Gimbal positioning with target velocity compensation

• US 9,681,065 B2
• Filed: 06/15/2010
• Issued: 06/13/2017
• Est. Priority Date: 06/15/2010
• Status: Active Grant

• Current Assignee: Teledyne FLIR LLC (Teledyne Technologies Incorporated)
• Original Assignee: FLIR Systems, Inc. (Teledyne Technologies Incorporated)
• Inventors: Evans, Stewart W., Williams, Anca G.
• Primary Examiner(s): Torrente, Richard
• Application Number:
  US12/816,308
• Publication Number:
  US 20110304736A1
• Time in Patent Office: 2,555 Days
• Field of Search: 348169, 348 36, 701 2, 318696, 356 502
• CPC Class Codes: G01C 21/18 Stabilised platforms, e.g. by gyroscope
• CPC Class Codes: H04N 5/33 Transforming infrared radiation cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20

Abstract

A gimbal system, including components and methods of use, configured to track moving targets. More specifically, the disclosed system may be configured to orient and maintain the line of sight (“los”) of the gimbal system toward a target, as the target and, in some cases, the platform supporting the gimbal system are moving. The system also may be configured to calculate an estimated target velocity based on user input, and to compute subsequent target positions from previous positions by integrating the estimated target velocity over time. A variety of filters and other mechanisms may be used to enable a user to input information regarding a target velocity into a gimbal controller.

Claims

1. An optical system for tracking a moving target, comprising:

a pointing device attachable to a flight capable support platform, wherein the support platform provides information to a controller regarding a motion of the support platform;

a sensor, supported by the pointing device and pivotably orientable with respect to the support platform about a pair of nonparallel axes by controlled driven motion of the pointing device to provide pan and tilt movement of the sensor, such that the sensor can be pointed toward the moving target;

a user input device configured to receive information regarding position and velocity of the moving target, wherein the information regarding position and velocity is not provided by the moving target;

wherein the controller is configured to;

receive the information regarding position and velocity of the moving target;

receive the information regarding the motion of the support platform;

determine a line of sight vector extending from the pointing device toward the moving target using the received information regarding the position and velocity of the moving target and the motion of the support platform; and

provide the line of sight vector to the pointing device to orient and maintain the sensor'"'"'s line of sight toward the moving target based on the line of sight vector.

2. The system of claim 1, wherein the information provided by the user input device further includes information used to determine a direction from the pointing device to the moving target, wherein the controller is configured to calculate a corresponding position of the moving target using the determined direction, and wherein an initial target velocity is determined by the controller from an initial position of the target and a subsequent position of the target provided by the user input device.

3. The system of claim 2, wherein a position of the support platform is determined by at least one of a global positioning system and an inertial navigation system, and wherein the controller is configured to calculate the position of the moving target using the position of the support platform and the determined direction from the pointing device to the moving target.

4. The system of claim 1, wherein the controller is configured to compute a vector sum of (i) a change in target velocity associated with the information provided by the user input device and (ii) a previously determined target velocity, and to cause the pointing device to maintain its line of sight toward a position moving at a velocity corresponding to the vector sum.

5. The system of claim 1, wherein the controller is configured to interpret a first type of information provided by the user input device as a change in target velocity and a second type of information provided by the user input device as a change in target position.

6. The system of claim 5, wherein the first type of information is a continuous nonzero joystick input for a time greater than a predetermined minimum time, and the second type of information is a nonzero joystick input for a time less than the predetermined minimum time.

7. The system of claim 1, wherein the information provided by the user input device is sufficient to maintain the line of sight of the pointing device toward the moving target for an initial interval of time, and wherein the controller is configured to calculate an initial velocity of the moving target using a corresponding rate of change of attitude of the pointing device.

8. A method of tracking the moving target using the optical system of claim 1, the method comprising:

acquiring the moving target in a field of the sensor;

calculating an initial velocity of the moving target based on an orientation of a line of sight of the sensor toward the moving target at two different times; and

keeping the moving target in the field of view while the target is moving by either (i) causing the field of view to track a point moving with velocity corresponding to the initial velocity of the moving target, or (ii) receiving information relating to a change in target velocity, using the information to determine the change in target velocity, and causing the field of view to track a point moving with a velocity corresponding to a vector sum of the initial velocity and the change in target velocity, wherein the information relating to the change in target velocity is not provided by the moving target.

