Method and apparatus for providing high bandwidth force feedback with ...

1. A force feedback interface device for providing high-fidelity force sensations to a user of the device, said interface device being coupled to a host computer and allowing said user to interact with an application program implemented by said host computer, said force feedback interface device comprising:

a user object graspable by said user and movable in at least one rotary degree of freedom;

a sensor for reporting a locative signal to said host computer, said locative signal indicating a position of said user object within said rotary degree of freedom;

an actuator coupled to said user object and to said host computer, said actuator outputting forces on said user object in response to signals from said host computer such that said forces are in response to said locative signal and are coordinated with events within said application program, said actuator having a reduced cogging effect such that said forces felt by said user are substantially free of force pulsations caused by said cogging effect when said user object is moved in said rotary degree of freedom, said actuator comprising:

a housing;

a set of magnets rigidly coupled to said housing, said magnets provided on opposing surfaces of an interior of said housing and creating a magnetic field;

a rotor rotatably coupled to said housing and to said user object and positioned between said magnets, said rotor operative to rotate about an axis of rotation approximately parallel to faces of said magnets, said rotor including a shaft and a plurality of teeth spaced apart equally about a circumference of said shaft, wherein said teeth and said magnets are provided in a skewed, helical arrangement relative to each other such that as said rotor rotates about said axis, a portion of one of said teeth exits said magnetic field as a portion of a next consecutive tooth is entering said magnetic field; and

a coil, wherein an electric current flows through said coil to cause said rotor to rotate about said axis of rotation; and

a drive transmission coupled between said actuator and said user object, said drive transmission amplifying said forces output by said actuator on said user object.

2. A force feedback interface device as recited in claim 1 wherein said teeth of said rotor are skewed relative to said shaft of said rotor.

3. A force feedback interface device as recited in claim 2 wherein said teeth are skewed relative to said shaft by an angle measured as a percentage of slot width, wherein said slot width is a distance between two adjacent teeth of said rotor.

4. A force feedback interface device as recited in claim 1 wherein said teeth of said rotor are skewed relative to edges of said magnets.

5. A force feedback interface device as recited in claim 2 wherein said coil is provided on at least one of said teeth.

6. A force feedback interface device as recited in claim 1 wherein said teeth have edges approximately parallel to said axis of rotation and wherein edges of said magnets are skewed relative to said axis of rotation.

7. A force feedback interface device as recited in claim 1 wherein said teeth are skewed relative to said axis of rotation and wherein edges of said magnets are skewed relative to said axis of rotation.

8. A force feedback interface device as recited in claim 1 wherein said shaft is coupled to a member of a gimbal mechanism that is coupled to said user object.

9. A force feedback interface device as recited in claim 8 wherein said drive transmission includes a capstan drive mechanism that is coupled to said member, said capstan drive mechanism providing mechanical advantage to a torque output on said shaft such that said force provided by said actuator is amplified in magnitude when applied to said user object.

10. A force feedback interface device as recited in claim 9 wherein said capstan drive mechanism includes a cable for transmitting said force and provides low compliance and a high bandwidth transmission of forces from said actuator to said user object.

11. A force feedback interface device as recited in claim 10 wherein said actuator is a first actuator, and further comprising a second actuator having a second rotor similar to said rotor in said first actuator, said two actuators being grounded.

12. A force feedback interface device as recited in claim 1 wherein said actuator is a DC servo motor.

13. A force feedback interface device as recited in claim 12 wherein said actuator is a brush-type motor.

14. A force feedback interface device as recited in claim 12 wherein said actuator is a brushless motor.

15. A force feedback interface device manipulated by a user and communicating with a host computer system implementing a host application program, said host application program displaying images on a computer display apparatus, said host computer system updating said host application program in response to user manipulation of said interface device and commanding force feedback sensations on said user in response to said manipulations and in coordination with events in said host application program, said force feedback interface device comprising:

a user object movable in a degree of freedom by a user and being physically contacted by said user;

a gimbal mechanism rotationally coupled to a support, said gimbal mechanism providing a plurality of rotary degrees of freedom to said user manipulatable object with respect to said support;

a grounded actuator coupled between said gimbal mechanism and said support for applying a rotational force along a first one of said degrees of freedom to said user object in accordance with a force signal from said host computer, said force signal causing said force to be coordinated with said host application program, thereby causing a feel sensation that corresponds with a relevant event within said host application program, said actuator including a grounded magnet and a rotor having skewed teeth with respect to said magnet to reduce force pulsations caused by a cogging effect of said actuator during movement of said user object in said first degree of freedom and to provide said feel sensation as felt by said user substantially without said force pulsations caused by said cogging effect;

an amplification transmission coupled between said actuator and said gimbal mechanism, said amplification transmission amplifying said force provided by said actuator, said amplified force being applied to said user object; and

a sensor for detecting a position of said user object along at least one of said degrees of freedom and outputting locative signals to said host computer system, said locative signals including information representative of said position of said user object, wherein said host application program updates said images in response to said locative signals and said position of said user object and said user interacts with said host application program by moving said user object.

