COMPENSATION FOR OVERFLIGHT VELOCITY WHEN STABILIZING AN AIRBORNE CAMERA
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Abstract
A method and system for maintaining the line of sight of an airborne camera fixed on a target by compensating for overflight velocity of the aircraft. The compensation system automatically commands an angular velocity of the line of sight to maintain the camera pointing at the target being overflown. This angular velocity of the line of sight is computed based upon the aircraft overflight velocity and upon a vector from the aircraft to the target. This automatic compensation for aircraft overflight velocity causes the line of sight to remain fixed upon the target. The compensation system drives a gimbal system upon which the camera is mounted to perform this compensation automatically.
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Citations
54 Claims
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1-32. -32. (canceled)
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33. A method for controlling a line of sight of a camera to remain fixed on a target, the camera being on an aircraft whose current position is moving at a velocity relative to a current position of the target, the method comprising:
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determining a static adjustment including, calculating a first position vector between the aircraft and the target, and calculating a normalized position vector indicating the difference in scan and tilt directions between a current line of sight of the camera and a desired line of sight to the target as indicated by the calculated position vector; determining a dynamic adjustment including, calculating a first velocity vector between the aircraft and the target, calculating a normalized velocity vector indicating an angular velocity that the camera is to move in the scan and tilt directions to compensate for overflight velocity as indicated by the calculated velocity; and maintaining the line of sight of the camera based at least in part on a weighted sum of the determined static and dynamic adjustments. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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41. A method for controlling a line of sight of a camera, the method comprising:
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determining a static adjustment including, calculating a position vector between the camera and the target Δ
R as Δ
R=Rtarget−
Rcamera, wherein Rtarget represents the current position of the target and Rcamera represents the current position of the camera,calculating a position vector between the camera and the target in a camera reference frame Δ
RC by transforming the position vector Δ
R to the camera reference frame,calculating a normalized position vector Δ
{tilde over (V)}C asthe normalized position vector indicating the difference in scan and tilt directions between a current line of sight of the camera and a desired line of sight to the target as indicated by the calculated position vector. - View Dependent Claims (42, 43, 44, 45, 46)
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47. A system for controlling a line of sight of a camera comprising:
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a component that determines a dynamic adjustment at least in part by, calculating a velocity vector Δ
VE between the camera and the target in an earth reference frame as Δ
VE=VtargetE−
VcameraE, wherein VtargetE represents the current velocity of the target and VcameraE represents the current velocity of the camera,calculating a velocity vector Δ
VC between the camera and the target in a camera reference frame by transforming the velocity vector Δ
VE to the camera reference frame, andcalculating a normalized velocity vector Δ
{tilde over (V)}C asthe normalized velocity vector indicating an angular velocity that the camera is to move in the scan and tilt directions to compensate for the velocity of the camera. - View Dependent Claims (48, 49, 50, 51, 52)
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53. A method for controlling a line of sight of an airborne camera to remain fixed on a target, the camera moving at a velocity relative to the target, the method comprising:
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determining a static adjustment command indicating differences in scan and tilt directions between a current line of sight of the camera and a desired line of sight to the target; determining a dynamic adjustment command indicating an angular velocity at which the camera is to move in the scan and tilt directions to compensate for overflight velocity; combining the adjustment commands with a weighting function to determine a control command; and applying the control command to the camera.
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54. A camera sighting adjustment method for a gimbaled camera having capability for scan and tilt adjustments, comprising the steps of:
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combining a static adjustment command indicating scan and tilt direction adjustments with a dynamic adjustment command indicating an angular velocity at which the camera is to move in the scan and tilt directions to compensate for overflight velocity using a weighting function to determine a control command; and applying the control command to the camera.
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Specification