초록 ▼

Improvements in accurately sensing a user manipulandum of a force feedback device. A force feedback device, coupled to a host computer, includes an actuator for outputting forces on a manipulandum and a sensor for detecting a position of the manipulandum. In one feature, a raw sensor value represent

Improvements in accurately sensing a user manipulandum of a force feedback device. A force feedback device, coupled to a host computer, includes an actuator for outputting forces on a manipulandum and a sensor for detecting a position of the manipulandum. In one feature, a raw sensor value representing manipulandum position is adjusted based on compliance between sensor and manipulandum, where the adjustment can be based on a compliance constant and an output force. In another feature, a range of motion of the manipulandum is dynamically calibrated from startup. One boundary value of an assigned initial range is set equal to a received sensor value if the sensor value is outside the initial range, and the other boundary value is adjusted to maintain the size of the initial range unless the other boundary value has already been sensed outside the initial range. In another feature, manipulandum position is accurately sensed by filtering raw sensor values for overshoot values occurring at limits to manipulandum motion and using the filtered value in the dynamic calibration. In another feature, sensing inaccuracies caused by compliance in the device are decreased by normalizing a raw sensor value to a normalized range of motion that includes a saturation zone at each end of the range that adjusts sensor values over a saturation level to the saturation level.

대표청구항 ▼

1. A method comprising: receiving a sensor signal by a processor in communication with a memory, the sensor signal comprising a raw sensor value from a sensor, the raw sensor value associated with a position of a manipulandum in a range of motion;calculating an adjusted sensor value by the processor

1. A method comprising: receiving a sensor signal by a processor in communication with a memory, the sensor signal comprising a raw sensor value from a sensor, the raw sensor value associated with a position of a manipulandum in a range of motion;calculating an adjusted sensor value by the processor, the adjusted sensor value based at least in part on the raw sensor value and a compliance constant, the compliance constant predetermined based on a compliance between the sensor and the manipulandum; andoutputting an output signal by the processor, the output signal comprising the adjusted sensor value. 2. The method of claim 1, wherein the adjusted sensor value is calculated based at least in part on current output force. 3. The method of claim 1, further comprising determining a closed-loop position-dependent force by the processor, the closed-loop position-dependent force based at least in part on the raw sensor value. 4. The method of claim 1, further comprising transmitting forces from an actuator to the manipulandum with a belt drive. 5. The method of claim 1, further comprising filtering, by the processor, the raw sensor value for overshoot sensor values occurring at limits to the range of motion of the manipulandum. 6. The method of claim 1, further comprising calibrating, by the processor, the range of motion of the manipulandum by adjusting minimum and maximum values of the range of motion based at least in part on an extent of motion of the manipulandum up to a designated time. 7. The method of claim 1, further comprising normalizing, by the processor, the raw sensor value to a normalized range of motion, wherein the adjusted sensor value is further associated with the normalized raw sensor value. 8. A device comprising: a manipulandum;a linkage mechanism providing a degree of freedom to the manipulandum;a sensor operable to sense a position of the manipulandum in the degree of freedom and to output a raw sensor value representing the position; anda processor, operable to: receive a sensor signal from the sensor, the sensor signal comprising the raw sensor value;calculate an adjusted sensor value based at least in part on the raw sensor value and a compliance constant, the compliance constant predetermined based on a compliance between the sensor and the manipulandum; andoutput an output signal comprising the adjusted sensor value. 9. The device of claim 8, wherein the linkage mechanism includes a chain of four rotatably-coupled members coupled to ground at each end of the chain. 10. The device of claim 8, further comprising an actuator coupled to the linkage mechanism, the actuator operative to output a force in the degree of freedom. 11. The device of claim 9, further comprising a belt drive transmission coupled between the actuator and the linkage mechanism. 12. The device of claim 8, wherein the sensor comprises a relative digital encoder. 13. The device of claim 8, wherein the sensor is coupled to the actuator such that the sensor is operable to detect rotation of a shaft of the actuator. 14. The device of claim 8, wherein the processor is operable to calibrate a range of motion of the manipulandum by adjusting minimum and maximum values of the range of motion based at least in part on an extent of motion of the manipulandum up to a designated time. 15. The device of claim 8 wherein the processor is operable to determine a closed-loop force based at least in part on the raw sensor value. 16. A non-transitory computer-readable medium on which is encoded program code configured to cause a processor to execute a method comprising: receiving a sensor signal comprising a raw sensor value from a sensor, the raw sensor value associated with a position of a manipulandum in a range of motion;calculating an adjusted sensor value based at least in part on the raw sensor value and a compliance constant, the compliance constant predetermined based on a compliance between the sensor and the manipulandum; andoutputting an output signal comprising the adjusted sensor value. 17. The non-transitory computer-readable medium of claim 16, wherein the adjusted sensor value is calculated based at least in part on a current output force. 18. The non-transitory computer-readable medium of claim 16, further comprising determining a closed-loop position-dependent force based at least in part on the raw sensor value. 19. The non-transitory computer-readable medium of claim 16, further comprising transmitting forces from an actuator to the manipulandum with a belt drive. 20. The non-transitory computer-readable medium of claim 16, further comprising filtering the raw sensor value for overshoot sensor values occurring at limits to the range of motion of the manipulandum. 21. The non-transitory computer-readable medium of claim 16, further comprising calibrating the range of motion of the manipulandum by adjusting minimum and maximum values of the range of motion based at least in part on a extent of motion of the manipulandum up to a designated time.