Hybrid stabilizer with optimized resonant and control loop frequencies

• US 9,300,872 B2
• Filed: 01/20/2014
• Issued: 03/29/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Tolo, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Tolo, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: McClatchie, Iain Richard Tyrone
• Primary Examiner(s): Velez, Roberto
• Assistant Examiner(s): COLEMAN, STEPHEN P
• Application Number:
  US14/159,360
• Publication Number:
  US 20150264262A1
• Time in Patent Office: 799 Days
• Field of Search: 348/373
• US Class Current: 1/1
• CPC Class Codes: B60R 11/04 Mounting of cameras operative during drive; Arrangement of controls thereof relative to the vehicle
• CPC Class Codes: G02B 27/644 compensating for large deviations, e.g. maintaining a fixed line of sight while a vehicle on which the system is mounted changes course
• CPC Class Codes: H04N 23/68 for stable pick-up of the scene, e.g. compensating for camera body vibrations

Abstract

A hybrid stabilizer isolates a payload from vibrations across six degrees of freedom using an underdamped passive stabilizer in series with an active stabilizer that is mounted to the foundation, thereby improving isolation. In a first aspect, the passive stabilizer is one or more underdamped springs that reduce high frequency vibrations and in some embodiments the passive stabilizer is tuned to a resonant frequency at most half the control loop frequency of the active stabilizer. The active stabilizer is a six-axis motion platform that reduces or eliminates low frequency vibrations, particularly around the resonant frequency of the passive stabilizer. In a second aspect, the hybrid stabilizer isolates one or more cameras and is mounted to a vehicle, reducing motion blur and improving camera tracking, thereby enhancing the quality of images captured by the cameras.

Claims

1. A method comprising:

passively isolating a payload from an intermediate frame, wherein the passively isolated payload has a selected resonant frequency;

actively isolating the intermediate frame from a foundation;

controlling the actively isolating via a control system with a control loop frequency, wherein the selected resonant frequency is selected to be less than half the control loop frequency;

wherein the controlling comprises measuring characteristics of one or more of the payload, the intermediate frame, and the foundation; and

wherein the characteristics comprise one or more of linear acceleration, angular rotation rate, magnetic flux direction, air pressure, temperature, and GPS location and GPS carrier phase of one or more GPS antennae.

2. The method of claim 1, wherein the payload comprises a camera.

3. The method of claim 1, wherein the passively isolating is performed by one or more underdamped springs.

4. The method of claim 1, wherein the payload comprises a camera enabled to capture images and the characteristics of the camera further comprise motion vectors extracted from images captured by the camera.

5. The method of claim 1, wherein the controlling further comprises feed-forward and feed-back control.

6. The method of claim 1, wherein the measuring is performed by an IMU.

7. The method of claim 1, wherein the measuring is performed by a GPS unit and one or more GPS antennae.

8. The method of claim 1, wherein the controlling further comprises adjusting the actively isolating based at least in part upon the measuring.

9. The method of claim 8, wherein the actively isolating is performed by a Stewart platform comprising multiple actuators and the adjusting comprises adjusting the position of at least one of the multiple actuators.

10. The method of claim 1, wherein the foundation comprises a vehicle.

11. The method of claim 10, wherein the vehicle is one or more of:

an aircraft, an airplane, a lighter-than-air craft, a space-craft, a helicopter, a satellite, a car, a truck, a land-based vehicle, a ship, a boat, a barge, a canoe, a submersible, and a submarine.

12. The method of claim 10, wherein the vehicle is manned or unmanned.

13. The method of claim 1, wherein the actively isolating is performed by a six-axis motion platform.

14. The method of claim 13, wherein the six-axis motion platform comprises multiple actuators.

15. The method of claim 14, wherein the multiple actuators comprise six actuators.

16. The method of claim 14, wherein the adjusting comprises adjusting the position of at least one of the multiple actuators of the six-axis motion platform.

17. The method of claim 14, wherein the multiple actuators comprise at least one linear actuator.

18. The method of claim 17, wherein the at least one linear actuator is a lead-screw-type actuator.