Position sensing methods for interface devices
First Claim
1. A method for calibrating a sensed range of motion of a manipulandum of an interface device, the method comprising:
- providing a predetermined initial range of movement for said manipulandum when said interface device is initially powered, said initial range including two boundary values, said boundary values including a maximum value and a minimum value;
receiving a sensor value representing a position of said manipulandum of said interface device in said range of movement as said manipulandum is moved;
setting said maximum value or said minimum value to said received sensor value if said received sensor value is outside said initial range; and
adjusting said other of said boundary values not set in setting said maximum value or said minimum value to maintain said initial range between said maximum value and said minimum value unless said other of said boundary values has been previously detected to be outside said initial range.
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Abstract
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.
217 Citations
18 Claims
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1. A method for calibrating a sensed range of motion of a manipulandum of an interface device, the method comprising:
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providing a predetermined initial range of movement for said manipulandum when said interface device is initially powered, said initial range including two boundary values, said boundary values including a maximum value and a minimum value;
receiving a sensor value representing a position of said manipulandum of said interface device in said range of movement as said manipulandum is moved;
setting said maximum value or said minimum value to said received sensor value if said received sensor value is outside said initial range; and
adjusting said other of said boundary values not set in setting said maximum value or said minimum value to maintain said initial range between said maximum value and said minimum value unless said other of said boundary values has been previously detected to be outside said initial range. - View Dependent Claims (2, 3, 4, 9, 10, 11)
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5. A method for calibrating a sensed range of motion of a manipulandum of an interface device, said interface device in communication with a host computer, the method comprising:
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providing a predetermined initial range of movement for said manipulandum, said initial range including two boundary values, said boundary values including a maximum value and a minimum value;
receiving a sensor value representing a position of said manipulandum of said interface device in said range of movement as said manipulandum is moved;
setting said maximum value or said minimum value to said received sensor value if said received sensor value is outside said initial range; and
adjusting said maximum value or said minimum value that was not set to said received sensor value to maintain said initial range between said maximum value and said minimum value, unless said maximum value or said minimum value that was not set to said received sensor value has been previously detected to be outside said initial range. - View Dependent Claims (6, 7, 8, 12, 13, 14)
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15. A computer-readable medium including program instructions for calibrating a sensed range of motion of a manipulandum of an interface device, the program instructions performing steps comprising:
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providing a predetermined initial range of movement for said manipulandum when said interface device is initially powered, said initial range including two boundary values, said boundary values including a maximum value and a minimum value;
receiving a sensor value representing a position of said manipulandum of said interface device in said range of movement as said manipulandum is moved;
setting said maximum value or said minimum value to said received sensor value if said received sensor value is outside said initial range; and
adjusting said other of said boundary values not set in said setting the maximum value or said minimum value to maintain said initial range between said maximum value and said minimum value unless said other of said boundary values has been previously detected to be outside said initial range. - View Dependent Claims (16, 17, 18)
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Specification