Multi-axis tilt estimation and fall remediation

• US 20070038268A1
• Filed: 04/10/2006
• Published: 02/15/2007
• Est. Priority Date: 08/09/2005
• Status: Active Grant

• Current Assignee: Charles Stark Draper Laboratory Incorporated, Massachusetts Eye And Ear Infirmary (Foundation of The Massachusetts Eye and EAR Infirmary Incorporated)
• Original Assignee: Massachusetts Eye And Ear Infirmary (Foundation of The Massachusetts Eye and EAR Infirmary Incorporated)
• Inventors: Wall, Conrad, O'Neil, Edward, Sienko, Kathleen, Weinberg, Marc
• Granted Patent: US 8,092,398 B2
• Time in Patent Office: Days
• US Class Current: 607/62
• CPC Class Codes: A61H 3/00 Appliances for aiding patients or disabled persons to walk about apparatus for helping babies to walk A47D13/04; orthopaedic devices for correcting deformities of, or supporting, limbs A61F5/0102; exercising apparatus for the feet or toes A63B23/10; stairways or ramps E04F11/00

Abstract

Among other things, a vestibular prosthesis includes a wearable motion sensing system, the motion sensing system generating a motion signal indicative of a motion thereof, wherein the motion includes rotation about two distinct axes; a signal processor in communication with the motion sensing system, the signal processor being configured to generate an estimate of a tilt of the motion sensing system; and an actuator responsive to the estimate of the tilt made by the signal processor.

Claims

1. A vestibular prosthesis comprising:

a wearable motion sensing system, the motion sensing system generating a motion signal indicative of a motion thereof, wherein the motion includes rotation about two distinct axes;

a signal processor in communication with the motion sensing system, the signal processor being configured to generate an estimate of a tilt of the motion sensing system; and

an actuator responsive to the estimate of the tilt made by the signal processor.

2. The prosthesis of claim 1, further comprising a stimulator in communication with the actuator, the stimulator being configured to generate a stimulus signal based on the tilt of the motion sensing system.

3. The prosthesis of claim 1, wherein the motion sensing system further comprises accelerometers and gyroscopes.

4. The prosthesis of claim 3, wherein the signal processor is configured to generate a first estimate of the tilt based on output from the accelerometers, and to generate a second estimate of the tilt based on output from the gyroscopes.

5. The prosthesis of claim 4, wherein the signal processor is configured to generate a third estimate of the tilt based on the first estimate and the second estimate.

6. The prosthesis of claim 5, wherein the signal processor is configured to represent the first, second, and third estimates as quaternions.

7. The prosthesis of claim 5, wherein the signal processor is configured to generate:

the first estimate based on Euler angles relating a motion of the accelerometers to the tilt of the motion sensing system; and

the second estimate based on Euler angles relating motion of the gyroscopes to the tilt of the motion sensing system.

8. The prosthesis of claim 7, wherein the signal processor is configured to determine a first redundant Euler angle and a second redundant Euler angle, and generate the first estimate based further on the first redundant Euler angle, and generate the second estimate based on the second redundant Euler angle.

9. The prosthesis of claim 5, wherein the signal processor is configured to generate the third estimate by using a Kalman filter.

10. The prosthesis of claim 1, further comprising an airbag in communication with the actuator, wherein the signal processor is configured to cause the actuator to deploy the airbag when the tilt of the motion sensing system is within a pre-determined range, or when the motion has pre-determined characteristics.

11. A method of estimating a tilt of a wearer, the method comprising:

generating a motion signal indicative of rotations about at least two axes as experienced by the wearer;

processing the motion signal to generate an estimate of the tilt of the wearer.

12. The method of claim 11, further comprising providing an output signal to a nervous system of the wearer, the output signal being indicative of the estimate of the tilt of the wearer.

13. The method of claim 11, further comprising taking remedial action in response to the estimate of tilt of the wearer.

14. The method of claim 13, wherein taking remedial action comprises deploying an airbag worn by the wearer.

15. The method of claim 11, wherein generating a motion signal includes generating an accelerometer signal and generating a gyro signal, and processing the signal includes processing the accelerometer signal and processing the gyro signal.

16. The method of claim 15, wherein generating a motion signal includes generating a total signal based on the accelerometer signal and the gyro signal.

17. The method of claim 16, wherein processing the accelerometer signal includes determining an accelerometer quaternion, and processing the gyro signal includes determining a gyro quaternion.

18. The method of claim 16, wherein processing the accelerometer signal includes determining accelerometer Euler angles, and processing the gyro signal includes determining gyro Euler angles.

19. The method of claim 18, wherein processing the accelerometer signal further includes determining a first redundant Euler angle, and processing the gyro signal further includes determining a second redundant Euler angle.

20. The method of claim 16, wherein generating a total signal includes combining the accelerometer signal and the gyro signal by using a Kalman filter.