Method and Apparatus for Detecting Object Orientation and Position

• US 20070270722A1
• Filed: 02/26/2007
• Published: 11/22/2007
• Est. Priority Date: 07/12/2005
• Status: Active Grant

• Current Assignee: The Alfred E. Mann Institute For Biomedical Engineering At The University Of Southern California (University of Southern California)
• Original Assignee: Alfred E MANN Institute For Biomedical Engineering At The University of Southern California, Southern California
• Inventors: Tan, Wei, Loeb, Gerald
• Granted Patent: US 7,970,477 B2
• Time in Patent Office: Days
• US Class Current: 600/595
• CPC Class Codes: A61B 2560/0219 of externally powered implanted units
• CPC Class Codes: A61B 2562/0223 Magnetic field sensors
• CPC Class Codes: A61B 2562/162 Capsule shaped sensor housings, e.g. for swallowing or implantation
• CPC Class Codes: A61B 5/06 Devices, other than using radiation, for detecting or locating foreign bodies for removing same A61B17/50 ; determining position of probes within or on the body of the patient
• CPC Class Codes: A61B 5/1114 Tracking parts of the body
• CPC Class Codes: A61B 5/1116 Determining posture transitions
• CPC Class Codes: A61B 5/1121 Determining geometric values, e.g. centre of rotation or angular range of movement
• CPC Class Codes: A61B 5/6861 Capsules, e.g. for swallowing or implanting
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: A61N 1/36003 of motor muscles, e.g. for walking assistance

Abstract

A signal transmitting and receiving system to track the position and orientation of limb segments in order to provide feedback information for the control of the limb movement. The user will generally be seated in a wheelchair that provides a structure upon which orthogonal and/or non-orthogonally oriented coils can be mounted and energized selectively so as to create variously oriented magnetic fields. Multiple wireless sensors injected into the limb detect the local field strength and send information telemetrically to a central controller. The controller extracts information about the position and orientation of each limb segment by combining signals from various sensors according to calibration information and optimal filtering methods for extracting information from multiple nonlinear sensors in mechanically constrained systems.

Claims

1. A position and orientation detecting system to measure movement of a limb, comprising:

a) at least one magnetic field source configured to be located external to the limb and to generate a magnetic field;

b) a plurality of physically separated, non-orthogonally oriented capsules configured to be implanted within the limb, each having a sensor configured to sense the magnetic field and to telemetrically transmit a signal corresponding to the sensed magnetic field; and

c) a controller configured to receive the transmitted signals, to compute the position and orientation of the limb based on the transmitted signals, and to generate information useful in controlling movement of the limb based on the transmitted signals.

2. The system of claim 1, wherein the magnetic field source comprises an AC source.

3. The system of claim 2, wherein the magnetic field source comprises a transmitter coil for magnetic field generation.

4. The system of claim 3, wherein the transmitted signals each comprise phase data.

5. The system of claim 4, wherein the phase data is determined from additive effects of two synchronized RF fields.

6. The system of claim 4, wherein the transmitter coil is energized by an asymmetrical current waveform.

7. The system of claim 6, wherein the phase data is determined from the sign of the largest signal sensed by the sensor that transmitted the phase data.

8. The system of claim 3, wherein each sensor includes a sensor coil to sense the magnetic field.

9. The system of claim 8, wherein each sensor coil is configured to also function as an antenna for a limb stimulator.

10. The system of claim 9, wherein the transmitter coil is configured to also function as an antenna to transmit data to a limb stimulator.

11. The system of claim 10, wherein each sensor coil is implanted within the limb at a location that is based on a clinical application.

12. The system of claim 1, wherein each sensor comprises a single coil wrapped around two ferrite rods, an integrated circuit chip and a micro-PCB board.

13. The system of claim 12, wherein each capsule includes a stimulator assembly configured to provide stimulation of limb muscle.

14. The system of claim 8, wherein each sensor coil is orientated non-orthogonally relative to the other sensor coils and/or the transmitter coil.

15. The system of claim 14, wherein the controller comprises a composite optimization algorithm and is configured to solve for a constraint involved in configuring the coils.

16. The system of claim 8, wherein the controller is configured to apply a global optimization algorithm to minimize local minimum points.

17. The system of claim 16, wherein the global optimization technique comprises a genetic algorithm.

18. The system of claim 17, wherein the global optimization technique further comprises a gradient-based optimization technique.

19. The system of claim 8, wherein the controller comprises a linear approximation technique to cancel muscle deformation.

20. A position and orientation detecting system to measure movement of a limb, comprising:

a) a plurality of magnetic field sources configured to be located at physically separated positions external to the limb and to generate a plurality of magnetic fields;

b) at least one capsule configured to be implanted within the limb having a sensor configured to sense the magnetic fields and to telemetrically transmit a signal corresponding to the sensed magnetic field; and

c) a controller configured to receive the transmitted signal, to determine the position and orientation of the limb, and to generate information useful in controlling movement of the limb.

