Hybrid 3-D probe tracked by multiple sensors

• US 6,611,141 B1
• Filed: 09/17/2001
• Issued: 08/26/2003
• Est. Priority Date: 12/23/1998
• Status: Expired due to Term

• Current Assignee: Stryker Corporation
• Original Assignee: Howmedica Leibinger Inc. (Stryker Corporation)
• Inventors: Schulz, Waldean A., Faul, Ivan
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US09/868,948
• Time in Patent Office: 708 Days
• Field of Search: 324/226, 324/227, 324/225, 324/207.11, 324/207.12, 324/207.14, 324/207.23, 324/260, 600/427, 600/425, 356/601, 356/614, 702/94, 702/150-153, 250/559.27
• US Class Current: 324/226
• CPC Class Codes: A61B 2034/107 Visualisation of planned trajectories or target regions
• CPC Class Codes: A61B 2034/2048 using an accelerometer or inertia sensor
• CPC Class Codes: A61B 2034/2051 Electromagnetic tracking systems
• CPC Class Codes: A61B 2034/2055 Optical tracking systems
• CPC Class Codes: A61B 2090/0818 Redundant systems, e.g. using two independent measuring systems and comparing the signals
• CPC Class Codes: A61B 2090/3995 Multi-modality markers
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49

Abstract

This invention is a system that tracks the 3-dimensional position and orientation of one or more bodies (20) in a volume by a light based as well as at least one non-light based mensuration sub-system. This overcomes the limitation of light based mensuration systems to the necessity of the bodies (20) to be in constant line-of-sight of its light based position sensors (26). The invention possesses most of the accuracy and stability of its light based position measurement sub-system (24, 26, 72), but can also work without direct line of sight either for short periods of time or within certain parts of the volume. It does so by incorporating other sensors (31, 34), such as inertial or magnetic, which are frequently recalibrated against the light based sub-system (24, 26, 72) while the bodies (20) are visible by the light based sub-system (24, 26, 72).

Claims

1. A system to track the three-dimensional position of an object within a defined volume comprising:

a first tracking system to determine a first indication of the position of the object;

a second tracking system independent of the first tracking system to determine a second indication of the position of the object;

a first circuit operative to compare the first indication of the position with the second indication of the position of the object;

a second circuit coupled to the first circuit and operative to determine a variance between the second indication of the position of the object and the first indication of the position of the object; and

a third circuit coupled to the first and second circuits and operative to update the variance.

2. The system of claim 1 wherein the variance is estimated if one of the first indication of the position of the object or the second indication of the position of the object cannot be determined.

3. The system of claim 1, wherein the first tracking system is electromagnetic.

4. The system of claim 3, wherein the electromagnetic system uses energy in the visible spectrum.

5. The system of claim 3, wherein the electromagnetic system uses energy in the infrared spectrum.

6. The system of claim 1, wherein the second tracking system is magnetic.

7. The system of claim 1, wherein the second tracking system is inertial.

8. The system of claim 1, wherein the system also comprises a fourth circuit coupled to the third circuit and operative to provide a warning if the variance exceeds a predetermined limit.

9. The system of claim 1, wherein the system also includes a fourth circuit coupled to the first and second circuits and operative to determine which of the first tracking system or the second tracking system is more accurate and which of the first tracking system or the second tracking system is less accurate.

10. The system of claim 9, wherein the system also includes a fifth circuit coupled to the fourth circuit and operative to calibrate the less accurate system to the more accurate system.

11. A method of guiding an object during a medical procedure, the method comprising the steps of:

providing a first tracking system to determine a first indication of the position of the object;

providing a second tracking system independent of the first tracking system to determine a second indication of the position of the object;

comparing the first indication of the position of the object and the second indication of the position of the object to determine a variance;

estimating a variance between the first indication of the position of the object and the second indication of the position of the object; and

updating the estimate of the variance.

12. The method of claim 11, wherein step of estimating of the variance is conducted if one of the first indication of the position of the object or the second indication of the position of the object cannot be determined.

13. The method of claim 11, wherein the first tracking system is electromagnetic.

14. The method of claim 13, wherein the electromagnetic system uses energy in the visible spectrum.

15. The method of claim 13, wherein the electromagnetic system uses energy in the infrared spectrum.

16. The method of claim 11, wherein the second tracking system is magnetic.

17. The method of claim 11, wherein the second tracking system is inertial.

18. The method of claim 11, wherein the system also comprises a step of warning if the variance exceeds a predetermined limit.

19. The method of claim 11, wherein the method also includes the step of determining which of the first tracking system or the second tracking system is the more accurate and which of the first tracking system or the second tracking system is less accurate.

20. The method of claim 19, wherein the method also includes the step of calibrating the less accurate system to the more accurate system.

21. A system to track the three dimensional position and orientation of an object within a defined space comprising:

an electromagnetic tracking system to determine the electromagnetic position and orientation of this object;

an inertial tracking system to determine the inertial position and orientation of the object;

means for comparing the electromagnetic position and orientation of the object and the inertial position and orientation of the object; and

means for estimating the variance of the inertial position and orientation of the object from the electromagnetic position and orientation of the object.

22. The system of claim 21 wherein the system further includes means for updating the variance estimate.

23. The system of claim 22, wherein the variance is estimated if the electromagnetic position of the object cannot be determined.

