Calibration method and calibration device for a surgical referencing unit

• US 20080039868A1
• Filed: 06/28/2007
• Published: 02/14/2008
• Est. Priority Date: 07/05/2006
• Status: Active Grant

• Current Assignee: Aesculap AG (Lonza Group AG)
• Original Assignee: Aesculap AG (Lonza Group AG)
• Inventors: Link, Thomas, Goeggelmann, Andreas, Tuemmler, Hanns-Peter, Mintenbeck, Dieter
• Granted Patent: US 7,702,477 B2
• Time in Patent Office: Days
• US Class Current: 606/130
• CPC Class Codes: A61B 2017/00725 Calibration or performance testing
• CPC Class Codes: A61B 2034/2048 using an accelerometer or inertia sensor
• CPC Class Codes: A61B 2034/2055 Optical tracking systems
• CPC Class Codes: A61B 2034/2068 using pointers, e.g. pointers having reference marks for determining coordinates of body points
• CPC Class Codes: A61B 2034/207 Divots for calibration
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 90/36 Image-producing devices or illumination devices not otherwise provided for

Abstract

A calibration method and also a calibration device are proposed to enable a spatial position and/or orientation of a surgical referencing unit of a surgical navigation system fitted with at least one inertial sensor to be specified in relation to a spatial coordinate system.

Claims

1. Method for calibrating a spatial position and/or orientation of at least one surgical referencing unit of a surgical navigation system fitted with at least one inertial sensor in relation to a spatial coordinate system, comprising:

providing a calibration unit, the position and/or orientation data of which are determinable in relation to the coordinate system by the navigation system;

bringing the calibration unit and the at least one referencing unit into a one-to-one calibration position relative to one another, in which the calibration unit and the at least one referencing unit respectively assume a defined calibration position and/or orientation relative to one another;

determining calibration position and/or orientation data of the calibration unit in the calibration position by means of the navigation system;

calculating calibration position and/or orientation data of the referencing unit in the calibration position on the basis of the calibration position and/or orientation data of the calibration unit, and

assigning the calibration position and/or orientation data calculated for the at least one referencing unit in the calibration position to the at least one referencing unit.

2. Method according to claim 1, wherein a non-fixed coordinate system is predefined as coordinate system, and wherein an origin of the non-fixed coordinate system is predefined by the calibration position and/or orientation data of the at least one referencing unit or the calibration unit in the calibration position.

3. Method according to claim 1, wherein at least two referencing units are calibrated, wherein a non-fixed coordinate system is predefined as coordinate system, and wherein an origin of the non-fixed coordinate system is predefined by one of the at least two referencing units.

4. Method according to claim 1, wherein a spatially fixed origin of an absolute coordinate system is predefined, wherein the calibration unit is brought into an origin calibration position, in which the calibration unit is positioned in a defined relation to the fixed origin, and wherein origin position and/or orientation data of the calibration unit in the origin calibration position relative to the fixed origin are assigned to the calibration unit.

5. Method according to claim 1, wherein a calibration signal is generated when the calibration unit and the at least one referencing unit assume the calibration position.

6. Method according to claim 5, wherein the calibration signal is only generated after a holding time t_H, during which the calibration unit and the at least one referencing unit assume the calibration position without or substantially without any relative movement.

7. Method according to claim 5, wherein an actuating element is actuated in the calibration position, and wherein the calibration signal is only generated during or as a consequence of an actuation of the actuating element.

8. Method according to claim 7, wherein the actuating element is actuated by means of the calibration unit and/or the at least one referencing unit.

9. Method according to claim 7, wherein a key or a foot switch is used as actuating element.

10. Method according to claim 5, wherein only after the calibration signal is present, the calibration position and/or orientation data of the calibration unit in the calibration position are determined by means of the navigation system, the calibration position and/or orientation data of the at least one referencing unit in the calibration position are calculated and the calibration position and/or orientation data calculated for the at least one referencing unit in the calibration position are assigned to the at least one referencing unit.

11. Method according to claim 1, wherein an origin calibration signal is generated when the calibration unit assumes the origin calibration position.

