Precision cable drive

• US 6,503,163 B1
• Filed: 12/20/1999
• Issued: 01/07/2003
• Est. Priority Date: 05/15/1996
• Status: Expired due to Term

• Current Assignee: Sensar, Inc. (Advent International Corporation)
• Original Assignee: Sensar, Inc. (Advent International Corporation)
• Inventors: Spangler, Joseph Freeman III, Killion, Christopher John, Van Sant, Glen
• Primary Examiner(s): Bucci, David A.
• Assistant Examiner(s): Johnson, Vicky A.
• Application Number:
  US09/467,625
• Time in Patent Office: 1,114 Days
• Field of Search: 474/64, 474/65, 474/68, 474/87, 474/89, 474/101, 474/117, 74/107, 74/892.2, 242/481.4
• US Class Current: 474/101
• CPC Class Codes: G02B 26/0816 by means of one or more reflecting elements
• CPC Class Codes: G02B 26/10 Scanning systems
• CPC Class Codes: G06V 40/19 Sensors therefor
• CPC Class Codes: G07C 9/37 using biometric data, e.g. fingerprints, iris scans or voice recognition
• CPC Class Codes: G07F 19/20 Automatic teller machines [ATMs]
• CPC Class Codes: G07F 19/207 Surveillance aspects at ATMs
• CPC Class Codes: H04N 13/207 using a single 2D image sensor
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/246 Calibration of cameras
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 2013/0081 Depth or disparity estimation from stereoscopic image signals
• CPC Class Codes: H04N 23/50 Constructional details
• CPC Class Codes: H04N 23/56 provided with illuminating means

Abstract

The precision cable drive system of the present invention consists generally of a frame upon which is mounted the components of the drive. These include a motor having a drive shaft, a plurality of idler pulleys, a tensioner, and a drive pulley, to which the object being rotated is connected. A cable composed of woven polymer fibers is wrapped around the shaft of the motor and is stretched around the idler pulleys, the tensioner and the drive pulley. The drive is capable of rotating the drive pulley, and the load attached to it, by fractions of a degree, without play between the motor shaft and the drive pulley. The drives are used in a compact image steering device to rotate cameras and illuminators about two axis of rotation.

Claims

1. A drive system for providing precise rotational motion comprising:

a. a rigid frame defining a hole therein;

b. a servo motor having a shaft, said motor attached to said frame such that said shaft protrudes through said hole defined in said frame and the motor being controlled by a feedback control system that utilizes at least one incremental encoder;

c. a first idler pulley, mounted on said frame adjacent said shaft of said motor;

d. a second idler pulley, mounted on said frame adjacent said shaft of said motor, opposite said first idler pulley, wherein said first pulley, said second pulley, and said shaft are spatially arranged so as to be tangentially aligned along a straight line;

e. a drive pulley, disposed such that said drive pulley rotates less than 360 degrees in either direction;

f. a cable, arranged in a path around said drive pulley, said first and second idler pulleys and said motor shaft, such that a rotation of said motor shaft will cause said drive pulley to rotate, said cable having two ends and wherein both of said ends of said cable are attached to said drive pulley;

g. a tensioner, arranged at a point along said path between one of said first and second idler pulleys and said drive pulley, for providing tension to said cable; and

h. a post, attached perpendicularly to said drive pulley, wherein both of said ends of said cable are attached to said post.

2. The drive system of claim 1 wherein said cable is composed of a polymer.

3. The drive system of claim 2 wherein said polymer has an elongation less than or equal to 5 percent.

4. The drive system of claim 2 wherein said polymer has a density of at least 0.95 grams per cubic centimeter.

5. The drive system of claim 2 wherein said polymer is configured as fibers and wherein said cable is composed of a plurality of said polymer fibers woven together.

