Automated robotic measuring system

• US 7,152,456 B2
• Filed: 01/14/2004
• Issued: 12/26/2006
• Est. Priority Date: 01/14/2004
• Status: Active Grant

• Current Assignee: Hexagon Metrology Incorporated (Hexagon AB)
• Original Assignee: Romer Incorporated (Hexagon AB)
• Inventors: Eaton, Homer
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): FITZGERALD, JOHN P
• Application Number:
  US10/758,697
• Publication Number:
  US 20050150123A1
• Time in Patent Office: 1,077 Days
• Field of Search: 73/17.9
• US Class Current: 73/1.79
• CPC Class Codes: G01B 5/004 for measuring coordinates of points
• CPC Class Codes: Y10T 74/20329 Joint between elements

Abstract

An automated coordinate measuring system comprising a measuring arm used for acquisition of geometry data that incorporates an exoskeletal structure resilient to physical perturbations including thermal changes and vibrations which may affect coordinate data acquisition. The system may be adapted to a portable platform allowing for convenient positioning and alignment of the measuring arm in a wide variety of environments.

Claims

1. A positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned on said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm; and

at least one alignment detector configured to detect the alignment between the articulated supporting arm and the articulated measuring arm.

2. The positioning system of claim 1 wherein, the articulated supporting arm and articulated measuring arm are aligned such that movement of the articulated supporting arm in a first direction effectuates movement of the articulated measuring arm in the same relative direction.

3. The positioning system of claim 1 wherein, the articulated supporting arm and articulated measuring arm are generally coaxially aligned.

4. The positioning system of claim 1 wherein, mechanical stress along the measuring arm is reduced by the support provided by the compliant members.

5. The positioning system of claim 1 wherein, the yielding characteristic of the compliant member is provided by a gas-filled chamber between the articulated supporting arm and the articulated measuring arm.

6. The positioning system of claim 1 wherein, the alignment detector comprises at least one strain gauge configured to measure deformation in the compliant members indicative of the relative alignment between the articulated supporting arm and the articulated measuring arm.

7. The positioning system of claim 1 wherein, the alignment detector comprises at least one pressure sensor configured to measure deformation in the compliant members indicative of the relative alignment between the articulated supporting arm and the articulated measuring arm.

8. The positioning system of claim 1 wherein, the articulated supporting arm at least partially isolates the articulated measuring arm from physical perturbations.

9. The positioning system of claim 1 wherein, the articulated supporting arm at least partially thermally isolates the articulated measuring arm.

10. The positioning system of claim 1 wherein, the articulated supporting arm defines a space in which the compliant members at least partially reside and provide a constrained range of alignment between the articulated supporting arm and the articulated measuring arm.

11. The positioning system of claim 1 wherein, the compliant members dampen vibrations transmitted to the articulated measuring arm.

12. The positioning system of claim 1, further comprising:

a probe member attached to said articulated measuring arm and positioned in three dimensional space by the articulated measuring arm.

13. The positioning system of claim 12 wherein, the probe member comprises a coordinate measuring component for acquiring geometry information.

14. The positioning system of claim 12 wherein, the probe member comprises a tool to be accurately positioned in three dimensional space.

15. The positioning system of claim 12 wherein, the probe member comprises an instrument to be accurately positioned in three dimensional space.

16. The positioning system of claim 1 wherein, the support arm segments of the articulated supporting arm are shaped so as to at least partially contain the measuring arm segments of the articulated measuring arm.

17. The positioning system of claim 16 wherein, the plurality of compliant members position and support the measuring arm segments of the articulated measuring arm within the support arm segments of the articulated supporting arm.

18. The positioning system of claim 1 wherein, the yielding characteristic of the compliant members permit a degree of angular offset between the articulated supporting arm and articulated measuring arm.

19. The positioning system of claim 18 wherein, angular offset between the articulated supporting arm and articulated measuring arm is effectuated by stress applied to either the articulated supporting arm or the articulated measuring arm.

20. The positioning system of claim 1 wherein, the compliant members are formed from an at least partially deformable material.

21. The positioning system of claim 20 wherein, the deformable material comprises a material selected from the group consisting of:

rubber, plastic, nylon, foam, metal, and spring materials.

22. The positioning system of claim 1 further comprising:

a controller configured to direct the positioning of the articulated supporting arm.

