US20070013655A1 - Force feedback devices using fluid braking - Google Patents

Abstract

A haptic feedback device including a fluid viscosity-controlled brake that outputs high forces to the device user at low cost while maintaining inherent safety. An interface device includes a manipulandum physically contacted by the user. A sensor senses a position of the manipulandum and outputs a sensor signal. The interface device also includes a brake including a field-controlled fluid having a viscosity that can be controlled by controlling an electric current in a coil, where a resistive force or drag on the manipulandum is controlled by controlling the fluid's viscosity. The fluid can be an electrorheological fluid controlled by an electric field or a magnetorheological fluid controlled by a magnetic field. In one preferred embodiment, the resistive force is controlled by adjusting a degree of contact of the brake with the manipulandum based on the fluid's viscosity.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of co-pending U.S. patent application Ser. No. 09/547,782, filed Apr. 12, 2000, whereby application Ser. No. 09/547,782 is a continuation-in-part of U.S. patent application Ser. No. 09/028,082, now U.S. Pat. No. 6,486,872, filed Feb. 23, 1998, which is a continuation of U.S. patent application Ser. No. 08/489,068, now U.S. Pat. No. 5,721,566, filed Jun. 9, 1995. Application Ser. No. 09/547,782 is also a continuation-in-part of U.S. patent application Ser. No. 08/965,720, filed Nov. 7, 1997. The application Ser. No. 09/547,782 also claims priority to U.S. Provisional Application No. 60/128,975, filed Apr. 12, 1999.
BACKGROUND
• The present invention relates generally to the interfacing with computer devices by a user, and more particularly to devices used to provide input to computer systems and which provide force feedback to the user.
• Humans interface with electronic devices in a variety of applications, and there is a constant need for a more natural, easy-to-use, and versatile interface device. One of those applications includes interacting directly with computer-generated environments. Interface devices are used extensively with computer systems in the implementation of computer-controlled games, simulations, and other applications very popular with the mass market of home consumers. In a typical implementation, a computer system such as a personal computer, home video game console, portable computer, stand-up arcade machine, etc., displays a graphical environment to a user on a display device. Users can interact with the displayed environment by inputting commands or data from the interface device. Popular interface devices include joysticks, “gamepad” button controllers, mice, trackballs, styluses, tablets, steering wheels, pressure spheres, foot or hand pedals, or the like, that are connected to the computer system controlling the displayed environment. The computer updates the environment in response to input signals from the interface device based on the user's manipulation of a moved manipulandum such as a joystick handle, wheel, or mouse. The computer provides visual feedback to the user using the display screen.
• In some interface devices, tactile and/or kinesthetic feedback is also provided to the user, more generally known as “haptic feedback” herein. These types of interface devices can provide physical sensations to the user manipulating the physical object of the interface device. Typically, motors or other actuators of the interface device are coupled to the manipulandum and are connected to the controlling computer system. The computer system receives sensor signals from the interface device and sends appropriate force feedback control signals to the actuators in conjunction with host events. The actuators then provide forces on the manipulandum. The computer system can thus convey physical sensations to the user in conjunction with other visual and auditory feedback as the user is contacting the manipulandum. Commercially available force feedback devices include the Wingman Force joystick and Wingman Formula Force steering wheel from Logitech, Inc., and the Sidewinder Force Feedback Pro joystick from Microsoft Corporation.
• Many types of actuators for generating computer-controlled forces are known, including DC and stepper motors, voice coils, hydraulic actuators, and pneumatic actuators. Some devices are active, such as motors, which means that the device provides an active force that has the ability to move an object or push back on the user. Other actuators are passive, such as brakes, which provide a resistance to motion generated by another source (such as the user) and cannot generate forces on their own. An advantage of active devices is their ability to simulate all kinds of force sensations. However, disadvantages of active actuators include instability: the actuators can settle into a feedback loop in which oscillating forces are output on the manipulandum, for example. Other disadvantages of active actuators include a high cost, and large size and weight. Passive actuators, on the other hand, while not able to output all the types of force sensations of active actuators, can provide relatively high magnitude forces and are inherently stable and safe, and are typically of low cost and weight. However, standard passive actuators can still be expensive for lower-cost devices and can still add significant weight to an interface device.
SUMMARY
• The present invention provides a number of embodiments for a force feedback interface device that uses an efficient and small-sized fluid viscosity-controlled brake that outputs high forces at low cost while maintaining inherent safety.
• More particularly, an interface device of the present invention is manipulated by a user and provides input signals to a host computer. The device includes a manipulandum physically contacted by the user and moveable in at least one degree of freedom. A sensor, such as a rotary optical encoder or analog potentiometer, senses a position of the manipulandum in the degree of freedom and outputs a sensor signal, where a representation of the sensor signal is provided to the host computer. The interface device also includes a fluid-controlled brake including a fluid having a viscosity that can be controlled by controlling an electric current, wherein a resistive force or drag on the manipulandum is controlled by controlling a viscosity of the fluid. In one preferred embodiment, the resistive force is controlled by adjusting a degree of contact of the brake with the manipulandum based on the fluid's viscosity. The fluid can be a magnetorheological fluid having a viscosity controlled by a magnetic field provided by current in a coil, or an electorheological fluid having a viscosity controlled by an electric field.