6. The drive system of claim 2 wherein said polymer is polyethylene.

7. The drive system of claim 1 wherein said cable makes at least two full revolutions around said shaft.

8. The drive system of claim 1 wherein said tensioner is a pulley.

9. The drive system of claim 8 wherein said tensioner maintains a constant tension on said cable.

10. The drive system of claim 9 wherein said tension on said cable is adjustable.

11. The drive system of claim 9 wherein the longitudinal axis of said idler pulleys is held in a perpendicular relationship to said frame by one or more bearings when said tension is applied by said tensioner.

12. The drive system of claim 1 wherein no radial force is exerted on said shaft due to said tension applied by said tensioner.

13. The drive system of claim 1 wherein said ends of said cable are attached to said post by tying said ends of said cable to said post.

14. The drive system of claim 13 wherein said ends of said cable are tied to said post using an overhand loop knot.

15. The drive system of claim 1 wherein the ratio of shaft rotations to drive pulley rotations is approximately ten to 1.

16. The drive system of claim of claim 1 wherein said cable is arranged around the circumference of said drive pulley, further comprising at least one barb, extending from said circumference of said drive pulley, for keeping said cable aligned along said circumference thereof.

17. The drive system of claim 1 wherein said drive pulley is mounted on said frame.

18. The drive system of claim 1 wherein said frame is composed of aluminum.

19. The drive system of claim 1 wherein said frame is composed of plastic.

20. The drive system of claim 1 wherein said motor is a stepper motor.

21. The drive system of claim 1, wherein said drive pulley can be moved a minimum of one tenth of one degree.

22. A drive system for providing precise rotational motion comprising:

a. a rigid frame defining a hole therein;

b. a servo motor having a shaft, said motor attached to said frame such that said shaft protrudes through said hole defined in said frame and the motor being controlled by a feedback control system that utilizes at least one incremental encoder;

c. a first idler pulley, mounted on said frame adjacent said shaft of said motor;

d. a second idler pulley, mounted on said frame adjacent said shaft of said motor, opposite said first idler pulley, wherein said first pulley, said second pulley, and said shaft are spatially arranged so as to be tangentially aligned along a straight line;

e. a drive pulley, disposed such that said drive pulley rotates less than 360 degrees in either direction and wherein the ratio of shaft rotations to drive pulley rotations is approximately ten to one;

f. a cable, arranged in a path around said drive pulley, said first and second idler pulleys and said motor shaft, such that a rotation of said motor shaft will cause said drive pulley to rotate; and

g. a tensioner, arranged at a point along said path between one of said first and second idler pulleys and said drive pulley, for providing tension to said cable.

23. The drive system of claim 22 wherein said cable is composed of a polymer.

24. The drive system of claim 23 wherein said polymer has an elongation less than or equal to 5 percent.

25. The drive system of claim 23 wherein said polymer has a density of at least 0.95 grams per cubic centimeter.

26. The drive system of claim 23 wherein said polymer is configured as fibers and wherein said cable is composed of a plurality of said polymer fibers woven together.

27. The drive system of claim 23 wherein said polymer is polyethylene.

28. The drive system of claim 22 wherein said cable makes at least two full revolutions around said shaft.

29. The drive system of claim 22 wherein said tensioner is a pulley.

30. The drive system of claim 24 wherein said tensioner maintains a constant tension on said cable.

31. The drive system of claim 30 wherein said tension on said cable is adjustable.

32. The drive system of claim 30 wherein the longitudinal axis of said idler pulleys is held in a perpendicular relationship to said frame by one or more bearings when said tension is applied by said tensioner.

33. The drive system of claim 22 wherein no radial force is exerted on said shaft due to said tension applied by said tensioner.

34. The drive system of claim 22 where said cable has two ends and wherein both of said ends of said cable are attached to said drive pulley.

35. The drive system of claim 34 further comprising a post, attached perpendicularly to said drive pulley, wherein both of said ends of said cable are attached to said post.

