in the same coordinate frame, which also improves accuracy compared to use of different coordinate frames.
• The location of thecontrol ring2602 may be localized in the world coordinate system by a separate fiber215 (single or multiple core), which is helpful if elongate instruments, such ascatheters2302,2304,image capture device1400 platforms, and the like, which extend distally beyond thecontrol ring2602, are coordinated with other external medical imaging or data processing systems, such as fluoroscopy systems, magnetic resonance imaging systems, or geometric and/or electronic mappings and datasets.
• For embodiments in which multipleelongate instruments2302 and/or2304 carry single tools, a single elongate instrument carries multiple tools, or multiple elongate instruments each carry multiple tools, fiber based shape andlocation measurement devices215 may be mechanically associated with each tool or each elongate instrument or to both. It is not necessary that all tools or elongate instruments have afiber215 attached or coupled thereto. Eachfiber215 could be a single core Bragg grating sensor fiber or a multiple core fiber Bragg grating sensor. More than one fiber may be used per tool or per elongate instrument or catheter.
• Accordingly,FIGS. 23A-C and26A-B are provided to illustrate different ways embodiments can be implemented. It should he understood that an instrument may include other numbers ofsheath catheters2302, other numbers ofguide catheters2304, and that eachcatheter210 having anoptical fiber sensor215 coupled thereto may have fibers of various lengths, positions and configurations.
• Additionally, embodiments described above can be utilized with various manually or robotically steerable instruments, various localization systems and rendering of images to assist an operator, including those systems and methods described in the aforementioned patent application, U.S. application Ser. No. 11/637,951, the contents of which were previously incorporated herein by reference.FIGS. 27-43 are provided for reference and illustrate one example of a localization system that utilizes localization data for closed-loop control of a robotic catheter system in which embodiments of the invention may be implemented, andFIGS. 44-49 are provided for reference and illustrate one example of user interface presentation of captured or “cartoon” rendered images that are used to assist the operator in controlling a robotic catheter system or the like. Additional details regarding these systems are omitted for clarity and described in further detail in application Ser. No. 11/637,951. Embodiments may also utilize other known localization and user interface presentation systems, and the systems and related methods shown inFIGS. 27-43 are provided as illustrative examples that may be used with embodiments.
• FIGS. 27-37 depict various aspects of one embodiment of a SimuLink® software control schema for an embodiment of a physical system, with particular attention to an embodiment of a “master following mode.” In this system, an instrument is driven by following instructions from a MID, and a motor servo loop embodiment, which comprises key operational functionality for executing upon commands delivered from the master following mode to actuate the instrument.
• FIG. 27 depicts a high-level view of an embodiment wherein any one of three modes may be toggled to operate theprimary servo loop2702. Inidle mode2704, the default mode when the system is started up, all of the motors are commanded via themotor servo block2706 to servo about their current positions, their positions being monitored with digital encoders associated with the motors. In other words,idle mode2704 deactivates the motors, while the remaining system stays active. Thus, when the operator leaves idle mode, the system knows the position of the relative components. Inauto home mode2708, cable loops within an associated instrument driver, such as theinstrument driver2220, are centered within their cable loop range to ensure substantially equivalent range of motion of an associated instrument, such as a catheter, in both directions for a various degree of freedom, such as + and − directions of pitch or yaw, when loaded upon the instrument driver. This is a setup mode for preparing an instrument driver before an instrument is engaged.
• Inmaster following mode2710, the control system receives signals from the master input device, and in a closed loop embodiment from both a master input device and a localization system, and forwards drive signals to theprimary servo loop2702 to actuate the instrument in accordance with the forwarded commands. Aspects of this embodiment of themaster following mode2710 are depicted in further detail inFIGS. 32-37. Aspects of the primary servo loop andmotor servo block2706 are depicted in further detail inFIGS. 28-31.
• Referring toFIG. 32, a more detailed functional diagram of an embodiment ofmaster following mode2710 is depicted. As shown inFIG. 32, the inputs tofunctional block3202 are XYZ position of the master input device in the coordinate system of the master input device which, per a setting in the software of the master input device may be aligned to have the same coordinate system as the catheter, and localization XYZ position of the distal tip of the instrument as measured by the localization system in the same coordinate system as the master input device and catheter. Referring toFIG. 33, for a more detailed view offunctional block3202 ofFIG. 32, aswitch3302 is provided at block to allow switching between master inputs for desired catheter position, to aninput interface3304 through which an operator may command that the instrument go to a particular XYZ location in space. Various controls features may also utilize this interface to provide an operator with, for example, a menu of destinations to which the system should automatically drive an instrument, etc. Also depicted inFIG. 33 is a master scalingfunctional block3306 which is utilized to scale the inputs coming from the master input device with a ratio selectable by the operator. Thecommand switch3302 functionality includes a low pass filter to weight commands switching between the master input device and theinput interface3304, to ensure a smooth transition between these modes.