• Several embodiments of the invention can be implemented. For example, a magnetorheological fluid can be suspended in a sponge, such as available from Lord Corporation, which includes an absorbent matrix material, allowing different resistances to be controlled. The sponge can contact a surface that is coupled to the manipulandum, where the surface can be part of a disk or plate. Other embodiments may provide pistons in the fluid. The manipulandum can be moved in rotary or linear degrees of freedom such that the brake can be a rotary or linear brake. The brake can also include a U-shaped member, where an element is coupled to a prong of the U-shaped member and the coil is wound about a central portion of the U-shaped member. Multiple sponges or other such elements can be provided for increased resistive control.
• The host computer preferably runs a graphical simulation or game that is influenced by the movement of the manipulandum by the user. In one embodiment, the simulation portrays a fishing activity, and the manipulandum includes a crank arm of a fishing reel, the fishing reel coupled to at least a portion of a fishing rod. Different resistances on the crank arm can simulate the catching of fish. In a different embodiment, the manipulandum includes a pedal assembly of a stationary bicycle device, where the user interacts with the computer simulation by pedaling and steering the bicycle device and resistance can be output on pedal motion to simulate riding the bicycle up and down inclines. In yet other embodiments, the manipulandum includes a rotary knob for adjusting settings of an electronic device, or includes a cylinder that can be moved in a rotary and translatory degrees of freedom for controlling a cursor. Some embodiments may further include an actuator that outputs a vibrotactile sensation on a housing of the interface device.
• The present invention provides compact, low-cost, and light weight embodiments for interface devices providing braking forces to an interface device. The controlled viscosity brake used in the present invention provides high-magnitude braking forces and is well-suited to small, inexpensive haptic feedback devices, allowing the interface device of the present invention to be used in mass-produced consumer devices.
• These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following specification of the invention and a study of the several figures of the drawing.
BRIEF DESCRIPTION OF THE DRAWINGS
• In the drawings:
• FIG. 1 is a perspective view of one embodiment of an interface device of the present invention;
• FIG. 2 is a perspective view of a mechanical system suitable for use with the interface device ofFIG. 1;
• FIG. 3 is a perspective view of a second embodiment of an interface device of the present invention;
• FIG. 4ais a perspective view of a third embodiment of an interface device of the present invention;
• FIG. 4bis a perspective view of the third embodiment ofFIG. 4aincluding an additional sensor;
• FIG. 5 is a perspective view of a fourth embodiment of an interface device of the present invention; and
• FIG. 6 is a block diagram illustrating the interface device and host computer for use with the present invention.
DETAILED DESCRIPTION
• FIG. 1 is a perspective view of a first embodiment of a forcefeedback interface device10 of the present invention, in which a fishing game or simulator is implemented. Thedevice10 is used for interfacing a user with a computer generated environment implemented by ahost computer12.
• Interface device10 of the described embodiment is in the form of a fishing rod and reel, of similar shape and size to rods and reels used by fisherman, and includes areel unit14 and arod16.Reel unit14 of theinterface device10 can be shaped and sized similarly to a reel used on a standard fishing rod, and includes areel housing16 and a reel crankarm18.Reel housing16 encloses mechanisms for reading the position of the reel crank18 and providing haptic feedback on the reel crank18, as described in greater detail below with respect toFIG. 2. Reel crankarm18 can be rotated by the user in a rotary degree of freedom similar to a crank arm on a standard fishing reel. A sensor signal is preferably provided to thehost computer14 on a bus24 indicative of the position (and/or velocity, acceleration) of thecrank arm20 in its degree of freedom.
• Rod16 is a generally cylindrically-shaped member that includes agrip22 on one end and which is coupled to thereel unit14.Rod16 can be coupled to thereel unit14 with standard couplings similar to those used on standard fishing rods, or by some coupling specific to thedevice10. Therod16 is preferably not a full-length fishing rod due to the unwieldiness of such a long device, but is instead a portion of a full-length rod (some embodiments can include a full length rod). Weights can be distributed in the rod as necessary to simulate the weight and motion of a full length rod. In other embodiments, differently-shapedreel units14,rods16, crankarm20, and other components can be used. In addition, therod16 can be made to pass through apertures in thehousing18 of thereel unit14 in some embodiments. Furthermore, some embodiments can include one or more buttons or similar controls (dials, knobs, direction pads, sliders, trackballs, etc.) provided on the surface ofreel unit14 and/orrod16 that can provide input signals to thehost computer14.
• Additional sensors and actuators can be included in thedevice10 in other embodiments. For example, one or more gyroscopes, accelerometers, visual sensors, or other types of sensors well known to those skilled in the art can be provided to detect the angle and/or motion of theentire device10 as it is being moved around by the user in a fishing simulation. With such sensors, thehost computer12 can track the position and orientation of thedevice10 with respect to a ground, and can orient a virtual fishing rod and/or hook in response to the determined position and orientation. In addition, other actuators can be provided to output other types of force sensations to the user in addition to the haptic feedback output on thecrank arm20. For example, an actuator such as a motor can be provided to drive an inertial mass and output inertial forces on thedevice10. The inertial mass can be oscillated or rotated to provide oscillations, pulses, or textures on therod16 andreel unit14 and therefore to the user. In some embodiments, an eccentric mass can be rotated by a rotary actuator to provide forces. Some methods of controlling such an actuator for providing different force sensations is described in copending U.S. provisional application No. 60/156,354, incorporated herein by reference. In other embodiments, a mass can be moved linearly in a particular direction by a linear or rotary actuator to provide a vibrotactile sensation. An example of such an actuator is described in copending provisional application No. 60/172,953, incorporated herein by references. Such forces can be used to provide tugs and jolts from a simulated fish caught within a game or simulation. For example, a pulse or vibration in the up-down direction might simulate the fishing pole being bent and tugged by a fish in that direction.
