US20050119790A1 - Microwrist system for surgical procedures - Google Patents

Abstract

A medical robotic system with a handle assembly that is used to control a medical instrument. The handle assembly and medical instrument have five degrees of freedom. Five degrees of freedom may provide greater dexterity than medical robotic systems of the prior art with four or less degrees of freedom. Five degrees of freedom reduces the size and complexity of the instrument.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS
• This is a continuation patent application which claims priority from U.S. patent application Ser. No. 10/013,067 filed on Dec. 7, 2001, the full disclosure of which is incorporated herein by reference.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
• NOT APPLICABLE
REFERENCE TO A “SEQUENCE LISTING,” A TABLE, OR A COMPUTER PROGRAM LISTING APPENDIX SUBMITTED ON A COMPACT DISK
• NOT APPLICABLE
BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a handle assembly for a medical robotic system.
• 2. Background Information
• Historically, surgery has been performed by making large incisions in a patient to provide access to the surgical site. There has been developed instruments that allow a surgeon to perform a procedure through small incisions in the patient. The instruments include an endoscope which has a camera that allows the surgeon to view the internal organs of the patient through a small incision. Such procedures are less traumatic to the patient and have shorter recovery times than conventional surgical procedures. Endoscopic instruments have even been used to perform minimally invasive heart surgery. Blockage of a coronary artery may deprive the heart of blood and oxygen required to sustain life. The blockage may be removed with medication or by an angioplasty. For severe blockage, a coronary artery bypass graft (CABG) is performed to bypass the blocked area of the artery. CABG procedures are typically performed by splitting the sternum and pulling open the chest cavity to provide access to the heart. An incision is made in the artery adjacent to the blocked area. The internal mammary artery is then severed and attached to the artery at the point of incision. The internal mammary artery bypasses the blocked area of the artery to again provide a full flow of blood to the heart. Splitting the sternum and opening the chest cavity can create a tremendous trauma to the patient.
• COMPUTERMOTIONof Goleta, Calif. provides a system under the trademark ZEUS® that allows a surgeon to perform a minimally invasive surgery, including CABG procedures. The procedure is performed with instruments that are inserted through small incisions in the patient's chest. The instruments are controlled by robotic arms. Movement of the robotic arms and actuation of instrument end effectors are controlled by the surgeon through a pair of handles and a foot pedal that are coupled to an electronic controller. Alternatively, the surgeon can control the movement of an endoscope used to view the internal organs of the patient through voice commands. Additionally, the cracked sternum prolongs the recovery period of the patient.
• The incisions create pivot points for the medical instruments. The pivot points constrain movement of the instruments within the patient to four degrees of freedom; translation, pan, tilt and rotation of the instrument shaft. Additionally, the pivot point may cause a reverse movement of the instrument. For example, leftward movement of the system input handle may actually cause a rightward movement of the instrument. The surgeon must compensate for such constraints, thereby increasing the difficulty of using the system for performing a medical procedure.
• It would be desirable to provide a robotic handle that gives the user the sensation of controlling the tip of the instrument. It would also be desirable to generally improve the ergonomics of medical robotic master handles.
• There have been developed medical robotic systems that create six degrees of freedom for the surgical instruments. Six degrees of freedom requires relatively complex mechanism that increases the size and cost of the system. It would be desirable to provide an effective medical robotic system that would only require five degrees of freedom.
BRIEF SUMMARY OF THE INVENTION
• A master robotic handle assembly that has only five degrees of freedom. The master handle assembly is used to move a robotically controlled surgical instrument.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a top view of an illustration of a robotic system;
• FIG. 2 is a perspective view of a surgeon control area of the robotic system;
• FIG. 3 is a perspective view of a handle assembly of the robotic system used to control a medical instrument;
• FIG. 4 is an enlarged perspective view of a wrist assembly of the robotic system controlled by a user's hand;
• FIG. 5 is a sectional perspective view of the handle/wrist assembly.
DETAILED DESCRIPTION OF THE INVENTION
• Disclosed is a medical robotic system with a handle assembly that is used to control a medical instrument. The handle assembly and medical instrument have five degrees of freedom. Five degrees of freedom may provide greater dexterity than medical robotic systems of the prior art with four or less degrees of freedom. Five degrees of freedom reduces the size and complexity of the instrument and the overall robotic system.
• Referring to the drawings more particularly by reference numbers,FIG. 1 shows arobotic system10. Thesystem10 may include a plurality ofrobotic arms12 located adjacent to a table14. Two of therobotic arms12 may control the movement of corresponding medical instruments (not shown). The thirdrobotic arm12 may control the movement of an endoscope (not shown). The robotically controlled instruments and endoscope may be used to perform a minimally invasive medical procedure on a patient lying on the table14.
• Therobotic arms12 and accompanying instruments may be the same or similar to robotic products sold by Computer Motion under the trademarks AESOP® and ZEUS®. Although threerobotic arms12 are shown and described, it is to be understood that thesystem10 may have a different number ofarms12.
• Therobotic arms12 are controlled from a “surgeon”area16. Thesurgeon area16 may be located adjacent to the table14. Alternatively, thesurgeon area16 may be coupled to therobotic arms12 through a telecommunications link to allow a surgeon to have remote input into thesystem10.