• Referring back toFIG. 32, desired position data in XYZ terms is passed to the inverse kinematics block3206 for conversion to pitch, yaw, and extension (or “insertion”) terms in accordance with the predicted mechanics of materials relationships inherent in the mechanical design of the instrument.
• The kinematic relationships for many catheter instrument embodiments may be modeled by applying conventional mechanics relationships, in summary, a control-element-steered catheter instrument is controlled through a set of actuated inputs. In a four-control-element catheter instrument, for example, there are two degrees of motion actuation, pitch and yaw, which both have + and − directions. Other motorized tension relationships may drive other instruments, active tensioning, or insertion or roll of the catheter instrument. The relationship t, between actuated inputs and the catheter's end point position as a function of the actuated inputs is referred to as the “kinematics” of the catheter.
• Referring toFIG. 38, the “forward kinematics” expresses the catheter's end-point position as a function of the actuated inputs while the “inverse kinematics” expresses the actuated inputs as a function of the desired end-point position. Accurate mathematical models of the forward and inverse kinematics are essential for the control of a robotically controlled catheter system. For clarity, the kinematics equations are further refined to separate out common elements, as shown inFIG. 38. The basic kinematics describes the relationship between. the task coordinates and the joint coordinates. In such case, the task coordinates refer to the position of the catheter end-point while the joint coordinates refer to the bending (pitch and yaw, for example) and length of the active catheter. The actuator kinematics describes the relationship between the actuation coordinates and the joint coordinates. The task, joint, and bending actuation coordinates for the robotic catheter are illustrated inFIG. 39. By describing the kinematics in this way we can separate out the kinematics associated with the catheter structure, namely the basic kinematics, from those associated with the actuation methodology.
• The development of the catheter's kinematics model is derived using a few essential assumptions. Included are assumptions that the catheter structure is approximated as a simple beam in bending from a mechanics perspective, and that control elements, such as thin tension wires, remain at a fixed distance from the neutral axis and thus impart a uniform moment along the length of the catheter.
• In addition to the above assumptions, the geometry and variables shown inFIG. 40 are used in the derivation of the forward and inverse kinematics. The basic forward kinematics relates catheter task coordinates to joint coordinates, as expressed in further detail in U.S. application Ser. No. 11/637,951. The actuator forward kinematics, relating the joint coordinates to the actuator coordinates are also expressed in application Ser. No. 11/637,951
• As illustrated inFIG. 38, the catheter's end-point position can be predicted given the joint or actuation coordinates by using the forward kinematics equations described above. Calculation of the catheter's actuated inputs as a function of end-point position, referred to as the inverse kinematics, can be performed numerically, using a nonlinear equation solver such as Newton-Raphson. A more desirable approach, and the one used in this illustrative embodiment, is to develop a closed-form solution which can be used to calculate the required actuated inputs directly from the desired end-point positions.
• As with the forward kinematics, we separate the inverse kinematics into the basic inverse kinematics, which relates joint coordinates to the task coordinates, and the actuation inverse kinematics, which relates the actuation coordinates to the joint coordinates. The basic inverse kinematics, relating the joint coordinates to the catheter task coordinates is expressed in application Ser. No. 11/637,951. The actuator inverse kinematics, relating the actuator coordinates to the joint coordinates is also expressed in application Ser. No. 11/637,951.
• Referring back toFIG. 32, pitch, yaw, and extension commands are passed from the inverse kinematics block3206 to aposition control block3204 along with measured localization data.FIG. 37 provides a more detailed view of theposition control block3204. After measured XYZ position data comes in from the localization system, it goes through aninverse kinematics block3702 to calculate the pitch, yaw, and extension the instrument needs to have in order to travel to where it needs to be. Comparing3704 these values with filtered desired pitch, yaw, and extension data from the master input device, integral compensation is then conducted with limits on pitch and yaw to integrate away the error. In this embodiment, the extension variable does not have thesame limits3706, as do pitch andyaw3708. As will be apparent to those skilled, in the art, having an integrator in a negative feedback loop forces the error to zero. Desired pitch, yaw, and extension commands are next passed through a catheterworkspace limitation block3208, which may be a function of the experimentally determined physical limits of the instrument beyond which componentry may fail, deform undesirably, or perform unpredictably or undesirably. This workspace limitation essentially defines a volume similar to a cardioid-shaped volume about the distal end of the instrument. Desired pitch, yaw, and extension commands, limited by the workspace limitation block, are then passed to a catheterroll correction block3210.