• Interface device10 is coupled tohost computer12 by a bus24, which can be any of several types of communication media. For example, a serial interface bus, parallel interface bus, or wireless communication link (e.g., infrared, radio frequency, etc.) can be used. Specific implementations can include Universal Serial Bus (USB), IEEE 1394 (Firewire), RS-232, or other standards.
• Host computer12 is preferably a personal computer, workstation, video game console, or other computing or electronic device. Personal computers, such as an IBM-compatible or Macintosh personal computer, or a workstation, such as a SUN or Silicon Graphics workstation, can be used. Alternatively, one of a variety of home video game systems, such as systems available from Nintendo, Sega, or Sony, a television “set top box” or a “network computer”, etc. can be used. Or, thehost12 anddevice10 can be included in a single housing in an arcade game machine, portable computer, or other device.Host computer system12 preferably implements a host application program with which a user is interacting via peripherals andinterface device10. For example, the host application program can be a video or computer game, medical simulation, scientific analysis program, operating system, graphical user interface, or other application program.
• The host application preferably displays graphical images of the environment on a display device included with the host computer, such as adisplay screen30, a television, 3D display goggles, LCD display, etc. The software and environment running on the host computer.12 may be of a wide variety. For example, the host application program can be a video game, simulation, graphical user interface (GUI), Web page or browser that implements HTML or VRML instructions, scientific analysis program, virtual reality training program or application, or other application program that utilizes input from theinterface device10 and outputs force feedback commands to thedevice10. For example, many game application programs include force feedback functionality and may communicate with the forcefeedback interface device10 using standard force feedback protocols/drivers such as the Immersion API available from Immersion Corporation of San Jose, Calif. Herein,computer12 may be referred as displaying “graphical objects” or “entities.” These objects are not physical objects, but are logical software unit collections of data and/or procedures that may be displayed as images bycomputer12 ondisplay screen34, as is well known to those skilled in the art. A displayed cursor or a simulated view of a controlled character might be considered a graphical object.
• In operation, the controls ofinterface device10 are manipulated by the user, which indicates to the computer how to update the implemented application program(s). An electronic interface can be included inhousing18 ofdevice10 and can couple thedevice10 to thecomputer12. Thehost computer12 receives the input from the interface device and updates an application program in response to the input. For example, a game presents a graphical environment in which the user controls one or more graphical objects or entities using thedevice10 and other controls such as buttons. In force feedback embodiments, the host computer provides force feedback commands and data to thedevice10 to cause force feedback to be output on crankarm20 and/or other controls.
• In the described embodiment, the host application is preferably a fishing game or simulation in which the user controls a fishing character or a hook that is directed out into water and used to reel in fish caught within the game or simulation. The user grasps thedevice10 with one hand atgrip22 and the other hand grasping the rotational handle of thecrank arm20. The force feedback output on crankarm20 allows the simulation of a fish caught on a fishing line, where thecrank arm20 is more difficult to move due to the fish tugging at the other end of the simulated fishing line.
• FIG. 2 is a perspective view of amechanism50 for use with the fishing reel embodiment of theinterface device10 of the present invention.Mechanism50 is coupled to thecrank arm20 and includes asensor52, adisk54, and abraking mechanism56.
• Sensor52 is coupled to thecrank arm20 by a rotary shaft53 in the embodiment shown inFIG. 2.Sensor52 can be a digital optical encoder, analog potentiometer, or other sensing device. Thesensor52 detects the position of thecrank arm20 in its rotational degree of freedom (about axis A) and relays signals tohost computer12 or to a different controller that include information indicative of the sensed position of the crank arm.Sensor52 can be an absolute or relative sensor. In other embodiments, various other types of sensors can be used, including non-contact sensors such as optical sensors having an emitter and a detector, magnetic sensors, etc. Velocity and/or acceleration sensors may also be used. When a user rotates thecrank arm20, the computer can track the motion and uses that motion to simulate the fishing rod action, such as the position in a graphical environment of a simulated hook on a simulated fishing line.
• Forces are applied to thecrank arm20 using thecomponents including disk54 andbraking mechanism56.Disk54 is made of a magnetically permeable material such as a suitable metal plate or the like having a engagement surface and is rigidly coupled to thecrank arm20 at approximately the center of the disk so that thedisk54 rotates about axis A as the crank arm is rotated.Braking mechanism56 includes a U-shaped support that is oriented such that thedisk54 may be rotated between the prongs of the U shaped support. Thedisk54 and the U-shaped support are made of a material that can provide a flux path for a magnetic field produced by the braking mechanism, such as iron.
• In the embodiment shown, a magnetorheological “sponge”62 is coupled to each of the two prongs of theU-shaped member60 such that each sponge contacts the surface of thedisk54. A magnetorheological sponge allows magnetorheological fluid to be used in a braking device or method. Magnetorheological fluid is a fluid that has a viscosity that can be changed by a magnetic field. By applying the magnetic field at different strengths, different viscosities are produced. Eachsponge62 includes an absorbent matrix material which holds the magnetorheological fluid. When a magnetic field is applied to the sponge, the magnetorheological fluid suspended in the sponge changes its viscosity and thedisk54 contacting the sponge encounters greater or less resistance, depending on whether viscosity has increased or decreased, respectively. A magnetorheological sponge suitable for use with the present invention is available from Lord Corporation of Cary, N.C. Other elements besides sponges can also be used which can suspend a fluid and/or provide varying degrees of resistance on a surface (such as the surface of disk54) based on the viscosity of the fluid.