36. The drive system of claim 35 wherein said ends of said cable are attached to said post by tying of said ends of said cable to said post.

37. The drive of claim 36 wherein said ends of said cable are tied to said post using an overhand loop knot.

38. The drive system of claim 34 wherein said cable is arranged around the circumference of said drive pulley, further comprising at least one barb, extending from said circumference of said drive pulley, for keeping said cable aligned along said circumference thereof.

39. The drive system of claim 22 wherein said drive pulley is mounted on said frame.

40. The drive system of claim 22 wherein said frame is composed of aluminum.

41. The drive system of claim 22 wherein said frame is composed of plastic.

42. The drive system of claim 22 wherein said motor is a stepper motor.

43. The drive system of claim 22 wherein said drive pulley can be moved a minimum of one tenth of one degree.

46. The drive system of claim 25 wherein said polymer has an elongation less than or equal to 5 percent.

44. A drive system for providing precise rotational motion comprising:

a. a rigid frame defining a hole therein;

b. a servo motor having a shaft, said motor attached to said frame such that said shaft protrudes through said hole defined in said frame and the motor being controlled by a feedback control system that utilizes at least one incremental encoder;

c. a first idler pulley, mounted on said frame adjacent said shaft of said motor;

d. a second idler pulley, mounted on said frame adjacent said shaft of said motor, opposite said first idler pulley, wherein said first pulley, said second pulley, and said shaft are spatially arranged so as to be tangentially aligned along a straight line;

e. a drive pulley, disposed such that said drive pulley rotates less than 360 degrees in either direction;

f a cable, arranged in a path around said drive pulley, said first and second idler pulleys and said motor shaft, such that a rotation of said motor shaft will cause said drive pulley to rotate, said cable having two ends and wherein both of said ends of said cable are attached to said drive pulley, further wherein said cable is arranged around the circumference of said drive pulley, further comprising at least one barb, extending from said circumference of said drive pulley, for keeping said cable aligned along said circumference thereof; and

g. a tensioner, arranged at a point along said path between one of said first and second idler pulleys and said drive pulley, for providing tension to said cable.

45. The drive system of claim 44 wherein said cable is composed of a polymer.

47. The drive system of claim 45 wherein said polymer has a density of at least 0.95 grams per cubic centimeter.

48. The drive system of claim 45 wherein said polymer is configured as fibers and wherein said cable is composed of a plurality of said polymer fibers woven together.

49. The drive system of claim 45 wherein said polymer is polyethylene.

50. The drive system of claim 44 wherein said cable makes at least two full revolutions around said shaft.

51. The drive system of claim 44 wherein said tensioner is a pulley.

52. The drive system of claim 51 wherein said tensioner maintains a constant tension on said cable.

53. The drive system of claim 52 wherein said tension on said cable is adjustable.

54. The drive system of claim 53 wherein the longitudinal axis of said idler pulleys is held in a perpendicular relationship to said frame by one or more bearings when said tension is applied by said tensioner.

55. The drive system of claim 44 wherein no radial force is exerted on said shaft due to said tension applied by said tensioner.

56. The drive system of claim 44 further comprising a post, attached perpendicularly to said drive pulley, wherein both of said ends of said cable are attached to said post.

57. The drive system of claim 44 wherein said ends of said cable are attached to said post by tying of said ends of said cable to said post.

58. The drive of claim 57 wherein said ends of said cable are tied to said post using an overhand loop knot.

59. The drive system of claim 44 wherein the ratio of shaft rotations to drive pulley rotations is approximately ten to 1.

60. The drive system of claim 44 wherein said drive pulley is mounted on said frame.

61. The drive system of claim 44 wherein said frame is composed of aluminum.

62. The drive system of claim 44 wherein said frame is composed of plastic.

63. The drive system of claim 44 wherein said motor is a stepper motor.

64. The drive system of claim 44 wherein said drive pulley can be moved a minimum of one tenth of one degree.