Method and Apparatus for Compensating for Position Slip in Interface Devices

• US 20080303789A1
• Filed: 08/14/2008
• Published: 12/11/2008
• Est. Priority Date: 05/11/1999
• Status: Active Grant

• Current Assignee: Immersion Corporation
• Original Assignee: Immersion Corporation
• Inventors: Martin, Kenneth M., Schena, Bruce M., Braun, Adam C., Tierling, Kollin M.
• Granted Patent: US 8,103,472 B2
• Time in Patent Office: Days
• US Class Current: 345/156
• CPC Class Codes: A63F 2300/1018 Calibration; Key and button assignment
• CPC Class Codes: A63F 2300/1037 being specially adapted for converting control signals received from the game device into a haptic signal, e.g. using force feedback
• CPC Class Codes: G06F 3/016 Input arrangements with force or tactile feedback as computer generated output to the user

Abstract

Method and apparatus for compensating for position slip in interface devices that may occur between a manipulandum and a sensor of the device due to a mechanical transmission. A device position delta is determined from a sensed position of a manipulandum of an interface device. It is determined if position slip has occurred caused by a change in position of the manipulandum that was not sensed by a sensor of the interface device, typically caused by a mechanical transmission between sensor and manipulandum. If position slip has occurred, an error in the sensed position caused by the position slip is corrected by adjusting the sensed position to take into account the position slip. The adjusted position delta is used as the position of the manipulandum and the display of objects controlled by the interface device are accordingly compensated.

Claims

1. A method comprising:

determining a device position delta from a sensed position of a manipulandum of an interface device in a degree of freedom, the position delta indicating a change in an actual position of the manipulandum;

determining if a position slip has occurred in a position sensing system, the position slip caused by a change in position of the manipulandum not sensed by a sensor of the interface device; and

correcting an error in the sensed position caused by the position slip by adjusting the sensed position to take into account the position slip, and using the adjusted position as the actual position of the manipulandum.

2. A method as recited in claim 1 wherein the determining if the position slip has occurred comprises checking a reference signal from a reference sensor coupled to the interface device, the reference sensor detecting a position of a reference location of the manipulandum.

3. A method as recited in claim 1 further comprising determining a computation value from the device position delta, and outputting the computation value.

4. A method as recited in claim 3 further comprising disregarding the position slip when determining the computation value.

5. A method as recited in claim 1 further comprising using the sensed position of the manipulandum as the actual position of the manipulandum if the manipulandum is not moving in the degree of freedom.

6. A method as recited in claim 1 wherein the position slip comprises slip caused by a mechanical transmission coupled between the sensor and the manipulandum.

7. A method as recited in claim 6 wherein the mechanical transmission comprises a drive selected from the group consisting of a gear drive, a belt drive, and a capstan drive.

8. A device comprising:

a manipulandum movable in at least one degree of freedom;

a position sensor operative to detect a position of the manipulandum in the at least one degree of freedom;

a mechanical transmission coupled between the manipulandum and the position sensor; and

a reference sensor operative to detect a motion of at least one reference location of the manipulandum.

9. A device as recited in claim 8 wherein the mechanical transmission comprises a gear drive.

10. A device as recited in claim 8 wherein the mechanical transmission comprises a belt drive.

11. A device as recited in claim 8 wherein the position sensor comprises a relative digital encoder.

12. A device as recited in claim 8 further comprising a local microprocessor, the local microprocessor operable to receive the reference signal and operable to adjust the detected position of the manipulandum if the position slip has occurred.

13. A device as recited in claim 12 wherein the local microprocessor is operable to determine a computation value from a position delta determined from the position, adjusting the computation value if the position slip has occurred, the computation value.

14. A computer-readable medium on which is encoded program code to cause a processor to execute a method, comprising:

determining a device position delta from a sensed position of a manipulandum of an interface device in a degree of freedom, the position delta indicating a change in an actual position of the manipulandum;

determining if a position slip has occurred in a position sensing system, the position slip caused by a change in position of the manipulandum not sensed by a sensor of the interface device; and

correcting an error in the sensed position caused by the position slip by adjusting the sensed position to take into account the position slip, and using the adjusted position as the actual position of the manipulandum.

15. The computer-readable medium as recited in claim 14 wherein the determining if the position slip has occurred comprises checking a reference signal from a reference sensor coupled to the interface device, the reference sensor detecting a position of a reference location of the manipulandum.

16. The computer-readable medium as recited in claim 14 further comprising determining a computation value from the device position delta, and outputting the computation value.

17. The computer-readable medium as recited in claim 16 further comprising determining a force having a magnitude and a direction at least partially based on the computation value, and outputting the force with an actuator disposed within the interface device.

18. The computer-readable medium as recited in claim 14 further comprising performing the determining a device position, the determining if a position slip has occurred, and the correcting an error over a plurality of iterations, and adjusting the sensed position by an amount which gradually reduces the error in the sensed position over the plurality of iterations.

19. The computer-readable medium as recited in claim 14 further comprising using the sensed position of the manipulandum as the actual position of the manipulandum if the manipulandum is not moving in the degree of freedom.