• This functional block is depicted in further detail inFIG. 34, and essentially comprises a rotation matrix for transforming the pitch, yaw, and extension commands about the longitudinal, or “roll”, axis of the instrument—to calibrate the control system for rotational deflection at the distal tip of the catheter that may change the control element steering dynamics. For example, if a catheter has no rotational deflection, pulling on a control element located directly up at twelve o'clock should urge the distal tip of the instrument upward. If, however, the distal tip of the catheter has been rotationally deflected by, say, ninety degrees clockwise, to get an upward response from the catheter, it may be necessary to tension the control element that was originally positioned at a nine o'clock position. The catheter roll correction schema depicted inFIG. 34 provides a means for using a rotation matrix to make such a transformation, subject to a roll correction angle, such as the ninety degrees in the above example, which is input, passed through a low pass filter, turned to radians, and put through rotation matrix calculations.
• In one embodiment, the roll correction angle is determined through experimental. experience with a particular instrument and path of navigation. In another embodiment, the roll correction angle may be determined experimentally in-situ using the accurate orientation data available from the preferred localization systems. In other words, with such an embodiment, a command to, for example, bend straight up can be executed, and a localization system can be utilized to determine at which angle the defection actually went—to simply determine the in-situ roll correction angle.
• Referring briefly back toFIG. 32, roll corrected pitch and yaw commands, as well as unaffected extension commands, are output from the catheterroll correction block3210 and may optionally be passed to a conventionalvelocity limitation block3212. Referring toFIG. 35, pitch and yaw commands are converted from radians to degrees, and automatically controlled roll may enter the controls picture to complete the current desiredposition3502 from the last servo cycle. Velocity is calculated by comparing the desired position from the previous servo cycle, as calculated with a conventionalmemory block calculation3506, with that of the incoming commanded cycle. Aconventional saturation block3504 keeps the calculated velocity within specified values, and the velocity-limitedcommand3506 is converted back to radians and passed to atension control block3514.
• Tension within control elements may be managed depending upon the particular instrument embodiment, as described above in reference to the various instrument embodiments and tension control mechanisms. As an example,FIG. 36 depicts apre-tensioning block3602 with which a given control element tension is ramped to a present value. An adjustment is then added to the original pre-tensioning based upon a preferably experimentally-tuned matrix pertinent to variables, such as the failure limits of the instrument construct and the incoming velocity-limited pitch, yaw, extension, and roll commands. This adjusted. value is then added3604 to the original signal for output, via gear ratio adjustment, to calculate desired motor rotation commands for the various motors involved with the instrument movement. In this embodiment, extension, roll, andsheath instrument actuation3606 have no pre-tensioning algorithms associated with their control, The output is then complete from the master following mode functionality, and this output is passed to theprimary servo loop2702.
• Referring back toFIG. 27, incoming desired motor rotation commands from either themaster following mode2710,auto home mode2708, oridle mode2704 in the depicted embodiment are fed into amotor servo block2706, which is depicted in greater detail inFIGS. 28-31.
• Referring toFIG. 28, incoming measured motor rotation data from digital encoders and incoming desired motor rotation commands are filtered using conventional quantization noise filtration at frequencies selected for each of the incoming data streams to reduce noise while not adding undue delays which may affect the stability of the control system. As shown inFIGS. 30-31, conventional quantization filtration is utilized on the measured motor rotation signals at about 200 hertz in this embodiment, and on the desired motor rotation command at about 15 hertz. Thedifference2804 between the quantization filtered values forms the position error which may be passed through a lead filter, the functional equivalent of a proportional derivative (“PD”)+low pass filter. In another embodiment, conventional PID, lead/lag, or state space representation filter may be utilized. The lead filter of the depicted embodiment is shown in further detail inFIG. 29.
• In particular, the lead filter embodiment inFIG. 29 comprises a variety of constants selected to tune the system to achieve desired performance. The depicted filter addresses the needs of one embodiment of a 4-control element guide catheter instrument with independent control of each of four control element interface assemblies for +/−pitch and +/−yaw, and separate roll and extension control. As demonstrated in the depicted embodiment, insertion and roll have different inertia and dynamics as opposed to pitch and yaw controls, and the constants selected to tune them is different. The filter constants may be theoretically calculated using conventional techniques and tuned by experimental techniques, or wholly determined by experimental techniques, such as setting the constants to give a sixty degree or more phase margin for stability and speed of response, a conventional phase margin value for medical control systems.
• In an embodiment where a tuned master following mode is paired with a tuned primary servo loop, an instrument and instrument driver, such as those described above, may be “driven” accurately in three-dimensions with a remotely located Master input device. Other preferred embodiments incorporate related functionalities, such as haptic feedback to the operator, active tensioning with a split carriage instrument driver, navigation utilizing direct visualization and/or tissue models acquired in-situ and tissue contact sensing, and enhanced navigation logic.