12. Method according to claim 11, wherein the origin calibration signal is only generated after a holding time t_H—

_origin, during which the calibration unit assumes the origin calibration position without movement or substantially without movement.

13. Method according to claim 11, wherein in the origin calibration position an origin calibration actuating element is actuated, and wherein the origin calibration signal is only generated during or as a consequence of an actuation of the origin calibration actuating element.

14. Method according to claim 13, wherein the origin calibration actuating element is actuated by the calibration unit or a referencing device.

15. Method according to claim 13, wherein a key or foot switch is used as origin calibration actuating element.

16. Method according to claim 11, wherein the origin position and/or orientation data of the calibration unit in the origin calibration position in relation to the fixed origin are assigned to the calibration unit only after the origin calibration signal is present.

17. Method according to claim 1, wherein a navigation operation of the navigation system is enabled for tracking any movements of the at least one referencing unit only when all referencing units necessary for the navigation operation have been calibrated with the calibration unit in relation to a common coordinate system.

18. Method according to claim 17, wherein a navigation operation is restricted to a predefinable operating time t_operation.

19. Method according to claim 18, wherein the operating time t_operation automatically begins to run when all referencing units have been calibrated with the calibration unit in relation to a common coordinate system.

20. Method according to claim 18, wherein after expiry of the operating time t_operation, an optical and/or acoustic warning signal is emitted and/or the navigation operation is automatically terminated.

21. Method according to claim 18, wherein the operating time t_operation is monitored by the navigation system.

22. Method according to claim 18, wherein the operating time t_operation is restricted to a maximum time in the range of 1 second to 60 minutes.

23. Method according to claim 1, wherein a calibration unit fitted with at least one inertial sensor is provided, the position and/or orientation data of which are determinable in relation to the coordinate system by the navigation system.

24. Method according to claim 1, wherein the calibration unit and the at least one referencing unit respectively have at least one transmitting unit, and wherein with the at least one transmitting unit changes of the position and/or orientation data of the calibration unit and/or the at least one referencing unit are transmitted to the navigation system or to a detection device thereof.

25. Method according to claim 1, wherein for determination of the position and/or orientation data of the calibration unit and the at least one referencing unit, a navigation system is used, which comprises an evaluation unit configured in such a manner that absolute position and/or orientation data can be calculated for the calibration unit and the at least one referencing unit from acceleration values measured by means of the at least one inertial sensor.

26. Method according to claim 24, wherein position and/or orientation change data of the calibration unit and the at least one referencing unit are calculated from the measured acceleration values in relation to the coordinate system, and wherein absolute position and/or orientation data of the calibration unit and the at least one referencing unit are calculated from the calculated position and/or orientation change data in relation to the coordinate system.

27. Method according to claim 1, wherein an inertial sensor unit is used as at least one inertial sensor, that comprises at least three linear and three rotation acceleration sensors, with which accelerations and/or forces (F) acting on the calibration unit and/or the at least one referencing unit are measured as a function of time in three mutually linearly independent directions and around three mutually linearly independent rotational axes.

28. Surgical calibration device for calibrating a spatial position and/or orientation of at least one surgical referencing unit of a surgical navigation system fitted with at least one inertial sensor in relation to a spatial coordinate system, comprising:

a navigation system with a data processing unit, wherein the navigation system and the data processing unit are configured and programmed in such a manner that position and/or orientation data of the referencing unit are determinable in relation to the coordinate system;

a calibration unit, the position and/or orientation data of which are determinable in relation to the coordinate system by the navigation system,

wherein the calibration unit and the at least one referencing unit can be brought into a one-to-one calibration position relative to one another, in which the calibration unit and the at least one referencing unit respectively assume a defined calibration position and/or orientation relative to one another,

wherein the navigation system and the data processing unit are further configured and programmed in such a manner that position and/or orientation data of the calibration unit are determinable in relation to the coordinate system, that calibration position and/or orientation data of the referencing unit in the calibration position can be calculated on the basis of the calibration position and/or orientation data of the calibration unit, and that the calibration position and/or orientation data calculated for the at least one referencing unit in the calibration position can be assigned to the at least one referencing unit.

