Apparatus for precision slewing of flatform-mounted devices
First Claim
1. Apparatus for oscillating a device fixed to a two degree of freedom gyroscope having a spinning rotor, said device being associated with a two-axis system said apparatus comprising, in combination:
- a) said gyroscope including a first forcer for applying a first torque with respect to a first rotor axis in response to a first alternating signal and a second forcer for applying a second torque to said rotor with respect to a second, orthogonal rotor axis in response to a second signal;
b) a first pickoff for detecting deflection of said rotor about said first rotor axis and generating a first pickoff signal in response and a second pickoff for detecting deflection of said rotor about said second rotor axis and generating a second pickoff signal in response;
c) a first motor for driving said device about a first device axis in response to said first pickoff signal and a second motor for driving said device about a second device axis in response to said second pickoff signal; and
d) a cross-axis circuit for receiving said first signal and deriving the second signal as the derivative thereof.
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Accused Products
Abstract
An apparatus and a method for controlling the path of oscillatory travel of a device within a two-axis system. A device, such as a camera, is held in a two axis gimbal system having motors for driving the azimuth and pitch axes. A two degree-of-freedom gyroscope is fixed to the case of the device. A first derivative circuit is interposed between a first input port for a loop for controlling device movement with respect to a first axis and a second input port for a loop for controlling device movement with respect to a second axis. Likewise, a second derivative circuit is interposed between the two input ports so that a periodic signal driving with respect to one axis generates a derivative function for driving with respect to the cross-axis. The cross axis signal is scaled to counteract the direct torquing of the gyro rotor that otherwise prevents smooth oscillatory slewing or scanning by the device.
25 Citations
12 Claims
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1. Apparatus for oscillating a device fixed to a two degree of freedom gyroscope having a spinning rotor, said device being associated with a two-axis system said apparatus comprising, in combination:
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a) said gyroscope including a first forcer for applying a first torque with respect to a first rotor axis in response to a first alternating signal and a second forcer for applying a second torque to said rotor with respect to a second, orthogonal rotor axis in response to a second signal;
b) a first pickoff for detecting deflection of said rotor about said first rotor axis and generating a first pickoff signal in response and a second pickoff for detecting deflection of said rotor about said second rotor axis and generating a second pickoff signal in response;
c) a first motor for driving said device about a first device axis in response to said first pickoff signal and a second motor for driving said device about a second device axis in response to said second pickoff signal; and
d) a cross-axis circuit for receiving said first signal and deriving the second signal as the derivative thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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5. Apparatus as defined in claim 1 wherein said at least one cross-axis circuit comprises an operational amplifier.
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6. Apparatus as defined in claim 5 wherein said at least one cross-axis circuit comprises said operational amplifier including a feedback resistor in parallel with a feedback capacitor.
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7. Apparatus as defined in claim 1 further comprising a second cross-axis circuit arranged to receive said second signal and to generate said first signal in response thereto.
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8. Apparatus as defined in claim 7 wherein each cross-axis circuit generates an output signal comprising a derivative of an input signal.
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9. Apparatus as defined in claim 8 wherein a gain of each cross-axis circuit is inversely proportional to a nutation frequency of said rotor.
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10. Apparatus as defined in claim 7 wherein a transfer function T(s) of each of said cross-axis circuits is
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11. Apparatus as defined in claim 7 wherein each of said cross-axis circuits comprises an operational amplifier.
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12. Apparatus as defined in claim 11 wherein each of said cross-axis circuits comprises said operational amplifier including a feedback resistor in parallel with a feedback capacitor.
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Specification