• Referring toFIG. 39, in one embodiment, the master input device may be a haptic master input device, such as those available from SensAble Technologies, Inc., under the trade name Phantoms® Haptic Devices, and the hardware and software required for operating such a device may at least partially reside on the master computer. The master XYZ positions measured from the master joint rotations and forward kinematics are generally passed to the master computer via a parallel port or similar link and may subsequently be passed to a control and instrument driver computer. With such an embodiment, an internal servo loop for a Phantoms® Haptic Device generally runs at a much higher frequency in the range of 1,000 Hz, or greater, to accurately create forces and torques at the joints of the master.
• Referring toFIG. 42, a sample flowchart of a series of operations leading from a position vector applied at the master input device to a haptic signal applied back at the operator is depicted. Avector4202 associated with a master input device move by an operator may be transformed into an instrument coordinate system, and in particular to a catheter instrument tip coordinate system, using asimple matrix transformation4204. The transformedvector4206 may then be scaled4208 per the preferences of the operator, to produce a scaled-transformedvector4210. The scaled-transformed vector may be sent to both the control andinstrument driver computer4212 preferably via a serial wired connection, and to the master computer for acatheter workspace check4214 and any associatedvector modification4216. This is followed by a feedbackconstant multiplication4218 chosen. to produce preferred levels of feedback, such as force, in order to produce a desiredforce vector4220, and aninverse transform4222 back to aforce vector4224 in the master input device coordinate system for associated haptic signaling to the operator in that coordinate system.
• A conventional Jacobin may be utilized to convert a desiredforce vector4220 to torques desirably applied at the various motors comprising the master input device, to give the operator a desired signal pattern at the master input device. Given this embodiment of a suitable signal and execution pathway, feedback to the operator in the form of haptics, or touch sensations, may be utilized in various ways to provide added safety and instinctiveness to the navigation features of the system, as discussed in further detail below.
• FIG. 43 is a system block diagram including haptics capability. As shown in summary form inFIG. 43, encoder positions on the master input device, changing in response to motion at the master input device, are measured4302, sent throughforward kinematics calculations4304 pertinent to the master input device to get XYZ spatial positions of the device in the master input device coordinatesystem4306, then transformed4308 to switch into the catheter coordinate system and (perhaps) transform for visualization orientation and preferred controls orientation, to facilitate “instinctive driving”.
• The transformed desiredinstrument position4310 may then be sent down one or more controls pathways to, for example, provide haptic feedback4312 regarding workspace boundaries or navigation issues, and provide a catheter instrumentposition control loop4314 with requisite catheter desired position values, as transformed utilizingcatheter inverse4316 kinematics relationships for the particular instrument into yaw, pitch, and extension, or insertion,terms4318 pertinent to operating the particular catheter instrument with open or closed loop control.
• As further reference, referring toFIG. 44, a systemic view configured to produce an overlaid image is depicted. A knownfluoroscopy system4402 outputs an electronic image in formats such as those known as “S-video” or “analog high-resolution video”. Inimage output interface4404 of afluoroscopy system4402 may be connected to an input interface of acomputer4410 based image acquisition device, such as those known as “frame grabber”4412 image acquisition cards, to facilitate intake of the video signal from thefluoroscopy system4402 into theframe grabber4412, which may be configured to produce bitmap (“BMP”) digital image data, generally comprising a series of Cartesian pixel coordinates and associated grayscale or color values which together may be depicted as an image. The bitmap data may then be processed utilizing computer graphics rendering algorithms, such as those available in conventional OpenGL,graphics libraries4414. In summary, conventional OpenGL functionality enables a programmer or operator to define object positions, textures, sizes, lights, and cameras to produce three-dimensional renderings on a two-dimensional display. The process of building a scene, describing objects, lights, and camera position, and using OpenGL, functionality to turn such a configuration into a two-dimensional image for display is known in computer graphics as rendering. The description of objects may be handled by forming a mesh of triangles, which conventional graphics cards are configured to interpret and output displayable two-dimensional images for a conventional display or computer monitor, as would be apparent to one skilled in the art. Thus theOpenGL software4414 may be configured to send rendering data to thegraphics card4416, which may then be output aconventional display4420.
