Force reflecting haptic interface

• US 6,985,133 B1
• Filed: 07/16/1999
• Issued: 01/10/2006
• Est. Priority Date: 07/17/1998
• Status: Expired due to Term

• Current Assignee: 3D Systems, Inc. (3D Systems Corporation)
• Original Assignee: SensAble Technologies, Inc. (3D Systems Corporation)
• Inventors: Massie, Thomas H., Ziegler, Andrew, Bolton, Clive, Rodomista, Guy, Lohse, R. Michael, Goodwin, William A.
• Primary Examiner(s): Chow, Dennis-Doon
• Application Number:
  US09/356,289
• Time in Patent Office: 2,370 Days
• Field of Search: 345/156, 345/161, 345/157, 345/578, 364/578
• US Class Current: 345/156
• CPC Class Codes: G06F 3/016 Input arrangements with force or tactile feedback as computer generated output to the user

Abstract

A six degree of freedom force reflecting haptic interface includes three powered axes and three free axes, all of which are tracked so that the position of a user connection element in the work volume can be determined. The interface includes cable drives with polymer composite or metallic cables, automatic cable tensioning devices, and grounded actuator capstans. A nested hub and transfer drive provide a compact, weight balanced interface. User comfort and safety features are also provided.

Claims

1. A force reflecting haptic interface includes a housing and at least three structural elements connected by at least three articulations, the interface comprising:

a first rotary element supported by the housing and defining a first articulation;

a second rotary element mounted to the first rotary element and defining a second articulation;

a third rotary element mounted on a radially disposed extension of the second rotary element and defining a third articulation; and

an actuator and a tungsten cable to power at least one of the rotary elements.

2. The force reflecting haptic interface of claim 1 further comprising:

a second articulation hub; and

a transfer drive for powering the third articulation, wherein the second articulation hub and the transfer drive are coaxially nested on a common axis.

3. The force reflecting haptic interface of claim 2, wherein the transfer drive comprises:

a transfer drive element;

a first transfer drive rod coupled to the transfer drive element and the third rotary element; and

a second transfer drive rod coupled to the transfer drive element and the third rotary element.

4. The force reflecting haptic interface of claim 3, wherein the first transfer drive rod is directly coupled to the transfer drive element and the third rotary element via looped drive cables, and the second transfer drive rod is directly coupled to the third rotary element via a looped drive cable and indirectly coupled to the transfer drive element via a looped drive cable coupled to a clutch post and a spring.

5. The haptic interface of claim 1 further comprising:

a drive for transmitting forces to a user and for receiving forces from a user, the drive comprising;

an actuator;

a capstan mounted to the actuator; and

a tungsten cable coupled to the capstan.

6. The haptic interface of claim 5, wherein the cable has a nominal diameter of about 0.015 inches.

7. The haptic interface of claim 5, wherein the cable is swaged.

8. The haptic interface of claim 5, wherein the cable construction is 8×

19 class, the 8×

19 class comprising a 7×

7 core wrapped by eight 1×

19 filament strands.

9. The haptic interface of claim 5, wherein an encoder is disposed on the actuator proximate the capstan.

10. The haptic interface of claim 9, wherein the encoder is an optical encoder.

11. The haptic interface of claim 9, further comprising a collar for mounting the encoder on a shaft of the actuator.

12. The haptic interface of claim 9, wherein the encoder comprises an encoder disk and an emitter/detector pair disposed at an edge of the encoder disk.

13. The haptic interface of claim 1 further comprising:

a drive for transmitting forces to a user and for receiving forces from a user, the drive comprising;

an actuator;

a capstan mounted to the actuator; and

a stranded cable coupled to the capstan, wherein each strand has a nominal diameter less than about 0.001 inches.

14. The force reflecting haptic interface of claim 1 further comprising:

a fourth rotary element mounted on a radially disposed extension of the third rotary element and defining a fourth articulation;

a fifth rotary element mounted on a radially disposed extension of the fourth rotary element and defining a fifth articulation; and

a sixth rotary element mounted on a radially disposed extension of the fifth rotary element and defining a sixth articulation.

15. The force reflecting haptic interface of claim 1, wherein the housing is not attached to a grounded surface.

16. An automatic cable tensioning device for a haptic interface, the automatic cable tensioning device comprising:

a cable including a proximate end fixed directly to a ground surface and a distal end fixed indirectly to the ground surface;

a clutch post fixed to the ground surface along a cable path;

a spring disposed between the distal cable end and the ground surface; and

an actuator capstan disposed along the cable path, wherein the cable extends from the ground surface, circumscribes the actuator capstan and then the clutch post at least once each before being coupled to the spring, which is in tension.

17. The automatic cable tensioning device of claim 16, wherein the clutch post is non-rotating.

18. The automatic cable tensioning device of claim 16, wherein the clutch post amplifies the applied cable tension of the spring.

19. The automatic cable tensioning device of claim 16, wherein the ground surface is a generally circular hub of an axis drive element.

20. The automatic cable tensioning device of claim 19, wherein the actuator capstan is disposed substantially tangentially to the circular hub.

21. A grounded capstan for use in a haptic interface, the grounded capstan comprising:

a substantially cylindrical exterior surface and a longitudinal axis, the capstan defining a bore substantially parallel to the longitudinal axis for receiving an actuator shaft such that a gap is formed between the shaft and the capstan to accommodate a portion of the drive cable; and

a generally radially disposed aperture defied by the capstan, the aperture being substantially perpendicular to the longitudinal axis, wherein the aperture is sized to permit passage therethrough of a double portion of the drive cable, such that the drive cable is captured in the bore.

22. The grounded capstan of claim 21, wherein the capstan includes a helical channel formed along the exterior surface of the capstan.

23. The grounded capstan of claim 21 further comprising an actuator shaft disposed in the bore, wherein the capstan is mechanically secured to the shaft.

24. The grounded capstan of claim 21 further comprising an actuator shaft disposed in the bore, wherein the capstan is bonded to the shaft.

25. The grounded capstan of claim 21 further comprising an actuator shaft disposed in the bore, wherein the capstan and the shaft include an anti-rotation feature for securing the shaft against rotation relative the capstan.

26. The grounded capstan of claim 21, wherein the capstan defines a groove perpendicular to the circumference of the bore, the groove sized to accommodate the double portion of the drive cable.

27. A composite cable for a haptic interface, the composite cable comprising a fused blend of:

(i) a high modulus polyethlene material; and

(ii) a liquid crystal aromatic polyester-polyarylate material, wherein the cable comprises about 20–

80 percent high modulus polyethylene material and about 80–

20 percent liquid crystal aromatic polyester-polyarylate material.

28. A composite cable for a haptic interface, the composite cable comprising a fused blend of:

(i) a high modulus polyethylene material; and

(ii) a liquid crystal aromatic polyester-polyarylate material, wherein the cable comprises about 30–

70 percent high modulus polyethylene material and about 70–

30 percent liquid crystal aromatic polyester-polyarylate material.

29. A composite cable for a haptic interface, the composite cable comprising a fused blend of:

(i) a high modulus polyethylene material; and

(ii) a liquid crystal aromatic polyester-polyarylate material, wherein the cable comprises about 40–

60 percent high modulus polyethylene material and about 60–

40 percent liquid crystal aromatic polyester-polyarylate material.