• Acoil64 of wire is wound at the base portion of theU-shaped support60. When an electric current is flowed through thecoil64, a magnetic field is generated; the magnetic field extends through thesponges62 and changes the viscosity of the magnetorheological fluid suspended in the sponges. This creates more drag between thedisk54 and thesponges62, thus creating more force resistance in the rotary degree of freedom of thedisk54. The resistance can be increased or decreased by adjusting the current in the coil. In some embodiments, a single magnetorheological sponge can be provided on only one side of thesupport60 to contact thedisk54 on only one of its sides. In still other embodiments, other-shaped supports can be used and other flat members instead of a circular-shaped disk.
• Magnetorheological braking devices achieve high force for low component cost. In addition, these devices can be very low power, thereby allowing for further reduction in system cost. In addition, these devices, like all braking devices, are inherently stable, thereby allowing for reduced cost on control electronics/processor electronics. In addition, these devices are light weight.
• In other embodiments, a linear magnetorheological brake can be implemented by providing a plate similar to thedisk54 and coupling a magnetorheological sponge to a linearly-moving member. The sponge is put in contact with the plate and resistance on the linearly-moving member can be controlled similarly as described above for the rotary brake. In still other embodiments, magnetorheological fluid can be forced through valves or other channels similar to hydraulic devices and its viscosity controlled to resist motion of a piston or other member through the fluid in varying degrees. Some embodiments using valves and pistons that can be used with the present invention are described in U.S. Pat. No. 5,721,566, which is incorporated herein by reference.
• In other embodiments, other types of fluids having a controllable viscosity can be used. For example, an electrorheological fluid can be used instead of the magnetorheological fluid discussed above, where the fluid's viscosity is controlled with an electric field instead of a magnetic field. The electric field can be produced between parallel plates having a voltage potential, similar to a capacitor used in electronic circuits. A sponge or other element that is positioned in the electric field and frictionally engages a surface can include an eletrorheological fluid and control its degree of contact with the surface, similarly to the magnetorheological sponge described above. Some other embodiments of a fluid-controlled brake using an electrorheological fluid are described in U.S. Pat. No. 5,721,566 and can be used in the present invention. For example, thecrank arm20 can be rotatably coupled to a piston in a cylinder including such a fluid, where the resistance on the crank arm is determined by the resistance on the piston moving through the fluid.
• In the intended operation of the fishing embodiment ofFIG. 1, thebraking mechanism56 simulates a drag on the reel of the fishing device when a fish is caught in a computer-implemented fishing simulation or game. When a fish is caught, the computer (or other control processor) can command “drag” upon thecrank arm20 by causing the magnetorheological brake to activate to cause the fluid viscosity to increase. If a small fish is caught, the computer can cause a low voltage to be applied to the brake, thereby applying a small drag force to the crank arm. A large fish can result in a high voltage, to cause a large drag force to be applied to the crank arm. The various movements of the fish can be simulated by varying the drag on the crank arm while the user is rotating it.
• Braking devices typically hold or resist a moveable object in both directions within a degree of freedom. In some devices, there can be a problem simulating walls or obstruction forces with passive actuators such as brakes due to the difficulty of detecting motion in an opposite direction to the obstruction while the object is being held by the brake. However, since a reel crank arm is only rotated in one direction by a user in normal use during fishing, rotation in the opposite direction need not be sensed, and this problem is bypassed. In other embodiments where bi-directional rotation needs to be sensed, a desired amount of play can be introduced between the sensor and the manipulandum to allow sensing of motion during braking forces for a unidirectional obstruction. Embodiments of such desired play are described in U.S. Pat. No. 5,767,839, incorporated herein by reference.
• Furthermore, a local microprocessor (or other local processing device) can be coupled between the host computer and the reel mechanism to locally control braking forces. Embodiments including such a local microprocessor are described below with reference toFIG. 6. Or, a direct host computer control method can be used, where no local microprocessor is used. Preferably, the product runs off a USB or similar communication link. In the ideal embodiment, all power used to drive the magnetorheological brake is drawn from the USB port or similar interface, or can be drawn from batteries on thefishing device10. What is advantageous of this method over using a motor is that the magnetorheological actuator is light weight, low cost, and low power. That means that the fishing rod interface device can be low cost, feels light to the user, and can run off USB power (not needing an additional external power supply).
• One limitation of the magnetorheological braking described above is that it cannot simulate the active feel of a live fish (like the jolt of a catch or the vibration of a fish struggling at the end of the fishing line). To add this capability, a low cost vibrotactile actuator in combination with the brake can be provided on the fishing rod device, as mentioned above. The vibrotactile actuator can be an inertial vibrotactile actuator such as a motor with an eccentric weight or a linear motor with a moving mass. The vibrotactile actuator can be positioned, for example, directly in thehousing18 of thereel unit14. The rod device can be a full fishing rod, or it can be a smaller device, e.g. just the reel portion and grip portion of the rod. Such a system would allow for very large resistance forces on thecrank arm20 and small vibration forces when a fish is caught or a snag is encountered.