• A triangular mesh generated with OpenGL software may be used to form a cartoon-like rendering of an elongate instrument moving in space according to movements from, for example, a master following mode operational state, may be directed to a computer graphics card, along with frame grabber and OpenGL processed fluoroscopic video data. Thus a moving cartoon-like image of an elongate instrument would be displayable. To project updated fluoroscopic image data onto a flat-appearing surface in the same display, a plane object, conventionally rendered by defining two triangles, may be created, and the updated fluoroscopic image data may he texture mapped onto the plane. Thus the cartoon-like image of the elongate instrument may be overlaid with the plane object upon which the updated fluoroscopic image data is texture mapped. Camera and light source positioning may be pre-selected, or selectable by the operator through the mouse or other input device, for example, to enable the operator to select desired image perspectives for his two-dimensional computer display. The perspectives, which may be defined as origin position and vector position of the camera, may be selected to match with standard views coming from a fluoroscopy system, such as anterior/posterior and lateral views of a patient lying on an operating table. When the elongate instrument is visible in the fluoroscopy images, the fluoroscopy plane object and cartoon instrument object may be registered with each other by ensuring that the instrument depicted in the fluoroscopy plane lines up with the cartoon version of the instrument. in one embodiment, several perspectives are viewed while the cartoon object is moved using an input device such as a mouse, until the cartoon instrument object is registered with the fluoroscopic plane image of the instrument. Because both the position of the cartoon object and fluoroscopic image object may be updated in real time, an operator, or the system automatically through image processing of the overlaid image, may interpret significant depicted mismatch between the position of the instrument cartoon and the instrument fluoroscopic image as contact with a structure that is inhibiting the normal predicted motion of the instrument, error or malfunction in the instrument, or error or malfunction in the predictive controls software underlying the depicted position of the instrument cartoon.
• Referring back toFIG. 44, other video signals (not shown) may be directed to theimage grabber4412, besides that of afluoroscopy system4402, simultaneously. For example, images from an intracardiac echo ultrasound (“ICE”) system, intravascular ultrasound (“IVUS”), or other system may be overlaid onto the same displayed image simultaneously. Further, additional objects besides a plane for texture mapping fluoroscopy or an elongate instrument cartoon object may be processed using OpenGL or other rendering software to add additional objects to the final display.
• Referring toFIGS. 45A-B and46, an elongate instrument is a robotic guide catheter, and fluoroscopy and ICE are utilized to visualize the cardiac and other surrounding tissues, and instrument objects. Referring toFIG. 45A, a fluoroscopy image has been texture mapped upon a plane configured to occupy nearly the entire display area in the background. Visible in the fluoroscopy image as a dark elongate shadow is the actual position, from fluoroscopy, of the guide catheter instrument relative to the surrounding tissues. Overlaid in front of the fluoroscopy plane is a cartoon rendering (white in color inFIGS. 45A-B) of the predicted, or “commanded”, guide catheter instrument position. Further overlaid in front of the fluoroscopy plane is a small cartoon object representing the position of the ICE transducer, as well as another plane object adjacent the ICE transducer cartoon object onto which the ICE image data is texture mapped by a technique similar to that with which the fluoroscopic images are texture mapped upon the background plane object. Further, mouse objects, software menu objects, and many other objects may be overlaid.FIG. 45A shows a similar view with the instrument in a different position. For illustrative purposes,FIGS. 45A-B depict misalignment of the instrument position from the fluoroscopy object, as compared with the instrument position from the cartoon object. As described above, the various objects may be registered to each other by manually aligning cartoon objects with captured image objects in multiple views until the various objects are aligned as desired, image processing of markers and shapes of various objects may be utilized to automate portions of such a registration process.
• Referring toFIG. 46, a schematic is depicted to illustrate how various objects, originating from actual medical images processed by frame grabber, originating from commanded instrument position control outputs, or originating from computer operating system visual objects, such as mouse, menu, or control panel objects, may be overlaid into the same display.
• Further, a pre-acquired image of pertinent tissue, such as a three-dimensional image of a heart, may be overlaid and registered to updated images from real-time medical imaging modalities as well. For example, in one embodiment, a beating heart may be preoperatively imaged using gated computed tomography (CT). The result of CT imaging may be a stack of CT data slices. Utilizing either manual or automated thresholding techniques, along with interpolation, smoothing, and/or other conventional image processing techniques available in software packages such as that sold under the tradename Amira® product available from Mercury Computer Systems of Chelmsford, Mass., a triangular mesh may be constructed to represent a three-dimensional cartoon-like object of the heart, saved, for example, as an object (“.obj”) file, and added to the rendering as a heart object. The heart object may then be registered as discussed above to other depicted images, such as fluoroscopy images, utilizing known tissue landmarks in multiple views, and contrast agent techniques to particularly see show certain tissue landmarks, such as the outline of an aorta, ventricle, or left atrium. The cartoon heart object may be moved around, by mouse, for example, until it is appropriately registered in various views, such as anterior/posterior and lateral, with the other overlaid objects.