9. The method of claim 8, wherein keeping the moving target in the field of view includes interpreting a first type of information as relating to a change in target position and interpreting a second type of information as relating to the change in target velocity, wherein the information relating to the change in target position is not provided by the moving target.

10. The method of claim 9, wherein the first type of information is a nonzero joystick input having a duration less than a predetermined minimum duration, and the second type of information is a nonzero joystick input having a duration greater than the predetermined minimum duration.

11. The method of claim 8, wherein keeping the moving target in the field of view includes compensating for a nonzero velocity of the sensor relative to the Earth.

12. An optical device for tracking a moving target, comprising:

a gimbal system attachable to a flight capable support platform, wherein the support platform provides information to a controller regarding a motion of the platform;

an imaging system, supported by the gimbal system and pivotably orientable with respect to the support platform about a pair of nonparallel axes by controlled driven motion of the gimbal system to provide pan and tilt movement of the imaging system, such that a line of sight of the imaging system can be pointed toward the moving target;

a display configured to present images of the moving target collected by the imaging system;

a user input device configured to receive information regarding successive positions of the moving target, based on images of the moving target presented on the display, wherein the information regarding the successive positions is not provided by the moving target; and

wherein the controller is configured to;

receive the information regarding the successive positions of the moving target;

receive the information regarding the motion of the support platform;

determine a line of sight vector extending from the imaging system toward the moving target using the received information regarding the successive positions of the moving target and the motion of the support platform; and

provide the line of sight vector to the gimbal system to orient and maintain the line of sight of the imaging system toward the moving target based on the line of sight vector while the target moves between two positions, thereby allowing the imaging system to track the target.

13. The device of claim 12, wherein the user input device is configured to receive information regarding a change in target velocity, and wherein the controller is configured to compute a vector sum of (i) the change in target velocity associated with the information regarding successive positions of the moving target provided by the user input device and (ii) a previously determined target velocity, and to cause the imaging system to maintain its line of sight toward a position moving at a velocity corresponding to the vector sum.

14. The device of claim 13, wherein the controller is configured to interpret a first type of information provided by the user input device as a change in target velocity and a second type of information provided by the user input device as a change in target position.

15. The device of claim 12, wherein the controller is configured to cause the imaging system to maintain its line of sight toward the moving target while the support platform moves.

16. A method of tracking the moving target using the optical device of claim 12, the method comprising:

receiving information regarding an initial position of the moving target, wherein the information regarding the initial position of the moving target is not provided by the moving target;

directing the gimbal system to point the imaging system toward the initial position of the moving target;

receiving information regarding a subsequent position of the moving target, wherein the information regarding the subsequent position of the moving target is not provided by the moving target;

directing the gimbal system to point the imaging system toward the subsequent position of the moving target;

calculating an initial target velocity using a rotation rate of a line of sight from the imaging system to the target as the line of sight rotates between the initial position of the moving target and the subsequent position of the moving target; and

directing the gimbal system to point the imaging system to follow a point moving with a velocity corresponding to the initial target velocity, thereby tracking the target while the target moves.

17. The method of claim 16, further comprising:

receiving information relating to at least one of a change in target position and a change in target velocity, wherein the information relating to at least one of the change in target position and the change in target velocity is not provided by the moving target;

calculating the change in target position and the change in target velocity corresponding to the received information relating to at least one of the change in target position and the change in target velocity;

directing the gimbal system to point the imaging system toward a position including the change in target position; and

directing the gimbal system to follow a point moving with a velocity corresponding to a vector sum of the initial target velocity and the change in target velocity.

18. The method of claim 17, wherein the calculating the change in target position and the change in target velocity includes determining which received information relates to the change in target position and which received information relates to the change in target velocity.

19. The method of claim 18, wherein the determining which received information relates to the change in target position and which received information relates to the change in target velocity includes interpreting nonzero received information having a continuous duration less than a predetermined minimum as the change in target position, and interpreting nonzero received information having a continuous duration greater than a predetermined minimum as the change in target velocity.

20. The method of claim 16, wherein the directing the gimbal system to point the imaging system toward the moving target includes compensating for known movement of the gimbal system.