21. The system of claim 20, wherein the magnetic field generating sources comprises AC sources.

22. The system of claim 21, wherein each of the magnetic field sources comprises a transmitter coil for magnetic field generation.

23. The system of claim 22, wherein the transmitted signal comprises phase data.

24. The system of claim 23, wherein the phase data is determined from additive effects of two synchronized RF fields.

25. The system of claim 23, wherein the transmitter coils are each energized by an asymmetrical current waveform.

26. The system of claim 25, wherein the phase data is determined from the sign of the largest signal sensed by the sensor from the energized transmitter coil.

27. The system of claim 22, wherein the sensor further comprises a sensor coil to sense the magnetic field.

28. The system of claim 27, wherein the sensor coil is configured to also function as an antenna to stimulate a limb muscle.

29. The system of claim 27, wherein the transmitter coils are configured to also function as antennas to transmit signals to a limb stimulator.

30. The system of claim 27, wherein the transmitter coils are positioned at locations that are based on a clinical application.

31. The system of claim 30, wherein the transmitter coils are placed at different locations.

32. The system of claim 20, wherein the sensor comprises of a single coil wrapped around two ferrite rods, an integrated circuit chip and a micro-PCB board.

33. The system of claim 32, wherein the capsule includes a stimulator assembly configured to provide stimulation of limb muscle.

34. The system of claim 27, wherein each transmitter coil is oriented non-orthogonally relative to the other transmitter coils and/or the sensor coil.

35. The system of claim 34, wherein the controller comprises a composite optimization algorithm and is configured to solve for a constraint involved in configuring the coils.

36. The system of claim 27, wherein the controller is configured to apply a global optimization algorithm to minimize local minimum points.

37. The system of claim 36, wherein the global optimization technique comprises a genetic algorithm.

38. The system of claim 37, wherein the global optimization technique further comprises a gradient-based optimization technique.

39. The system of claim 27, wherein the controller comprises a linear approximation technique to cancel muscle deformation.

40. A position and orientation detecting system to measure movement of a limb, comprising:

a) a plurality of magnetic field sources configured to be located at physically separated positions external to the limb and to generate a plurality of magnetic fields;

b) a plurality of physically separated, non-orthogonally oriented capsules configured to be implanted within the limb, each having a sensor configured to sense the magnetic fields and to telemetrically transmit a signal corresponding to sensed magnetic fields; and

c) a controller configured to receive the transmitted signals, to determine the position and orientation of the limb based on the transmitted signals, and to generate information useful in controlling movement of the limb.

41. The system of claim 40, wherein the magnetic field generating sources are AC sources.

42. The system of claim 40, wherein each of the magnetic field sources includes a transmitter coil for magnetic field generation.

43. The system of claim 41, wherein the transmitted signals each include phase data of the sensed signals.

44. The system of claim 43, wherein the phase data is determined from additive effects of two synchronized RF fields.

45. The system of claim 43, wherein the transmitter coils are each energized by an asymmetrical current waveform.

46. The system of claim 45, wherein the phase data is determined from the sign of the largest signal sensed by the sensor that transmitted the phase data from the energized transmitter coil.

47. The system of claim 42, wherein each of the sensors further includes a sensor coil to sense the magnetic fields.

48. The system of claim 47, wherein each sensor coil is configured to also function as an antenna to stimulate a limb muscle.

49. The system of claim 47, wherein each transmitter coil is configured to also function as an antenna to transmit data to a limb muscle stimulator.

50. The system of claim 47, wherein the transmitter coils are positioned at locations that are based on a clinical application.

51. The system of claim 50, wherein the transmitter coils are placed at different locations.

52. The system of claim 39, wherein each sensor comprises a single coil wrapped around two ferrite rods, an integrated circuit chip and a micro-PCB board.

53. The system of claim 52, wherein each capsule includes a stimulator assembly configured to provide stimulation of limb muscle.

54. The system of claim 47, wherein each transmitter coil is oriented non-orthogonally relative to the other transmitter coils and/or the sensor coils.

55. The system of claim 54, wherein the comprises a composite optimization algorithm and is configured to solve for a constraint involved in configuring the coils.

56. The system of claim 47, wherein the controller is configured to apply a global optimization algorithm to minimize local minimum points.

57. The system of claim 56, wherein the global optimization technique includes a genetic algorithm.

58. The system of claim 57, wherein the global optimization technique further includes a gradient-based optimization technique.

59. The system of claim 47, wherein the controller includes a linear approximation technique to cancel muscle deformation.