• Referring toFIG. 47, a distributed system architecture embodiment is depicted. A master control computer running a real-time operating system, such as QNX, is connected to each of the other computers in the system by a 1 gigabit Ethernet “Real-time Network”, and also by a 100 megabit Ethernet “System Network”, using a conventional high-speed switch. This enables localized custom computing for various devices to be pushed locally near the device, without the need for large cabling or a central computing machine. In one embodiment, the master control computer may be powered by an Intel® Xeon® processor available from Intel Corporation of Santa Clara, Calif., the visualization computer powered by a personal computer (PC) with a high-end microprocessor based on the Intel architecture running Windows XP and having multiple video cards and frame grabbers, the instrument driver and master input device CPUs being PC or “EPIC” standard boards with two Ethernet connections for the two networks. An additional master input device, touchscreen, and console may be configured into an addition operator workstation in a different location relative to the patient. The system is very expandable—new devices may be plugged into the switch and placed onto either of the networks.
• Referring toFIG. 47, two high resolution frame grabber boards4702 acquire images from two fluoro devices (or one in the case of single plane fluoro), Which a nominal resolution frame grabber board4702 acquires images from an intracardiac echo system. Such image data may be utilized for overlaying, etc., as described in reference toFIGS. 44-46, and displayed on a display, such as the #2 display, using avideo card4704 of the visualization computer, as depicted. Heart monitor data, from a system such as the Prucka CardioLab EP System distributed by GE Healthcare of Waukesha, Wis., may be directly channeled from video out ports on the heart monitor device to one of the displays. Such data may also be acquired by a frame grabber. Similarly, electrophysiological mapping and treatment data and images from systems available from distributors such as Endocardial Solutions, Biosense Webster, Inc., etc., may be directed as video to a monitor, or data to a data acquisition board, data bus, or frame grabber. Preferably the master control computer has some interface connectivity with the electrophysiology system as well to enable single master input device driving of such device, etc.
• Referring toFIG. 48, a depiction of the software and hardware interaction is depicted. Essentially, the master state machine functionality of the master control system real-time operating system allows for very low latency control of processes used to operate master input device algorithms and instrument driver algorithms, such as those described in reference to the control systems description above. Indeed, XPC may be utilized to develop algorithm code, but preferably a universal modeling language such as IBM Rational Rose from IBM Corporation of Armonk, N.Y., or Rhapsody of I-Logix of Andover, Mass., is utilized to build code and documentation using a graphical interface. With the gigabit real-time network, in a matter of 200-300 microseconds, the master input device or instrument driver algorithms are able to communicate with FPGA driver code in the electronics and hardware near the pertinent device to exchange new values, etc., and confirm that all is well from a safety perspective. This leaves approximately 700 microseconds for processing if a 1 millisecond motor shutoff time is required if all is not well—and this is easily achievable with the described architecture. The visualization PC may be configured to cycle data from the master control computer at a lower frequency, about 200 milliseconds.FIG. 49 illustrates the software interaction of one embodiment.
• Although particular embodiments have been shown and described, it should he understood that the above discussion is not intended to limit the scope of these embodiments. While embodiments and variations of the many aspects of the invention have been disclosed and described herein, such disclosure is provided for purposes of explanation and illustration only. Many combinations and permutations of the disclosed embodiments are useful in minimally invasive surgery, and the system is configured to be flexible for use with other system components and in other applications. Thus, various changes and modifications may be made without departing from the scope of the claims.
• For example, although embodiment are described with reference to a telemanipulation system or robotic control system, embodiments may also be manually controlled by a surgeon, e.g., near the proximal section of the sheath catheter Embodiments are advantageously suited for minimally invasive procedures, they may also be utilized in other, more invasive procedures that utilize extension tools and may be used in surgical procedures other than treatment of arrhythmias such as atrial fibrillation.
• Further, although embodiments are described, with reference to a fiber or fiber sensor coupled to or integral with a catheter, embodiments may also involve a fiber or fiber sensor coupled to or integral with a sheath, multiple catheters or other elongate instruments, e.g., that extend through a sheath, a working instrument, and other system components such as an a localization sensor, an instrument driver, a patient's bed, a patient, and combinations thereof. Further, such fibers may be positioned within an elongate instrument or coupled to or integral with an outer surface thereof.
• Moreover, depending on the configuration of a system and system components, a “controller” may be or include a unit coupled. to a fiber, may be, or include, a computer or processor of a robotic instrument system (e.g., in an electronics rack or at a user workstation), or a combination thereof. Further, a unit that sends and/or receives light may be a separate component or integrated within a controller component of a robotic instrument system. Thus, a “controller” may be a standalone or integrated component or include multiple components that are operably coupled together.
