MOTION CONTROL SYSTEM SELF-CALIBRATING

• US 20110148331A1
• Filed: 12/23/2009
• Published: 06/23/2011
• Est. Priority Date: 12/23/2009
• Status: Active Grant

• Current Assignee: ClearMotion Acquisition I LLC
• Original Assignee: Bose Corporation
• Inventors: Xu, Yongkai, Parison, James A. JR., Sangermano, Antonio II, Coey, Tyson Curtis
• Granted Patent: US 8,466,639 B2
• Time in Patent Office: Days
• US Class Current: 318/244
• CPC Class Codes: B60N 2/02246 Electric motors therefor
• CPC Class Codes: B60N 2/0244 with logic circuits
• CPC Class Codes: B60N 2210/50 Inertial sensors
• CPC Class Codes: B60N 2220/10 using a database
• CPC Class Codes: B60N 2230/30 Signal processing of sensor data

Abstract

A motion control system including components such as an accelerometer for detecting zero force positions and for self-calibrating the motion control system. The motion control system may be implemented in an active seat suspension.

Claims

1. A method for self-calibrating a motion control system, comprising:

providing, by a position detector associated with the motion control system position information of an armature;

providing a motion directing calibration signal of pre-determined frequency content, to cause a motion control system to provide current to a plurality of phases of a multiphase motor, the multiphase motor comprising the armature;

commutating current provided to the plurality of phases so that the net force with the pre-determined frequency content is zero if the actual position of the armature corresponds to the position information; and

detecting motion, at the pre-determined frequency, of the armature resulting from the motion directing signal.

2. A method for calibrating a motion control system according to claim 1, wherein the predetermined frequency content comprises frequencies outside the normal range of operation of the motion control system.

3. A method for calibrating a motion control system according to claim 1, wherein the detecting comprises filtering an acceleration measurement according to the predetermined frequency content.

4. A method for calibrating a motion control system according to claim 1, further comprising:

in the event that that motion resulting from the armature is detected, modifying the position information.

5. A method according to claim 1, wherein the detecting comprises measuring the acceleration of the armature.

6. A method according to claim 1, wherein the detecting comprises detecting audible vibration resulting from motion of the armature.

7. A method according to claim 1, further comprising:

simultaneously operating the motion control system in a conventional manner, the conventional manner comprising

receiving as input a desired armature position;

determining a motion that will cause the position indicated by the position information to match the desired armature position;

determining a force required to effect the motion; and

applying the required force to the armature.

8. A self calibrating motion control system comprising:

a motor comprising an armature and a plurality of phases;

a position sensor to provide position information of the armature;

a calibration signal source to provide a signal directing a motion control system to provide current to the plurality of phases;

a commutator to commutate current provided to the plurality of phases so that the net force resulting from the plurality of phases is zero if the actual position of the armature corresponds to the position information; and

a motion detector to detect motion of the armature resulting from the motion directing signal.

9. A self calibrating motion control system according to claim 8, further comprising circuitry to modify the position information, and wherein the commutator is further to commutate current provided to the plurality of phases so that the net force resulting from the plurality of phases is zero if the actual position of the armature corresponds to the modified position information.

10. A self calibrating motion control system according to claim 8, wherein the motion detector comprises an accelerometer.

11. A self calibrating a motion control system according to claim 8, wherein the motion detector comprises a microphone.

12. A calibration device for use in a motion control system according to claim 8, further comprising circuitry to modify the position information and wherein the commutator is further to commutate current provided to the plurality of phases so that the net force resulting from the plurality of phases is zero if the actual position of the armature corresponds to the modified position information.

13. A method comprising:

applying, at a first frequency, a force to an armature of a motor to move the armature through a range of positions;

determining, by a position sensor, an indicated position of the armature;

exciting, at a frequency higher than the first frequency, a coil of the motor;

measuring the acceleration of the armature;

filtering the acceleration of the armature to obtain a filtered acceleration measurement;

determining when the filtered acceleration measurement is zero; and

when the filtered acceleration measurement is zero, recording the indicated position.

14. A method according to claim 13, wherein the applying is performed by a linear actuator.

15. A method according to claim 13, wherein the exciting is performed by a first force source and the applying is performed by a second force source.

16. A method according to claim 15, wherein the second force source is gravity.

17. A method according to claim 13, wherein the filtering comprises band pass filtering.

18. A method according to claim 13, further comprising calculating the root mean squared value of the acceleration.

19. A method according to claim 13, wherein the method is implemented in an active vehicle seat suspension.

20. A method according to claim 19, wherein the force is applied by an air spring.

21. A method according to claim 13, wherein the force is applied to a plant mechanically coupled to the armature.

22. A method according to claim 13, further comprising commutating the motor responsive to the measuring.

31. A method according to claim 13, wherein the determining when the filtered acceleration measurement is zero comprises determining when the derivative of the filtered acceleration measurement changes sign.

23. A motion control apparatus comprising:

a motor, comprising an armature;

a force source, distinct from the motor, for moving the armature through a range of motion;

a position detector, for detecting the position of the armature;

an accelerometer, for providing a measurement of the acceleration of the armature;

a filter, for filtering the measurement; and

circuitry for associating a detected position with an acceleration measurement of zero.

24. A motion control apparatus according to claim 23, further comprising a plant mechanically coupling the second force source and the armature.

25. A motion control apparatus according to claim 23, wherein the filter is a band pass filter.

26. A motion control apparatus according to claim 23, further comprising circuitry for calculating the root mean squared value of the measurement of the acceleration.

27. A motion control apparatus according to claim 23, wherein the motor is a multiphase motor.

28. A motion control apparatus according to claim 27, further comprising commutating circuitry for commutating the motor responsive to the acceleration measurement.

29. An active vehicle seat suspension system, comprising:

a vehicle seat;

an actuator for controlling the motion of the vehicle seat, the actuator comprising an armature;

a position detector to provide position information of the armature; and

a self-calibration system for the active vehicle seat suspension system comprising a force source independent of the actuator to move the vehicle seat;

a current source to provide current to the actuator at a predetermined frequency;

a commutator to commutate the current so that the if the position information is accurate, the actuator applies a predetermined amount of force, and

an accelerometer for measuring the acceleration of the armature; and

a filter, for filtering the acceleration of the armature.

30. An active vehicle seat suspension system according to claim 29, wherein the predetermined amount of force is zero.