• FIG. 2 shows asurgeon area16. Thesurgeon area16 includes a pair ofhandle assemblies18 located adjacent to a surgeon'schair20. The handle'assemblies18 are coupled to acontroller22 that is also coupled to therobotic arms12 and medical instruments. Thecontroller22 may include one or more microprocessors, memory devices, drivers, etc. that convert input information from thehandle assemblies18 into output control signals which move the robotic arms and/or actuate the medical instruments.
• The surgeon'schair20 and handleassemblies18 may be in front of avideo console24. Thevideo console24 may be linked to the endoscope to provide video images of the patient. The surgeon'sarea16 may also include acomputer screen26 coupled to thecontroller22. Thescreen26 may display graphical user interfaces (GUIs) that allow the surgeon to control various functions and parameters of thesystem10.
• Eachhandle assembly18 may include a handle/wrist assembly30. The handle/wrist assembly30 has ahandle32 that is coupled to awrist34. Thewrist34 is connected to aforearm linkage36 that slides along aslide bar38. Theslide bar38 is pivotally connected to an elbow joint40. The elbow joint40 is pivotally connected to a shoulder joint42 that is attached to thecontroller22.
• FIG. 3 shows ahandle assembly18 superimposed with amedical instrument50. Theinstrument50 includes anend effector52 attached to aninstrument shaft54. Theshaft54 extends through acannula56 inserted through an incision of apatient58. The incision defines a pivot point P for themedical instrument50.
• Theshoulder joint42 includes a sensor (not shown) that provides feedback on the movement of the handle about ashoulder axis60. The sensor may be a mechanical encoder, optical encoder, etc. or other device which provides an output signal that corresponds to a position of thehandle32 about theshoulder axis60. The output of the shoulder sensor is provided to thecontroller22. Thecontroller22 performs a series of computations to determine a corresponding movement of themedical instrument50. The computations may include one or more transformation and kinematic equations. Thecontroller22 provides output signals to the correspondingrobotic arm12 to move theinstrument50 about point P as indicated by thearrow62.
• The elbow joint40 includes a sensor (not shown) that provides positional feedback on the position of the assembly about anelbow axis64. Thecontroller22 utilizes the positional feedback to drive the robotic arm and move the instrument in the direction indicated by thearrow66.
• Theforearm linkage36 andslide bar38 create a translator68 that allows linear movement of thelinkage36 along atranslator axis70. Thetranslator axis70 intersects with theaxes60 and64. The translator68 has a sensor (not shown) that provides feedback information that is used to drive the robotic arm and move theinstrument50 in the direction indicated by thearrows72.
• When transforming movement of thehandle32 to movement of theinstrument50 thecontroller22 may equate the intersection of theaxes60,64 and70 to the instrument pivot point P. Equating the intersection of theaxis60,64 and70 with the pivot point P provides a kinematic relationship such that the surgeon “feel” like they are actually moving theinstrument50. Additionally, the length of the forearm linkage and location of the handle are such that the surgeon is provided with the sensation that they are holding and moving the distal end of the instrument. These relationships also improve the ergonomics of the handle assembly and the ease of use of the robotic system as a whole. The transformation and kinematic equations may be similar to the equations used in the AESOP® and ZEUS® products with the signs (+/−) reversed to account for theelbow axis64 being behind the surgeon.
• Thehandle assembly18 has only five degrees of freedom; handle spin, wrist, translator, elbow and shoulder. Having only five degrees of freedom reduces the complexity of thesystem10. Themedical instrument50 thus only needs a wrist with one degree of freedom which reduces the complexity, size and corresponding cost of the instrument. The configuration of the handle assembly allows the surgeon to perform any movement of the instrument with only five degrees of freedom.
• FIGS. 4 and 5 show the wrist/handle assembly30. Thewrist34 includes ajoint shaft74 that is coupled to theforearm linkage36 by aroll bearing76. Theroll bearing76 allows thehandle32 to rotate about aroll axis78. Theroll axis32 may further include asensor80 that provide positional feedback to thecontroller22. Movement of thehandle32 about theroll axis78 may cause a corresponding rotation of theinstrument end effector52 in the direction indicated by thearrows110 inFIG. 3.
• Thehandle32 includes agrasper84 that is coupled to ahandle housing86. Thehousing86 andgrasper84 are preferably shaped as an ellipsoid that allows the user to more easily grasps thehandle32 with their hand. Thehousing86 may have athumb groove88 that receives the user's thumb. Thegrasper84 may have a pair ofgrooves90 and92 to receive the index and middle fingers of the user respectively.
• Thehandle32 can rotate about awrist axis94. Thewrist32 provides a fifth degree of freedom not found in medical robotic systems of the prior art. Thewrist32 may include asensor104 that provides positional feedback for thecontroller22. To improve the ergonomics of the wrist/handle assembly30 thewrist axis94 preferably intersects theroll axis78 at acentroid96 located between thethumb98,index finger100 andmiddle finger102 of the user's hand. It has been found that such a configuration creates a more ergonomically correct feel of thehandle32 and movement of thehandle assembly30.
• Thesensors104 provide positional feedback information to thecontroller22 which is used to spin themedical instrument50 as indicated by thearrows82 inFIG. 3.
• Thegrasper84 can be depressed by user. Thegrasper84 is coupled to asensor112 which provides feedback information to thecontroller22. The feedback information is used by thecontroller22 to actuate theend effector52 shown inFIG. 3. By way of example, depressing thegrasper84 may close theend effector52. Thegrasper84 may include aswitch114 that allows the user to lock the position of thegrasper84 and theend effector52 of the corresponding medical instrument. The lockingswitch114 may be coupled to a ratchet (not shown) that allows thegrasper84 andcorresponding end effector52 to be locked at a number of different positions.
• Thehandle32 may have a plurality ofbuttons116,118 and120 that can be depressed by the user. By way of example,button116 may be used to activate a cutting mode on a cauterizing end effector.Button118 may be used to activate a coagulating medical instrument. Thebutton120 may be used to used to vary different functions of the system.
• While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.