29. Surgical calibration device according to claim 28, wherein the navigation system and the data processing unit are further configured and programmed in such a manner that a non-fixed coordinate system is predefinable as coordinate system, and an origin of the non-fixed coordinate system is predefinable by the calibration position and/or orientation data of the at least one referencing unit or the calibration unit in the calibration position.

30. Surgical calibration device according to claim 28, wherein the navigation system and the data processing unit are further configured and programmed in such a manner that at least two referencing units can be calibrated, wherein a non-fixed coordinate system is predefinable as coordinate system, and an origin of the non-fixed coordinate system is predefinable by one of the at least two referencing units.

31. Surgical calibration device according to claim 28, wherein an origin calibration gauge is provided, and the navigation system and the data processing unit are further configured and programmed in such a manner that a spatially fixed origin of an absolute coordinate system defined by the origin calibration gauge is predefinable, that the calibration unit can be brought into an origin calibration position relative to the origin calibration gauge, in which position the calibration unit is positioned in a defined relation to the fixed origin, and that origin position and/or orientation data of the calibration unit in the origin calibration position in relation to the fixed origin can be assigned to the calibration unit.

32. Surgical calibration device according to claim 28, wherein a calibration signal generating device is provided for generation of a calibration signal when the calibration unit and the at least one referencing unit assume the calibration position.

33. Surgical calibration device according to claim 32, wherein the calibration signal generating device is configured in such a manner that the calibration signal is only generated after a holding time t_H, during which the calibration unit and the at least one referencing unit assume the calibration position without or substantially without any relative movement.

34. Surgical calibration device according to claim 32, wherein at least one actuating element is provided, which can be actuated in the calibration position, and that the calibration signal can only be generated with the calibration signal generating device during or as a consequence of an actuation of the at least one actuating element.

35. Surgical calibration device according to claim 34, wherein the at least one actuating element is arranged in such a manner that it can be actuated by means of the calibration unit and/or the at least one referencing unit.

36. Surgical calibration device according to claim 34, wherein the at least one actuating element comprises a key or a foot switch.

37. Surgical calibration device according to claim 34, wherein the at least one actuating element is arranged on the at least one referencing unit, on the calibration unit and/or on the origin calibration gauge.

38. Surgical calibration device according to claims 32, wherein the navigation system and the data processing unit are further configured and programmed in such a manner that only after the calibration signal is present, the calibration position and/or orientation data of the calibration unit in the calibration position can be determined by means of the navigation system, the calibration position and/or orientation data of the at least one referencing unit in the calibration position can be calculated and the calibration position and/or orientation data calculated for the at least one referencing unit in the calibration position can be assigned to the at least one referencing unit.

39. Surgical calibration device according to claim 28, wherein an origin calibration signal generating device is provided to generate an origin calibration signal when the calibration unit assumes the origin calibration position.

40. Surgical calibration device according to claim 39, wherein the origin calibration signal generating device is configured in such a manner that the origin calibration signal can only be generated after a holding time t_H—

_origin, during which the calibration unit assumes the origin calibration position without movement or substantially without movement.

41. Surgical calibration device according to claim 39, wherein an origin calibration actuating element is provided, which can be actuated in the origin calibration position, and that the origin calibration signal can only be generated during or as a consequence of an actuation of the origin calibration actuating element.

42. Surgical calibration device according to claim 41, wherein the origin calibration actuating element is arranged in such a manner that it can be actuated by the calibration unit, a referencing device or the origin calibration gauge.

43. Surgical calibration device according to claim 41, wherein the origin calibration actuating element comprises a key or foot switch.

44. Surgical calibration device according to claim 39, wherein the navigation system and the data processing unit are further configured and programmed in such a manner that the origin position and/or orientation data of the calibration unit in the origin calibration position in relation to the fixed origin can be assigned to the calibration unit only after the origin calibration signal is present.