• Further, it should be understood that embodiments of an optical fiber sensor and apparatus, system and methods including or involving the same may be used in various applications and be configured in various different ways. For example, they may be coupled to or integral with various system components intended for insertion into a patent and that are intended for external use. Optical fiber sensors may also include various numbers of FBGs, which may be of the same or different wavelengths, and may be arranged in different ways. Further, various optical systems can be used with embodiments, and the exemplary components and read out system are provided as one example of how embodiments may be implemented.
• Because one or more components of embodiments may be used in minimally invasive surgical procedures, the distal portions of these instruments may not be easily visible to the naked eye. As such, embodiments of the invention may be utilized with various imaging modalities such as magnetic resonance (MR), ultrasound, computer tomography (CT), X-ray, fluoroscopy, etc. may be used to visualize the surgical procedure and progress of these instruments. It may also be desirable to know the precise location of any given catheter instrument and/or tool device at any given moment to avoid undesirable contacts or movements. Thus, embodiments may be utilized with localization techniques that are presently available may be applied to any of the apparatuses and methods disclosed above, Further, a plurality of sensors, including those for sensing patient vitals, temperature, pressure, fluid flow, force, etc., may be combined with the various embodiments of flexible catheters and distal orientation platforms.
• Various system components including catheter components may be made with materials and techniques similar to those described in detail in U.S. patent application Ser. No. 11/176,598, incorporated by reference herein in its entirety. Further, various materials may be used to fabricate and manufacture sheath catheter segment, rotatable apparatus and orientation platform devices. For example, it is contemplated that in addition to that disclosed above, materials including, but not limited to, stainless steel, copper, aluminum, nickel-titanium alloy (Nitinol), Flexinol® (available from Toki of Japan), titanium, platinum, iridium, tungsten, nickel-chromium, silver, gold, and combinations thereof, may be used to manufacture components such as control elements, control cables, segments, gears, plates, hall units, wires, springs, electrodes, thermocouples, etc. Similarly, non-metallic materials including, but not limited to, polypropylene, polyurethane (Pebax®), nylon, polyethylene, polycarbonate, Delrin®, polyester, Kevlar®, carbon, ceramic, silicone, Kapton® polyimide, Teflon® coating, polytetrafluoroethylene (PTFE), plastic (non-porous or porous), latex, polymer, etc. may be used to make the various parts of a catheter, orientation platform, tool, etc.
• Additionally, certain system components are described as having lumens that are configured for carrying or passage of control elements, control cables, wires, and other catheter instruments. Such lumens may also be used to deliver fluids such as saline, water, carbon dioxide, nitrogen, helium, for example, in a gaseous or liquid state, to the distal tip. Further, some embodiments may be implemented with an open loop or closed loop cooling system wherein a fluid is passed through one or more lumens in the sidewall of the catheter instrument to cool the catheter or a tool at the distal tip.
• Further, embodiments may be utilized with various working instruments including end effectors including, for example, a Kittner dissector, a multi-fire coil tacker, a clip applier, a cautery probe, a shovel cautery instrument, serrated graspers, tethered graspers, helical retraction probe, scalpel, basket capture device, irrigation tool, needle holders, fixation device, transducer, and various other graspers. A number of other catheter type instruments may also be utilized together with certain embodiments including, but not limited to, a mapping catheter, an ablation catheter, an ultrasound catheter, a laser fiber, an illumination fiber, a wire, transmission line, antenna, a dilator, an electrode, a microwave catheter, a cryo-ablation catheter, a balloon catheter, a stent delivery catheter, a fluid/drug delivery tube, a suction tube, an optical fiber, an image capture device, an endoscope, a Foley catheter, Swan-Ganz catheter, fiberscope, etc. Thus, it is contemplated that one or more catheter instruments may be inserted through one or more lumens of a flexible catheter instrument, flexible sheath instrument, or any catheter instrument to reach a surgical site at the distal tip. Similarly, it is contemplated that one or more catheter instruments may be passed through. an orientation platform to a region of interest.
• While multiple embodiments and variations of the many aspects of the present disclosure have been disclosed and described herein, such disclosure is provided for purposes of illustration only. Many combinations and permutations of the disclosed system are useful in minimally invasive medical intervention and diagnosis, and the system is configured to be flexible. The foregoing illustrated and described embodiments of the present disclosure are susceptible to various modifications and alternative forms, and it should be understood that the present disclosure generally, as well as the specific embodiments described herein, are not limited to the particular forms or methods disclosed, but also cover all modifications, equivalents and alternatives. Further, the various features and aspects of the illustrated embodiments may be incorporated into other embodiments, even if no so described herein, as will be apparent to those skilled in the art.

