Suspension system for gimbal supported scanning payloads

• US 5,396,815 A
• Filed: 09/15/1993
• Issued: 03/14/1995
• Est. Priority Date: 09/15/1993
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration
• Inventors: Alhorn, Dean C., Polites, Michael E.
• Primary Examiner(s): Herrmann, Allan D.
• Application Number:
  US08/123,629
• Time in Patent Office: 545 Days
• Field of Search: 74/61, 74/87, 244/158 R, 343/765, 343/766
• US Class Current: 74/61
• CPC Class Codes: B64G 1/22 Parts of, or equipment specially adapted for fitting in or to, cosmonautic vehicles
• CPC Class Codes: B64G 1/24 Guiding or controlling apparatus, e.g. for attitude control
• CPC Class Codes: B64G 1/28 using inertia or gyro effect
• CPC Class Codes: B64G 1/283 using reaction wheels
• CPC Class Codes: B64G 1/285 using momentum wheels
• CPC Class Codes: B64G 1/286 using control momentum gyroscopes (CMGs)
• CPC Class Codes: B64G 1/32 using earth's magnetic field
• CPC Class Codes: B64G 1/36 using sensors, e.g. sun-sensors, horizon sensors
• CPC Class Codes: B64G 1/361 using star sensors
• CPC Class Codes: B64G 1/363 using sun sensors
• CPC Class Codes: B64G 1/369 using gyroscopes as attitude sensors
• CPC Class Codes: F16H 33/20 for interconversion, based essentially on inertia, of rotary motion and reciprocating or oscillating motion for converting into a linear propulsion force, i.e. inertia motors F03G3/00
• CPC Class Codes: Y10T 74/18344 Unbalanced weights
• CPC Class Codes: Y10T 74/18552 Unbalanced weight

Abstract

Gimballed scanning devices are an important aspect of space science. To achieve a scan pattern some means must be provided which impart to the devices an oscillatory motion. Various forms of machines have been employed for controllably conferring scan patterns on these scanning devices. Although they have included control moment gyroscopes, reaction wheels, torque motors, reaction control systems, and the like, rotating unbalanced mass (RUM) devices are a new and more efficient way to generate scans in gimballed devices or payloads. But they require power consuming and frequently complex auxiliary control systems to position and reposition the particular scan pattern relative to a target or a number of targets. Herein the control system is simplified. In the suspension system provided for payloads rotatably supported in gimbals payload rotation is restricted by a flex pivot so that the payload oscillates, moving in a scan pattern.

Claims

1. Suspension means for payloads rotatably supported in gimbals wherein payload rotation is restricted so that the payload moves in a scan pattern, comprising a gimbal, a payload to be supported in the gimbal, a first axle means having one end attached to one side of the payload and its other end attached to the gimbal, a second axle means having one end attached to the gimbal, and its other end attached to the other side of the payload, the first axle means having one of its ends journaled to permit payload rotation, the second axle means being a flex pivot, flexible about a torsional moment, but inflexible about bending moments to restrict said rotation, drive means effecting rotation of the payload, the rotation of the payload being limited by the torsional spring constant of the flex pivot so that the drive means imparts only an oscillatory motion to the payload to effect its scan pattern, positioning means coupled with the flex pivot, the positioning means being adapted to hold the flex pivot in a fixed position and to turn the flex pivot when the positioning means are actuated.

2. The suspension means of claim 1 wherein the payload is supported in a single gimbal and the positioning means is a stepper motor.

3. The suspension means of claim 2 wherein the means imparting the oscillatory motion to the payload is a torque motor.

4. The suspension means of claim 2 wherein the positioning means is a stepper motor in combination with a gear coupled with the flex pivot.

5. The suspension means of claim 4 wherein the means imparting the oscillatory motion to the payload is a pair of rotating unbalanced mass devices.

6. The suspension means of claim 4 wherein gimbal mounting means hold the single gimbal on a space platform.

7. A suspension means including the single gimbal suspension means of claim 4 within an outer gimbal, wherein axle means rotatably support one side of the single gimbal in the outer gimbal, and wherein a flex pivot supports the opposite side of the single gimbal in the outer gimbal in an axis perpendicular to the single gimbal axis, and wherein a second positioning means are coupled with that flex pivot.

8. The suspension means of claim 7 wherein the positioning means is a stepper motor in combination with gear means coupled with the flex pivot, and wherein gimbal mounting means hold the outer gimbal on a space platform.

9. A scanning apparatus comprising a single gimbal, a scanning device to be supported in the gimbal, a first axle means having one end attached to one side of the scanning device and its other end attached to the gimbal, a second axle means having one end attached to the gimbal, and its other end attached to the other side of the scanning device, the first axle means having one of its ends journaled to permit scanning device rotation, the second axle means being a flex pivot restricting said rotation to effect oscillation of the scanning device, the flex pivot being flexible about a torsional moment, but inflexible about bending moments, the rotation of the scanning device being limited by the torsional spring constant of the flex pivot, a pair of rotating unbalanced mass devices mounted on the scanning device to impart the oscillatory motion to the scanning device to effect a scan of a given frequency, a gear train coupled with the flex pivot to hold the flex pivot in a fixed position and a stepper motor driving the gear train to turn the flex pivot when the stepper motor is actuated.

10. The scanning apparatus of claim 9 wherein the spring constant of the flex pivot is such that the flex pivot resonance frequency matches the scan frequency.

11. The scanning apparatus of claim 9 wherein adjustable trim means are carried by the payload.

12. The scanning apparatus of claim 9 wherein damping means are mounted on the payload.

13. The apparatus of claim 9 wherein the single gimbal is mounted within an outer gimbal, with axle means rotatably supporting one side of the single gimbal in the outer gimbal, and a flex pivot supporting the opposite side of the inner gimbal in the outer gimbal in an axis perpendicular to the single gimbal axis so that the rotating unbalanced masses impart to the device a predetermined circular scan pattern.