23. The positioning system of claim 22 wherein, the controller directs positioning of the articulated supporting arm with respect to the articulated measuring arm to reduce the relative degree of angular deflection between the arms.

24. The positioning system of claim 22 wherein, the controller receives information from a first and second encoder and determines the alignment of the articulated supporting arm with respect to the articulated measuring arm on the basis of the received information.

25. The positioning system of claim 22 wherein, the controller directs positioning of the articulated supporting arm to provide assisted movement of the articulated measuring when an exerted force is applied to the articulated measuring arm.

26. The positioning system of claim 22 wherein, the controller directs positioning of the articulated supporting arm to resist movement of the articulated measuring arm when a force is applied to the articulated measuring arm.

27. The positioning system of claim 22 wherein, the controller directs positioning of the articulated supporting arm to resist movement of the articulated measuring arm when a torque is applied to the articulated measuring arm.

28. The positioning system of claim 22 wherein, the controller directs characteristics selected from the group consisting of:

speed, direction, and distance for positioning of the articulated supporting arm based upon the detected alignment between the articulated supporting arm and the articulated measuring arm.

29. The positioning system of claim 28 wherein, the characteristics of the articulated supporting arm positioning are generally proportional to a detected change in alignment between the articulated measuring arm member and the articulated supporting arm.

30. An accurate positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned about said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm;

a controller configured to direct positioning of the articulated supporting arm; and

a datastore containing information that is accessible by the controller and used to resolve the alignment of the articulated supporting arm with respect to the articulated measuring arm.

31. The positioning system of claim 30 wherein, at least one strain gauge is configured to detect stress applied to selected compliant members, the detected stress used by the controller to direct positioning of the articulated supporting arm.

32. The positioning system of claim 30 wherein, at least one pressure sensor is configured to detect stress applied to selected compliant members, the detected stress used by the controller to direct positioning of the articulated supporting arm.

33. The positioning system of claim 30 wherein, the complaint members are formed from an at least partially deformable material and at least one alignment detector measures force applied to the at least one compliant member based on the degree of deformation of the compliant member.

34. The positioning system of claim 30 wherein, the complaint members are formed from an at least partially deformable material and at least one alignment detector measures torque applied to the at least one compliant member based on the degree of deformation of the compliant member.

35. The positioning system of claim 30 wherein, the controller selectively positions the articulated measuring arm by determining appropriate angular deflections of the articulated positioning arm based upon the information contained in the datastore.

36. The positioning system of claim 30 wherein, the datastore is developed by directing positioning of the articulated positioning arm in a plurality of orientations and associating each position with information characterizing the angular deflections of the articulated positioning arm member and the articulated measuring arm.

37. The positioning system of claim 30 wherein, development of the datastore is performed using a training program that contains a plurality pre-determined instructions used to direct positioning of the articulated positioning arm.

38. The positioning system of claim 30 wherein, the controller directs positioning of the articulated supporting arm by issuing instructions to at least one actuator specifying angular deflections for which to drive positioning of the articulated positioning arm.

39. The positioning system of claim 30 wherein, the datastore comprises angular deflections of the articulated positioning arm and the articulated measuring arm achieved by various positionings in three dimensional space.

40. The positioning system of claim 30 wherein, the controller determines a driving load used to position the articulated positioning arm based at least in part upon the information contained in the datastore.

41. The positioning system of claim 30 wherein, the controller determines the magnitude of a driving load to position the articulated positioning arm based in part upon a detected magnitude of applied load.

42. The positioning system of claim 30 further comprising:

at least one alignment detector configured to generate alignment information characterizing the alignment of the articulated supporting arm and the alignment of the articulated measuring arm and further configured to provide the alignment information to the controller.

43. The positioning system of claim 42 wherein, the controller determines the alignment of the articulated supporting arm with respect to the articulated measuring arm by comparing the alignment information with previously determined alignment information contained in the datastore.

44. The positioning system of claim 30 wherein, the controller resolves the position of the articulated positioning arm with respect to the articulated measuring arm based upon their respective angular deflections.

45. The positioning system of claim 44 wherein, the angular deflections are determined in part by the yielding characteristic of the compliant members between the articulated supporting arm and the articulated measuring arm.

46. The positioning system of claim 30 wherein, the datastore comprises a plurality of alignment detector values associated with selected angular deflections of the articulated positioning arm and the articulated measuring arm defining various positionings.