• FIG. 3 is a perspective view of a second embodiment of the present invention.Interface device10′ is a bicycle simulation device that can be used to simulate riding a bicycle, similar to a bicycle exercise machine or the like. Astationary frame80 rests on a ground surface and provides a structure of a similar height to a bicycle. Aseat82 is coupled to the frame on which the user sits during operation of thedevice10′.Handlebars84 are rotatably coupled to theframe80 and are grasped by the user's hands during operation of the device and may be rotated to simulate turning the bicycle. Pedal assembly86 is rotatably coupled to theframe80 and supports the user's feet during operation. The pedal assembly86 includespedal arms88 and pedals90, each pedal90 rotatably coupled to an associatedpedal arm88. Thepedal arms88 are preferably rigidly coupled to each other, where the second pedal arm is oriented 180 degrees from the first pedal arm. Thepedal arms88 can be rotated in a rotary degree of freedom by the user's legs and feet. Other embodiments can include other components, such as one or more wheels which are rotated in place by the pedals to provide an authentic feel. Ahost computer12 is coupled to thebicycle device10′ by a bus92 (or by wireless communication) and includes a display device. The host computer can run a graphical simulation or game so that the user of thedevice10′ can interact with the simulation. Other embodiments may include the display device of the host computer12 (or a display device connected to a local microprocessor) provided on thehandlebars84 for easy viewing by the user.
• Bicycle device10′ preferably includes a number of transducers to interface with thehost computer12. A mechanism similar to that shown inFIG. 2 is preferably used to provide drag or resistance on thepedal arms88 ofbicycle simulation device10′. For example, thepedal arm88 can be thecrank arm20 described forFIG. 2.Disk54 can be positioned between thepedal arms88. The other components shown inFIG. 2 can also be included in the bicycle embodiment to provide sensing and drag on the pedals in their rotary degree of freedom. The pedal motion can be sensed at the pedal itself (e.g.,sensor52 can be directly coupled to a shaft of the pedal arms88) or further down in the mechanism chain (e.g., after a mechanical transmission such as a gear drive, belt drive, or capstan drive). Preferably, a magnetorheological fluid device similar to that described with reference toFIG. 2 is used to exert resistance on the pedal arms. The resistance can also be applied after being amplified or reduced by a mechanical transmission system, such as a belt drive, capstan drive, or gear assembly, positioned between the brake and the grip, pedal, or handle.
• To complete the realism of the simulator, other sensors and actuators can be provided for other functions and effects of the bicycle. For example, a sensor coupled to thehandlebars84 preferably detects the position of the handlebars in their rotary degree of freedom. Additional sensors can be used to measure the position of a gear selector and the position of hand brakes (if present) of the bicycle device. Buttons or other extra controls can also be provided in some embodiments, e.g. for use in a video game.
• During operation, the handlebar sensor(s) indicate to the host computer where the user is steering the bicycle within the game or simulation. When the user rotates the pedal arms (similar to rotating crankarm20 about axis A), thehost computer14 can track the motion and uses that motion to simulate the motion of the simulated bicycle in the game or simulated environment. The system also may generate force resistance on the pedals. For example, the drag on the pedals can be increased when the user is peddling up an incline in the simulation to simulate the increased effort required to move the bicycle in such a situation. When the bicycle is moving down a simulated hill, the drag can be decreased. This can be used for realistic video game applications where a user is peddling and watching the course, road, track, etc. go by on the display device.
• When the user steers the bicycle to move up a hill, the computer or processor can command “drag” upon the pedals by causing the magnetorheological brake to activate. A small hill might result in a low voltage on the brake, thereby applying a small drag force. A large hill might result in a high voltage, thereby providing a large drag force. Since the pedal is only rotated in one direction by the user, the typical limitations of force feedback braking related to rapid direction changes of the user manipulatable object are not present. A local processor can be provided between the host computer and the pedal mechanism, or direct computer control can be used as explained above.
• As with the fishing embodiment described above, this embodiment is low cost, achieves very high forces, and is inherently safe. One limitation of the magnetorheological brake is that it cannot realistically simulate the active vibration feel of going over a bump or a rough road. In some embodiments, this vibration can be simulated using a vibrotactile actuator, e.g. the actuator can be coupled to thebicycle seat82 on which the user is sitting. As described above, the vibrotactile actuator can be an inertial vibrotactile actuator such as a motor with an eccentric weight or a linear motor with a linearly-moving mass. Such a complete system would allow for very large forces on the pedals and small vibration forces on the seat.
• A single local processor can be located on the stationary bicycle, its function being to read the sensor that measures pedal motion, read the sensor that measures handle bar angle or motion, read the sensors that indicate choice of gear, and read the sensors that measure the state of the hand brake(s). All of these sensor values can be sent back to the host computer viacommunication bus92. In addition, the local processor can receive commands or data back from the host computer indicating the amount of drag to be applied to the pedals based upon the terrain in the computer-generated environment.
• In some embodiments, the host computer can be networked to other host computers over a network such as a LAN or the Internet, such that a distributed biking simulation can allow players to compete. For example, data about the course layout as well as the terrain characteristics can be downloaded over the Internet, including incline data used by the host computer to control the drag feel. Also, data about road conditions (bumpiness of feel) can be downloaded from the Internet. A server can keep track of the simulated race, allowing players from distant locations to compete and be timed against each other. Each local processor and/or host application program can have a unique ID number that is transmitted to the host and then back to the server so that every simulated bike in the race can be uniquely identified. By this method, hundred or thousands of racers can compete at once upon the same course while feeling the same terrain. To allow players to compete for cash prices without worry that a competitor has disabled the drag function on their stationary bike or has doctored the pedaling means in some way, the local processor and/or software can also report a self diagnostic status signal to the host which gets relayed to the server, indicating normal functioning (or no tampering).