24. The system of claim 21, wherein the electromagnetic system uses energy in the visible spectrum.

25. The system of claim 21, wherein the electromagnetic system uses energy in the infrared spectrum.

27. The system of claim 21, wherein the system further includes a second circuit coupled to the first-named circuit and operative to determine which of the electromagnetic tracking system or the inertial tracking system is more accurate and which of the electromagnetic tracking system or the inertial tracking system is less accurate.

28. The system of claim 27, wherein the system further includes a third circuit coupled to the first-named circuit and the second circuit and operative to calibrate the less accurate system to the more accurate system.

26. The system of 21 wherein the system also comprises a means for warning if that variance estimate exceeds a predetermined limit.

29. A system to track the three-dimensional position of an object within a defined volume comprising:

a first tracking system to determine a first indication of the position of the object;

a second tracking system independent of the first tracking system to determine a second indication of the position of the object;

a first circuit operative to compare the first indication of the position with the second indication of the position of the object;

a second circuit coupled to the first circuit and operative to determine which of the first tracking system or the second tracking system is more accurate and which of the first tracking system or the second tracking system is less accurate; and

a third circuit coupled to the first and second circuits and operative to calibrate the less accurate system to the more accurate system.

30. The system of claim 29, wherein the system further includes a fourth circuit coupled to the first circuit and operative to determine a variance between the first indication of the position of the object and the second indication of the position of the object.

31. The system of claim 30, wherein the system further includes a fifth circuit coupled to the fourth circuit and operative to update the variance.

32. The system of claim 30, wherein the variance is updated if one of the first indication of the position of the object or the second indication of the position of the object cannot be determined.

33. The system of claim 29, wherein the first tracking system is electromagnetic.

34. The system of claim 33, wherein the electromagnetic system uses energy in the visible spectrum.

35. The system of claim 33, wherein the electromagnetic system uses energy in the infrared spectrum.

36. The system of claim 29, wherein the second tracking system is magnetic.

37. The system of claim 29, wherein the second tracking system is inertial.

38. The system of claim 30, wherein the system further includes a fifth circuit coupled to the fourth circuit and operative to warn if the variance exceeds a predetermined limit.

39. A system for determining a position of an object in a three dimensional volume, comprising:

an electromagnetic position determination system operative to develop a first indication of the position of the object based on a line-of-sight detection of electromagnetic energy;

a non-line-of-sight position determination system operative to develop a second indication of the position of the object;

a first circuit operative to compare the first indication to the second indication;

a second circuit coupled to the first circuit and operative to provide an electromagnetic position determination system accuracy estimate and a non-line-of-sight position determination system accuracy estimate; and

a third circuit coupled to the second circuit and operative to develop a warning when the accuracy estimate for either system exceeds a predetermined limit.

40. The system of claim 39, further including a fourth circuit coupled to the first circuit and operative to calibrate the non-line-of-sight position determination system to the electromagnetic position determination system.

41. The system of claim 39, wherein the electromagnetic position determination system also develops a first indication of the orientation of the object and the non-line-of-sight position determination system also develops a second indication of the orientation of the object.

42. The system of claim 39, wherein the second circuit is also operative to track the accuracy estimate of the non-line-of-sight position determination system while the electromagnetic position determination system is functioning;

and to apply a correction to the position of the object as determined by the non-line-of-sight position determination system when the electromagnetic position determination system is unable to accurately determine the position of the object.

43. The system as claimed in claim 39, wherein the electromagnetic system uses energy in the infrared spectrum.

44. The system as claimed in claim 39, wherein the electromagnetic system uses energy in the visible spectrum.

45. The system as claimed in claim 39, wherein the non-line-of-sight position determination system is magnetic.

46. The system as claimed in claim 45, wherein the magnetic non-line-of-sight position determination system comprises at least three orthogonally disposed magnetic flux detectors.

47. The system as claimed in claim 39, wherein the non-line-of-sight position determination system is inertial.

48. The system as claimed in claim 47, wherein the inertial non-line-of-sight position determination system comprises a plurality of accelerometers.

49. The system as claimed in claim 48, wherein the inertial non-line-of-sight position determination system comprises at least three orthogonally disposed accelerometers.

50. The system as claimed in claim 39, further comprising a second non-line-of-sight position determination system.

51. The system as claimed in claim 50, wherein the non-line-of-sight position determination systems are inertial and magnetic, respectively.

52. The system as claimed in claim 39, wherein the first circuit is further operative to average the first indication and the second indication.

53. The system as claimed in claim 39, wherein the electromagnetic position determining system further comprises a source of electromagnetic energy that is spaced from the object and wherein the object includes reflectors of the electromagnetic energy radiated from the source.

54. A system for determining a position of an object in a three dimensional volume, comprising:

an electromagnetic position determination system operative to develop a first indication of the position of the object based on a line-of-sight detection of electromagnetic energy; and

a magnetic position determination system operative to develop a second indication of the position of the object;

wherein the magnetic position determining system includes an independent magnetic field generator spaced from the object, magnetic flux detectors disposed in operative relationship to the object and within operative distance from the magnetic field generator, and electromagnetic energy emitters operatively associated with the magnetic field generator to enable the determination of the position of the magnetic field generator by the electromagnetic position determining system.

55. The system as claimed in claim 54, wherein the generator can be moved into a position whereby at least some of the emitters are a in line-of-sight relationship with the electromagnetic sensors to enable the determination of the position of the generator, and whereby the magnetic sensors operatively associated with the object are sufficiently within the magnetic flux emitted by the generator to provide accurate determinations of the position of the object.