Claims (8)

1. A robotic master handle assembly for manipulation by a user's hand having a centroid located between a thumb, an index finger and a middle finger, the assembly comprising:

a handle having a handle body and a grasper movable relative to the handle body by grasping of the handle with the thumb, index finger, and middle finger of the user's hand;

a wrist body coupled to said handle by a handle joint so as to allow rotation of the handle about a handle-wrist spinning axis;

a wrist joint for coupling the wrist body to a handle linkage, the wrist joint allowing the wrist body and handle to be rotated about a wrist-linkage roll axis, the roll axis intersecting the spinning axis at the centroid of the user's hand.

2. The assembly ofclaim 1, wherein said handle body includes thumb groove, and said grasper includes first and second grooves configured for receiving said index finger and said middle finger of the user's hand.

3. The assembly ofclaim 2, wherein said grasper includes a switch.

4. The assembly ofclaim 3, wherein said handle body includes a plurality of buttons.

5. The assembly ofclaim 2, wherein the handle comprises an ellipsoid configured for grasping by the hand of the user, the centroid being disposed within the ellipsoid when the hand of the user grasps the handle.

6. The assembly ofclaim 1, further comprising the linkage coupled to the wrist body, the linkage comprising:

translator means for allowing lateral translation of said wrist and said handle;

elbow means for allowing rotation of said translator means, said wrist body and said handle about an elbow axis; and

shoulder means for allowing rotation of said elbow means, said translator means, said wrist body and said handle about a shoulder axis.

7. The assembly ofclaim 1, further comprising the linkage coupled to the wrist body, the linkage comprising:

a translator that is coupled to said wrist joint;

an elbow joint coupled to said translator; and

a shoulder joint coupled to said wrist joint.

8. The assembly ofclaim 1, wherein the handle is positionable in only five degrees of freedom.

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