• FIG. 4ais a perspective view of amechanism100 similar to themechanism50 ofFIG. 2.Mechanism100 can be used to provide haptic feedback to a knob or other rotational user object.Sensor52,disk54, andbrake assembly56 all preferably operate similarly as described above with reference toFIG. 2. Aknob102 is rigidly coupled to ashaft104 which is rigidly coupled to the shaft of therotational sensor52. The user may rotate theknob102 using his or her hand or fingers. This rotation is sensed bysensor52 and relayed to a processor orhost computer12, and force feedback can be output in the rotational degree of freedom of the knob about axis B as controlled by a processor and/orhost computer12.
• The force feedback knob controller using a magnetorheological brake is inherently stable, allowing for controllable damping, controllable hard stops, and controllable detents in the rotational degree of freedom of the knob. For example, hard stops can be programmed at desired locations in the range of travel of the knob using the magnetorheological brake, which can provide higher obstruction forces than many active actuators. Detents can be set at desired positions; a detent can be implemented by outputting a high resistance for a short time or for a short range of travel of the knob, giving the user a sensation of a jolt or pulse at a particular position. Damping can provide a desired resistance to rotational motion and can make selection of a value or positioning of a cursor easier for the user.
• The knob can be provided on a variety of computer devices or interface devices, such as a laptop computer, a consumer electronics device such as a stereo or television, on a handheld remote control, on the dashboard of a car, etc. Theknob102 ofFIG. 4acan be a roller wheel on a mouse, e.g. a wheel positioned at the front center position of a mouse that the user can rotate to scroll documents, make selections, etc. Such wheels typically have a frictional circumferential surface to allow the user a good grip on the wheel. Force feedback can be applied to the mouse wheel to enhance such wheel rotation. Software control and force feedback implementations for knobs and mouse wheels is described in greater detail in copending patent applications Ser. No. 09/049,155, filed Mar. 26, 1998, and Ser. No. 09/179,382, filed Oct. 26, 1998, both incorporated herein by reference. The magnetorheological fluid brake is ideal for hand-held remote controls and other space-limited applications because of low power consumption and light weight, compact components. In other embodiments, linear knobs (sliders) can be provided with a linear magnetorheological brake.
• One space-limited application for use with theknob102 is a selection knob for a laptop computer to provide similar functionality to a standard mouse wheel, and additional functionality if desired. For example, a knob having a rotational axis extending perpendicularly to the laptop's top surface can be placed on the side of the laptop in easy access to user's fingers. The knob can be rotated to scroll documents, move a cursor across the screen or through a list of objects, icons, or selections, etc. Preferably, the knob can be pressed in a direction perpendicular (transverse) to the axis of rotation to provide a selection function, e.g. to select an item, icon, or link at which the cursor is currently pointing. The knob preferably is spring-loaded to rest at a normal operating position, and can be pushed in to select a mechanical switch, where the knob returns to the operating position when the user removes pressure in the pushing direction. One such knob is provided in the Vaio XG19 laptop computer from Sony Corp.
• FIG. 4billustrates one example of the present invention including the knob described above provided with a fluid-controlled brake. The knob can be sensed and actuated in its rotary degree of freedom similar to the embodiment ofFIG. 4a. In addition, the knob,shaft104, anddisc54 can be moved in a transverse direction. Such motion can be implemented in many different ways. For example, two grounded supports106 on either side of theknob102 can be provided. One of the supports106aincludes aslot108 that is larger than the size of the shaft and allows theshaft104 andknob102 to move or pivot within the slot108 (the hole in the other support106bcan include a slightly larger hole to allow the pivoting motion). A mechanical spring (not shown) can be used to provide the spring bias on the knob and shaft toward an origin position. The user can thus move the knob in the transverse direction ofarrow110. A mechanical switch112 (or other type of sensor: optical, magnetic, etc.) can be placed in the path of thedisc54 and is contacted by the edge of thedisc54 when theknob102 is pushed in thetransverse direction110 by the user. Theswitch112 thus detects the motion and outputs an appropriate signal to a processor or host computer, indicating the user has pushed theknob102. Theswitch112 can alternatively be placed at a different position around thedisc54 corresponding to a different path of transverse motion of thedisc54. Theswitch112 may also detect the motion of the shaft or other component of the device.
• In other embodiments, the transverse motion can be implemented in other ways. For example, a flex joint can be used to allow theshaft104 pivot about one end of the shaft. Or, theshaft104 can be placed in a slot in a grounded member that allows the motion in the desired transverse direction. Other mechanisms currently used in rotatable wheels for mice can also be used. In still other embodiments, the transverse motion of theknob110 can be actuated by an actuator so that the feel of the push of theknob102 can be made to feel differently as controlled by a microprocessor or other controller. This transverse actuator is preferably separate from thefluid brake56, e.g. a linear actuator can be coupled between theshaft104 and a grounded surface. In other embodiments, theknob102 can be pushed in a direction parallel to the axis B of rotation of the knob. Some examples of such an embodiment are disclosed in copending patent application Ser. No. 09/179,382, filed Oct. 26, 1998.