47. The positioning system of claim 46 wherein, the controller discerns the relative position of the articulated measuring arm by comparing alignment detector values associated with a current positioning of the articulated supporting arm with information contained in the datastore that has been previously associated selected positions of the articulated supporting arm.

48. The positioning system of claim 30 further comprising:

a probe member attached to said articulated measuring arm and positioned in three dimensional space by the articulated measuring arm.

49. The positioning system of claim 48 wherein, the probe member comprises a tool to be accurately positioned in three dimensional space.

50. The positioning system of claim 48 wherein, the probe member comprises an instrument to be accurately positioned in three dimensional space.

51. The positioning system of claim 48 wherein, the probe member comprises a coordinate acquisition device for acquiring geometry information and wherein positioning of the coordinate acquisition device is directed at least in part by the controller that directs positioning the articulated positioning member which in turn effectuates positioning of the articulated measuring arm through the compliant members.

52. The positioning system of claim 48 wherein, the controller provides instructions to at least one actuator to effectuate desired angular deflections of the articulated positioning arm with respect to the articulated measuring arm to achieve a selected positioning of the probe member in three dimensional space.

53. The positioning system of claim 30 wherein, the datastore is generated by the steps of:

identifying a plurality of controller instructions to direct positioning of the articulated positioning arm in a plurality of orientations;

measuring the resulting position of the articulated measuring arm arising from each controller instruction; and

associating and storing the instructions and the resulting positionings.

54. The positioning system of claim 53 wherein, once the datastore has been developed its contents are copied to other positioning systems.

55. The positioning system of claim 54 wherein, copying of the datastore to other coordinate measuring systems provides a means clone the positioning characteristics of the articulated positioning arm and articulated measuring arm without having to substantially regenerate the datastore.

56. The positioning system of claim 30 wherein, the controller directs power-assisted manual positioning of the articulated positioning arm.

57. The positioning system of claim 56 wherein, the power-assisted manual positioning of the articulated positioning arm is achieved by the controller detecting manually applied loads and directing positioning of the articulated positioning arm in the direction of the applied load.

58. The positioning system of claim 57 wherein, manually applied loads to the articulated measuring arm result in changes in the yielding characteristics of the compliant members and are detected by the controller.

59. The positioning system of claim 58 wherein, the controller ascertains the magnitude of the applied load based upon changes in the yielding characteristics of the compliant members.

60. A positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned on said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm; and

a controller configured to direct the positioning of the articulated supporting arm;

wherein, the controller directs positioning of the articulated supporting arm with respect to the articulated measuring arm to reduce the relative degree of angular deflection between the arms.

61. A positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned on said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm; and

a controller configured to direct the positioning of the articulated supporting arm;

wherein, the controller receives information from a first and second encoder and determines the alignment of the articulated supporting arm with respect to the articulated measuring arm on the basis of the received information.

62. A positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned on said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm; and

a controller configured to direct the positioning of the articulated supporting arm;

wherein, the controller directs positioning of the articulated supporting arm to provide assisted movement of the articulated measuring when an exerted force is applied to the articulated measuring arm.

63. A positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned on said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm; and

a controller configured to direct the positioning of the articulated supporting arm;

wherein, the controller directs positioning of the articulated supporting arm to resist movement of the articulated measuring arm when a force is applied to the articulated measuring arm.

64. A positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned on said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm; and

a controller configured to direct the positioning of the articulated supporting arm;

wherein, the controller directs positioning of the articulated supporting arm to resist movement of the articulated measuring arm when a torque is applied to the articulated measuring arm.

65. A positioning system comprising:

an articulated supporting arm comprising a plurality of jointedly interconnected support arm segments moveable about a plurality of axes;

a plurality of compliant members positioned on said supporting arm;

an articulated measuring arm comprising a plurality of jointedly interconnected measuring arm segments capable of a plurality of degrees of freedom of movement and supported by said compliant members wherein said compliant members provide a yielding characteristic between the articulated supporting arm and the articulated measuring arm; and

a controller configured to direct the positioning of the articulated supporting arm;

wherein, the controller directs characteristics selected from the group consisting of;

speed, direction, and distance for positioning of the articulated supporting arm based upon the detected alignment between the articulated supporting arm and the articulated measuring arm.

66. The positioning system of claim 65 wherein, the characteristics of the articulated supporting arm positioning are generally proportional to a detected change in alignment between the articulated measuring arm member and the articulated supporting arm.