16. A force feedback interface device as recited in claim 15 wherein said actuator is a DC servo motor.

17. A force feedback interface device as recited in claim 16 wherein said actuator is a brush-type motor.

18. A force feedback interface device as recited in claim 15 wherein said actuator is a first grounded actuator and further comprising a second grounded actuator for applying a rotational force along a second degree of freedom to said user object in accordance with a force signal from said host computer, said second grounded actuator including a grounded magnet and a rotor skewed with respect to said magnet to reduce force pulsations caused by a cogging effect of said second actuator during movement of said user object in said second degree of freedom and to provide said feel sensation as felt by said user substantially without said force pulsations caused by said cogging effect.

19. A force feedback interface device as recited in claim 15 further comprising a device microprocessor, separate from said host computer system, for communicating with said host computer system via a communication bus by receiving a host force command from said host computer system, said host force command being output from said host computer system in response to and coordinated with events within said host application program, said microprocessor executing a local process in parallel with said execution of said host application program for receiving and decoding said host force command and outputting a force signal to said actuator in response to a decoded host command, wherein said local process is stored in a local memory separate from said host computer and accessible to said device microprocessor.

20. A force feedback interface device as recited in claim 15 wherein said amplification transmission includes a capstan drive mechanism, said capstan drive mechanism being coupled between a shaft of said rotor of said actuator and said user manipulable object and providing mechanical advantage to a torque output by said actuator.

21. A force feedback interface device as recited in claim 20 wherein said capstan drive mechanism includes a drum, a capstan pulley, and a cable, said drum being coupled to said gimbal mechanism and said pulley being coupled to said drum by said cable and to said shaft of said rotor.

22. A force feedback interface device as recited in claim 15 wherein said teeth of said rotor are skewed relative to said shaft of said rotor by an angle measured as a percentage of slot width, wherein said slot width is a distance between two adjacent teeth of said rotor.

23. A force feedback interface device manipulated by a user and communicating with a host computer system implementing a host application program, said host application program displaying images on a computer display apparatus, said host computer system updating said host application program in response to user manipulation of said interface device and commanding force feedback sensations on said user in response to said manipulations and in coordination with events in said host application program, said force feedback interface device comprising:

a user object movable in a degree of freedom by a user and being physically contacted by said user;

a gimbal mechanism rotationally coupled to a support, said gimbal mechanism providing a plurality of rotary degrees of freedom to said user manipulatable object with respect to said support;

a grounded actuator coupled between said gimbal mechanism and said support for applying a rotational force along a degree of freedom to said user object in accordance with a force signal, said force signal causing said force to be coordinated with said host application program, thereby causing a feel sensation that corresponds with a relevant event within said host application program;

a sensor for detecting a position of said user object along at least one of said degrees of freedom and outputting locative signals to said host computer system, said locative signals including information representative of said position of said user object, wherein said host application program updates said images in response to said locative signals and said position of said user object and said user interacts with said host application program by moving said user object; and

a device microprocessor, separate from said host computer system, for communicating with said host computer system via a communication bus by receiving a host force command from said host computer system, said host force command being output from said host computer system in response to and coordinated with events within said host application program, said microprocessor executing a local process in parallel with said execution of said host application program for receiving and decoding said host force command and outputting said force signal to said actuator in response to a decoded host command, wherein said local process is stored in a local memory separate from said host computer and accessible to said device microprocessor, and wherein said host commands include at least one of:

direct host commands for commanding said microprocessor to immediately output a desired force according to a force routine selected by said direct host command,

reflex commands for commanding said microprocessor to output a desired force according to a force routine selected by said reflex command and when said microprocessor determines that predetermined conditions have been met, and

custom profile commands for commanding said microprocessor to receive a set of data from said host computer to command said microprocessor to output a sequence of forces over time based on said set of data.

24. A force feedback interface device as recited in claim 23 wherein said actuator includes a grounded magnet and a rotor skewed with respect to said magnet to reduce a cogging effect of said actuator on provide a smoother feel to said user object as experienced by said user when said user object is moved in said degree of freedom than when said cogging effect is not reduced.

25. A force feedback interface device as recited in claim 23 wherein said direct host commands may command at least one of a jolt force, a spring force, a wobble force, and a damping force.

26. A force feedback interface device as recited in claim 23 wherein said predetermined conditions for said reflex commands include a selection of a button on said user object by said user.

27. A force feedback interface device as recited in claim 23 wherein said set of data used for said custom profile commands includes a predetermined set of force magnitudes and timing information instructing said microprocessor when to control said actuator to output said force magnitudes.