• FIG. 5 is a perspective view of anotherembodiment120 of an interface device of the present invention including a magnetorheological brake.Embodiment120 includes a two-degree of freedom cylindrical controller that can be used to provide input control signals to a computer or other electronic device, e.g. to control the movement of a cursor in a graphical user interface displayed by ahost computer12. Acylinder122 may be rotated about an axis C and translated parallel to the axis C by the user. The outer surface of thecylinder122 can include annular and longitudinal grooves124 which intersect each other. Two pinions126 positioned at right angles with respect to each other mesh with the grooves124 so that when the cylinder is rotated, one pinion126arotates, and when the cylinder is translated, the other pinion126brotates. Ametal disk128 is connected to each pinion126 by arotating shaft130, and anmagnetorheological brake132 as described in detail inFIG. 2 provides braking resistance to the rotation of thedisk128, thereby allowing onebrake132 to provide braking resistance to the rotation of thecylinder122 and theother brake132 to independently provide braking resistance to the translation of thecylinder122. Additional cylinder control device embodiments which can be used with the magnetorheological brake are described in greater detail in U.S. Pat. Nos. 5,235,868, 4,823,634, 4,712,101, and 4,724,715 and copending patent application Ser. No. 09/291,582, entitled, “Multiple-cylinder Control Device for Computers and Other Electronic Apparatus”, filed concurrently herewith, all of which are incorporated herein by reference.
• The magnetorheological fluid brakes allow for controllable drag during cursor control tasks. For example, two magnetorheological fluid sponge controllers can be used for the cylinder, one for the rotary axis and one for the linear axis. Alternatively, the rotary axis of the cylinder can use a rotary metal disk, and the linear axis of the cylinder can use a linear sliding metal member in place of the rotary disk, where the magnetorheological brake contacts a sponge with the linearly-moving surface of the metal member.Host computer12 preferably controls the braking resistance, and a device microprocessor can also be used local to the device in addition to the host computer as described above.
• Each axis of the cylinder can be controlled independently to control drag related to cursor motion in x and y independently. For example, a user interacting with a pull-down menu can be provided with resistance sensations when a controlled cursor in a graphical user interface moves between menu elements when using a cylinder controller fitted with a magnetorheological fluid brake. Drag can be momentarily output for other cursor interactions such as moving over a window border or window interior or moving over an icon. Drag can be output continuously when moving in force “grooves” to guide the cursor to particular areas or graphical objects displayed on the screen of the host computer. This is ideal for laptop computers because of the low power consumption and low size and weight of the magnetorheological fluid brakes. Some GUI force feedback interactions are described in copending patent application Ser. No. 08/571,606, incorporated herein by reference.
• FIG. 6 is a block diagram illustrating ahaptic feedback device10 andhost computer14 suitable for use with the present invention.Interface device10 can be any of the embodiments described above. A system similar to that ofFIG. 6 is described in detail in U.S. Pat. No. 5,734,373 which is incorporated herein by reference in its entirety.
• As explained with reference toFIG. 1,host computer12 is preferably a personal computer, video game console, workstation, or other computing or display device.Host computer12 commonly includes a host microprocessor202, aclock204, adisplay device30, and an audio output device206. Host microprocessor202 can include a variety of available microprocessors from Intel, AMD, Motorola, or other manufacturers. Microprocessor202 can be single microprocessor chip, or can include multiple primary and/or co-processors and preferably retrieves and stores instructions and other necessary data from random access memory (RAM) and read-only memory (ROM) as is well known to those skilled in the art.Host computer12 can receive sensor data or a sensor signal viabus208 from sensors ofdevice10 and other information. Microprocessor202 can receive data frombus208 using I/O electronics, and can use the I/O electronics to control other peripheral devices.Host computer system12 can also output commands to interfacedevice10 viabus208 to cause haptic feedback.
• Clock204 can be a standard clock crystal or equivalent component used byhost computer12 to provide timing to electrical signals used by host microprocessor202 and other components of thecomputer12 and can be used to provide timing information that may be necessary in determining force or position values.Display device30 is described with reference toFIG. 1. Audio output device206, such as speakers, can be coupled to host microprocessor202 via amplifiers, filters, and other circuitry well known to those skilled in the art. Other types of peripherals can also be coupled to host processor202, such as storage devices (hard disk drive, CD ROM drive, floppy disk drive, etc.), printers, and other input and output devices.
• Interface device10 is coupled tohost computer12 bybi-directional bus208, which sends signals in either direction betweenhost computer12 and theinterface device10.Bus208 can be a serial interface bus, such as USB, RS-232, or Firewire (IEEE 1394), providing data according to a serial communication protocol, a parallel bus using a parallel protocol, or other types of buses. An interface port ofhost computer12, such as a USB or RS232 serial interface port, can connectbus208 tohost computer12.
• Interface device10 can include alocal microprocessor220,local clock222,local memory224,sensor interface226, andactuator interface228.Device10 may also include additional electronic components for communicating via standard protocols onbus208.
• Local microprocessor220 preferably coupled tobus208 and is considered “local” todevice10, where “local” herein refers toprocessor220 being a separate microprocessor from any processors202 inhost computer12. “Local” also preferably refers toprocessor220 being dedicated to haptic feedback and sensor I/O of thedevice10, and being closely coupled to sensors and actuators of thedevice10, such as within a housing of thedevice10.Microprocessor220 can be provided with software instructions to wait for commands or requests fromcomputer host12, parse/decode the command or request, and handle/control input and output signals according to the command or request. In addition,processor220 can operate independently ofhost computer12 by reading sensor signals and calculating appropriate forces from those sensor signals, time signals, and force processes selected in accordance with a host command, and outputting appropriate control signals to the actuators. Suitable microprocessors for use aslocal microprocessor220 include the Immersion Touchsense Processor from Immersion Corporation, the 8×930AX by Intel Corp., the MC68HC711E9 by Motorola, or the PIC16C74 by Microchip, for example.Microprocessor220 can include one microprocessor chip, or multiple processors and/or co-processor chips. In other embodiments,microprocessor220 can include digital signal processor (DSP) functionality, or control logic components or a hardware state machine can be used instead of a microprocessor.
