MULTIPLE AXIS GIMBAL EMPLOYING NESTED SPHERICAL SHELLS

• US 20100019120A1
• Filed: 12/13/2005
• Published: 01/28/2010
• Est. Priority Date: 12/13/2004
• Status: Active Grant

• Current Assignee: Optical Alchemy, Inc.
• Original Assignee: Optical Alchemy, Inc.
• Inventors: Burnham, Heidi, Daigle, Marc
• Granted Patent: US 7,905,463 B2
• Time in Patent Office: Days
• US Class Current: 248/550
• CPC Class Codes: F16M 11/123 the axis of rotation intersecting in a single point, e.g. by using gimbals
• CPC Class Codes: F16M 11/18 with mechanism for moving the apparatus relatively to the stand
• CPC Class Codes: F41A 27/14 Central-pivot bearings
• CPC Class Codes: F41G 3/22 for vehicle-borne armament, e.g. on aircraft
• CPC Class Codes: Y10T 74/1221 Multiple gyroscopes

Abstract

A multi-axis gimbal has each axis defined by a respective spherical shell driven by a flat, compact motor attached to the driven shell and to a next outer shell (or to an external mounting platform, in the case of the outermost shell). The shells rotate about respective axes. In one configuration, the outermost shell is referred to as the “azimuth” shell because in use it rotates about a vertical axis. The next inner shell is an elevation shell that rotates about a first horizontal axis that is orthogonal to the axis of the camera or other sensor payload. An optional third shell can be used to provide “roll” motion, such as rotating a camera about its axis to obtain a particular rotational orientation with respect to a target.

Claims

1. A gimbal for controlling the orientation of a sensor payload to be carried by the gimbal, comprising:

a substantially spherical first shell configured for rotation about a first axis; and

a payload support structure disposed within and rotatably coupled to the first shell, the payload support structure being configured for rotation about a second axis with respect to the first shell, the second axis being orthogonal to the first axis.

2. A gimbal according to claim 1, wherein the first shell is an outermost shell of the gimbal.

3. A gimbal according to claim 1, further comprising a second shell in which the first shell is rotatably disposed, the second shell being rotatable about a third axis orthogonal to both the first and second axes.

4. A gimbal according to claim 1, wherein the payload support structure is rotatably coupled to the first shell by a direct-drive motor.

5. A gimbal according to claim 1, wherein the first shell is substantially completely enclosed and includes a portion transparent to electromagnetic energy being sensed by a sensor payload mounted on the payload support structure.

6. A gimbal according to claim 5, wherein the electromagnetic energy being sensed by the sensor payload includes electromagnetic energy in the visible light spectrum.

7. A gimbal according to claim 1, wherein the first shell comprises two half-shells joined together.

8. A gimbal according to claim 7, wherein the two half-shells are joined by lap joints.

9. A gimbal according to claim 1, wherein the first shell includes an opening for passage of electromagnetic energy being sensed by a sensor payload mounted on the payload support structure.

10. A gimbal according to claim 9, wherein the opening comprises an elongated slot extending partway around the first shell.

11. A gimbal according to claim 10, wherein the elongated slot extends approximately 90 degrees around the first shell.

12. A gimbal according to claim 1, wherein the first shell includes a ribbed or pocketed structure to reduce weight and increase stiffness.

13. A gimbal according to claim 1, further comprising a gimbal drive mechanism.

14. A gimbal according to claim 13, wherein the gimbal drive mechanism is a harmonic drive mechanism.

15. A gimbal according to claim 13, wherein the gimbal drive mechanism is a harmonic drive mechanism.

16. A gimbal according to claim 13, wherein the gimbal drive mechanism is a belt drive mechanism.

17. A gimbal according to claim 13, wherein the gimbal drive mechanism is a gear drive mechanism.

18. A gimbal according to claim 13, wherein the gimbal drive mechanism is a viscous coupling mechanism.

19. A gimbal according to claim 1, further comprising a position encoder for providing motor position information to a gimbal controller.

20. A gimbal according to claim 19, wherein the position encoder comprises an inductosyn encoder.

21. A gimbal according to claim 19, wherein the position encoder comprises an optical encoder using the Talbot effect.

22. A gimbal according to claim 19, wherein the position encoder comprises an optical encoder using a transmission grating.

23. A gimbal according to claim 1, wherein the payload support structure is a substantially spherical second shell.

24. A gimbal according to claim 23, further comprising an air bearing and low-friction support pads between the first and second shells.

25. A gimbal according to claim 23, further comprising linear motors within the first and second shells.

26. A gimbal according to claim 23, further comprising momentum reaction wheels to adjust gimbal attitude.

27. A gimbal according to claim 23, further comprising high-surface-tension fluid bearings between the first and second shells.

28. A gimbal according to claim 1, wherein the first shell comprises an integral wire channel to hold signal cables.

29. A gimbal according to claim 28, wherein the integral wire channel comprises a depression in the first shell.

30. A gimbal according to claim 1, further comprising a drive assembly including a rotary joint twist capsule for conduction of signals.

31. A gimbal according to claim 1, further comprising a payload operative to pass payload signals optically through a transparent portion of the first shell.

32. A gimbal according to claim 1, further comprising a payload operative to pass payload signals wirelessly via a transceiver across the first shell to an external electronic transceiver.

33. A gimbal according to claim 1, further comprising an inertial reference measurement unit (IRMU) on the payload support structure for inertial stabilization.

34. A gimbal according to claim 33, wherein the IRMU comprises a selected one of (MEMS based, FOG based, mechanical based, integrated optics based, and laser ring gyro based).

35. A gimbal according to claim 1 employing an inertial control design that includes at least one of (linear multivariable techniques, and nonlinear techniques).

36. A gimbal according to claim 35, wherein the linear multivariable techniques are selected from the group consisting of (H-Infinity, H-2, Mu-Synthesis, Loop-Transfer Recovery (“

LTR”

), and individual channel design (“

ICD”

)).

37. A gimbal according to claim 35, wherein the nonlinear techniques are selected from the group consisting of (inverse kinematic control, feedback linearization, and sliding mode control).

38. A gimbal according to claim 1, further comprising a slip ring between the first shell and the payload structure to pass signals therebetween.

39. A gimbal according to claim 1, further comprising components of inertial reference measurement unit distributed within the gimbal.

40. A gimbal according to claim 5, wherein the transparent portion is substantially continuous.

41. A gimbal according to claim 5, wherein the transparent portion is segmented.