Claims (20)

What is claimed is:

1. An instrument system, comprising:

an elongate body;

an optical fiber operatively coupled to the elongate body and having a plurality of strain sensors provided on the optical fiber; and

a controller operatively coupled to the optical fiber and adapted to:

obtain signals from one of the plurality of strain sensors more frequently than from another of the plurality of strain sensors; and

determine a position of the elongate body based on the obtained signals from the one of the plurality of strain sensors.

2. The instrument system ofclaim 1, wherein the optical fiber comprises a proximal portion. and a distal portion, and wherein the one of the plurality of strain sensors is located on the distal portion and the another of the plurality of strain sensors is located on the proximal portion.

3. The instrument system ofclaim 1, wherein the controller is adapted to obtain the signals by selecting, based on movement of the elongate body, the one of the plurality of strain sensors to be sampled more frequently.

4. The instrument system ofclaim 1, wherein the optical fiber comprises a first proximal portion and a second proximal portion, wherein the second proximal portion is more proximal than the first proximal portion, and wherein the controller is adapted to select, based on an increase in signal amplitude of signals from the first proximal portion relative to signals from the second proximal portion, the first proximal portion to be sampled more frequently.

5. The instrument system ofclaim 1, wherein the plurality of strain sensors comprise a plurality of axially-spaced Bragg gratings.

6. The instrument system ofclaim 5, wherein the plurality of axially-spaced Bragg gratings are substantially continuous along the optical fiber.

7. An instrument system, comprising:

an elongate body;

an optical fiber operatively coupled to the elongate body and having a plurality of strain sensors provided on the optical fiber; and

a controller operatively coupled to the optical fiber and adapted to:

select a reference strain sensor from among the plurality of strain sensors;

receive signals from the plurality of optical fibers; and

determine, based on the signals received from the plurality of strain sensors, a position of the elongate body relative to a position of reference strain sensor.

8. The instrument system ofclaim 7, wherein one of the plurality of strain sensors is most proximal to the controller, and wherein the selected reference strain sensor is not the one of the plurality of strain sensors.

9. The instrument system ofclaim 8, wherein the selected reference strain sensor is adjacent to the one of the plurality of strain sensors.

10. The instrument system ofclaim 7, wherein the reference strain sensor is a first strain sensor, and wherein the controller is adapted to select a second reference strain sensor from among the plurality of strain sensors.

11. The instrument system ofclaim 10, wherein the controller is adapted to determine a position of the first strain sensor relative to a position of the second reference strain sensor.

12. The instrument system ofclaim 7, further comprising a localization sensor operatively coupled to the elongate body, wherein the controller is adapted to determine a position of the reference strain sensor relative to a position of the localization sensor.

13. The instrument system ofclaim 7, wherein the instrument system is adapted to prevent the reference strain sensor from moving.

14. The instrument system ofclaim 7, wherein the plurality of strain sensors comprises a plurality of Bragg gratings that are substantially continuous or overlapping.

15. An instrument system, comprising:

an elongate body;

an optical fiber operatively coupled to the elongate body and having a plurality strain sensors provided on the optical fiber; and

a controller operatively coupled to the optical fiber and adapted to:

select a measurement strain sensor from among the plurality of strain sensors;

receive a signal from the measurement strain sensor; and

determine, based on the signal, a position of a portion of the elongate body at which the measurement strain sensor is located.

16. The instrument system ofclaim 15, wherein the measurement strain sensor comprises a Braga grating, and wherein the controller is configured to receive the signal by measuring only a portion of the Bragg grating, Wherein a length of the portion of the Braga grating is less than a length of the Bragg grating.

17. The instrument system ofclaim 16, wherein the plurality of Bragg gratings are overlapping.

18. The instrument system ofclaim 15, wherein the controller is further configured to select a reference strain sensor from among the plurality of strain sensors, and wherein the controller is configured to determine the position of the portion of the elongate body relative to a position of the reference strain sensor.

19. The instrument system ofclaim 18, wherein the selected reference strain sensor is adjacent to the selected measurement strain sensor.

20. The instrument system ofclaim 15, wherein one of the plurality of strain sensors is most proximal to the controller, and wherein the selected measurement strain sensor is not the one of the plurality of strain sensors.

Images