• For example, in one host-controlled embodiment that utilizesmicroprocessor220,host computer12 can provide low-level force commands overbus208, whichmicroprocessor220 directly transmits to the actuators. In a different local control embodiment,host computer12 provides high level supervisory commands tomicroprocessor220 overbus208, andmicroprocessor220 manages low level force control loops to sensors and actuators in accordance with the high level commands and independently of thehost computer12. In the local control embodiment, themicroprocessor220 can process sensor signals to determine appropriate output actuator signals by following the instructions of a “force process” that may be stored inlocal memory224 and includes calculation instructions, conditions, formulas, force magnitudes, or other data. The force process can command distinct force sensations, such as vibrations, textures, jolts, or even simulated interactions between displayed objects. The host can send thelocal processor220 force sensation parameters to store in local memory, or can clear other force sensations to load new force sensations in memory.
• Alocal clock222 can be coupled to themicroprocessor220 to provide timing data, similar tosystem clock204 ofhost computer12; the timing data might be required, for example, to compute forces output byactuators70.Local memory224, such as RAM and/or ROM, is preferably coupled tomicroprocessor220 to store instructions formicroprocessor220 and store temporary and other data.
• Sensor interface226 may optionally be included indevice10 to convert sensor signals to signals that can be interpreted by themicroprocessor220 and/orhost computer12. For example,sensor interface226 can receive and convert signals from a digital sensor such as an encoder or from an analog sensor using an analog to digital converter (ADC). Such circuits, or equivalent circuits, are well known to those skilled in the art. Alternately,microprocessor220 orhost computer12 can perform these interface functions.Actuator interface228 can be optionally connected between the actuators ofdevice10 andmicroprocessor220 to convert signals frommicroprocessor220 into signals appropriate to drive the actuators.Interface228 can include power amplifiers, switches, digital to analog controllers (DACs), and other components well known to those skilled in the art. Power supply230 can optionally be coupled toactuator interface228 and/or the actuators to provide electrical power. Alternatively, actuators and other components can draw power from the bus208 (such as USB) from the host computer. Or, power can be stored and regulated bydevice10 and used when needed to drive the actuators.
• Sensors72 sense the position, motion, and/or other characteristics of particular controls ofdevice10 as described above.Sensors72 provide signals tomicroprocessor220 including information representative of those characteristics. Thesensor72 orsensor interface226 can optionally provide sensor signals directly tocomputer12 as shown by busses209aand209b. Example of sensors suitable for embodiments described herein are digital rotary optical encoders, Hall effect sensors, linear optical encoders, analog sensors such as potentiometers, optical sensors such as a lateral effect photo diode, velocity sensors (e.g., tachometers) and/or acceleration sensors (e.g., accelerometers). Furthermore, either relative or absolute sensors can be employed.
• Actuators70 transmit forces to particular controls ofdevice10 in one or more directions along one or more degrees of freedom in response to signals output bymicroprocessor220 and/orhost computer12, i.e., they are “computer controlled.”Actuators70 include a magnetorheological brake as described in greater detail above.
• Themanipulandum56 can be a variety of different objects or manipulandums that are manipulated by a user and which can receive haptic feedback. For example,manipulandum56 can be a crank arm of a fishing pole device, pedals of bicycle simulator, or a knob. Manipulandum can be in other embodiments a joystick, mouse, steering wheel, stylus, or other object. The housing of theentire device10 can also be actuated, e.g. with vibrotactile sensations.
• Other input devices234 can optionally be included indevice10 and send input signals tomicroprocessor220 and/orhost computer12. Such input devices can include buttons, dials, knobs, switches, voice recognition hardware (with software implemented by host12), or other input mechanisms as described above. Safety or “deadman”switch236 can be included in some embodiments ofdevice10 to provide a mechanism to allow a user to override and deactivate forces output byactuators70, or require a user to activateactuators70, for safety reasons.
• While this invention has been described in terms of several preferred embodiments, it is contemplated that alterations, permutations, and equivalents thereof will become apparent to those skilled in the art upon a reading of the specification and study of the drawings. Furthermore, certain terminology has been used for the purposes of descriptive clarity, and not to limit the present invention. It is therefore intended that the following appended claims include all such alterations, permutations and equivalents as fall within the true spirit and scope of the present invention.

Claims (1)

1. A haptic feedback interface device manipulated by a user and providing input signals to a host computer, the interface device comprising:

a manipulandum physically contacted by said user and moveable in at least one degree of freedom;

a sensor that senses a position of said manipulandum in said at least one degree of freedom and outputs a sensor signal, wherein a representation of said sensor signal is provided to said host computer; and

a brake including a fluid having a viscosity that can be varied by adjusting an electromagnetic field in said fluid, wherein said electromagnetic field is adjusted by modulating an electric current, wherein a resistive force on said manipulandum is controlled by adjusting said current and thereby adjusting said viscosity.

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