45. Surgical calibration device according to claim 28, wherein the navigation system and the data processing unit are further configured and programmed in such a manner that a navigation operation of the navigation system can be enabled for tracking any movements of the at least one referencing unit only when all referencing units necessary for the navigation operation have been calibrated with the calibration unit in relation to a common coordinate system.

46. Surgical calibration device according to claim 45, wherein the navigation system comprises an operating time setting unit, with which a navigation operation can be restricted to a predefinable operating time t_operation.

47. Surgical calibration device according to claim 46, wherein the navigation system and the data processing unit are further configured and programmed in such a manner that the operating time t_operation, which is predefinable by means of the operating time setting unit, automatically begins to run when all referencing units have been calibrated with the calibration unit in relation to a common coordinate system.

48. Surgical calibration device according to claim 46, wherein a warning signal generating device is provided, with which after expiry of the operating time t_operation, an optical and/or acoustic warning signal can be emitted and/or with which the navigation operation can be automatically terminated.

49. Surgical calibration device according to claim 46, wherein the navigation system comprises an operating time monitoring means, with which the operating time t_operation can be monitored.

50. Surgical calibration device according to claim 46, wherein an operating time restriction device is provided to restrict the operating time t_operation to a maximum time in a range of 1 second to 60 minutes.

51. Surgical calibration device according to claim 28, wherein the calibration unit comprises at least one inertial sensor.

52. Surgical calibration device according to claim 28, wherein the calibration unit and the at least one referencing unit respectively comprise at least one transmitting unit for transmitting measured values or changes of the position and/or orientation data of the calibration unit and the at least one referencing unit to the navigation system or to a detection device thereof.

53. Surgical calibration device according to claim 28, wherein for determination of the position and/or orientation data of the calibration unit and of the at least one referencing unit, the navigation system comprises an evaluation unit, which is configured in such a manner that absolute position and/or orientation data can be calculated for the calibration unit and/or the at least one referencing unit from acceleration values measured by means of the at least one inertial sensor.

54. Surgical calibration device according to claim 53, wherein the evaluation unit is configured and/or programmed in such a manner that position and/or orientation change data of the calibration unit and the at least one referencing unit can be calculated from the measured acceleration values in relation to the coordinate system, and that absolute position and/or orientation data of the calibration unit and the at least one referencing unit can be calculated from the calculated position and/or orientation change data in relation to the coordinate system.

55. Surgical calibration device according to claim 28, wherein an inertial sensor unit comprising the at least one inertial sensor is provided, which comprises at least six acceleration sensors, with which accelerations acting on the calibration unit and/or the at least one referencing unit can be measured as a function of time in three mutually linearly independent directions and around three mutually linearly independent rotational axes.

56. Surgical calibration device according to claim 28, wherein at least one calibration gauge is provided, which has at least one calibration receiving means to at least partially receive the calibration unit in the calibration position.

57. Surgical calibration device according to claim 56, wherein the at least one calibration gauge is arranged on the at least one referencing unit.

58. Surgical calibration device according to claim 56, wherein at least one calibration receiving means comprises a recess, which corresponds to a part of the calibration unit and into which this one part of the calibration unit can be inserted in a positive arrangement.

59. Device according to claim 56, wherein the at least one calibration gauge is a one-, two- or three-dimensional calibration gauge for a position and/or orientation calibration of the at least one referencing unit and the calibration unit relative to one another.

60. Surgical calibration device according to claim 31, wherein the origin calibration gauge has at least one origin calibration receiving means for at least partially receiving the calibration unit in the origin calibration position.

61. Surgical calibration device according to claim 60, wherein the at least one origin calibration receiving means is a recess, which corresponds to a part of the calibration unit and into which the one part of the calibration unit can be inserted in a positive arrangement.

62. Surgical calibration device according to claim 34, wherein the origin calibration actuating element and/or the actuating element can be actuated manually.

63. Surgical calibration device according to claim 62, wherein the origin calibration actuating element and/or the actuating element comprise a microswitch arranged on the origin calibration gauge and/or on the at least one referencing unit or on the calibration gauge.