Dynamic bias for orbital yaw steering
First Claim
1. Satellite attitude control apparatus for use in a dynamically controlled yaw rotating spacecraft having axes for locating it in physical space and a vector defined in relation to said axes, said apparatus comprising:
- means for decoupling moments acting on the spacecraft relative to said vector defined in relation to said axes locating the spacecraft in physical space; and
sensor means, on said spacecraft, for sensing the motion of the spacecraft in two dimensions relative to said vector and producing two-dimensional sensor data indicative thereof;
means for correcting said decoupled moments in accordance with a control law referenced to said two-dimensional sensor data and producing control signals indicative thereof; and
means, responsive to said control signals, for providing three-dimensional yaw-steering attitude control relative to said two-dimensional sensor data.
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Accused Products
Abstract
A method and apparatus for steering a low-earth-orbit communication satellite requiring sun-orientation for solar-power accumulation is disclosed. Momentum-bias both maintains nadir pointing and adds yaw-steering moments for sun-trackig attitude control, simultaneously. The method has two principal steps: 1) open-loop momentum decoupling, for correcting the calculated steering torque, and closed-loop attitude compensation, to correct for perturbations about the calculated attitude in accordance with one of two control law definitions. This combines the advantage of stable gyroscopic attitude control with those of open-loop yaw steering.
34 Citations
20 Claims
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1. Satellite attitude control apparatus for use in a dynamically controlled yaw rotating spacecraft having axes for locating it in physical space and a vector defined in relation to said axes, said apparatus comprising:
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means for decoupling moments acting on the spacecraft relative to said vector defined in relation to said axes locating the spacecraft in physical space; and sensor means, on said spacecraft, for sensing the motion of the spacecraft in two dimensions relative to said vector and producing two-dimensional sensor data indicative thereof; means for correcting said decoupled moments in accordance with a control law referenced to said two-dimensional sensor data and producing control signals indicative thereof; and means, responsive to said control signals, for providing three-dimensional yaw-steering attitude control relative to said two-dimensional sensor data. - View Dependent Claims (2, 3, 4)
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5. A method for controlling spacecraft attitude in a dynamically controlled yaw rotating spacecraft having axes for locating it in physical space and a vector defined in relation to said axes, said method comprising the steps of:
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decoupling moments acting on the spacecraft relative to said vector defined in relation to said axes locating the spacecraft in physical space; sensing the motion of the spacecraft in two dimensions relative to said vector and producing two-dimensional sensor data indicative thereof; correcting said decoupled moments in accordance with a control law referenced to said two-dimensional sensor data and producing control signals indicative thereof; and in response to said control signals, providing three-dimensional yaw-steering attitude control relative to said two-dimensional sensor data. - View Dependent Claims (6, 7, 8, 9)
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10. A system for providing momentum-biased attitude control to maintain nadir-pointing and sustain yaw steering simultaneously in a dynamically controlled yaw rotating spacecraft having axes for locating it in physical space and a vector defined in relation to said axes, comprising:
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earth horizon sensing means for providing first signals indicative of pitch information and second signals indicative of roll information; momentum wheel means for providing three-axis attitude control of the spacecraft and generating third signals indicative of feedback therefrom; control law means, responsive to said first, second, and third signals, for producing control signals in accordance with a selected control law; and means, responsive to said control signals, for decoupling said momentum wheel means from moments acting on the spacecraft relative to said vector defined in relation to said axes locating the spacecraft in physical space, and generating torque command signals for modulating the rotation of said momentum wheel means to produce momentum-biased three-axis attitude control of the spacecraft. - View Dependent Claims (11, 12, 13, 14)
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15. A method for providing momentum-biased attitude control to maintain nadir-pointing and sustain yaw steering simultaneously in a dynamically controlled yaw rotating spacecraft having axes for locating it in physical space and a vector defined in relation to said axes, comprising:
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sensing the earth'"'"'s horizon and providing first signals indicative of pitch information and second signals indicative of roll information; providing three-axis attitude control of the spacecraft using momentum wheels and generating third signals indicative of feedback therefrom; in response to said first, second, and third signals, producing control signals in accordance with a selected control law; and in response to said control signals, decoupling said momentum wheels from moments acting on the spacecraft relative to said vector defined in relation to said axes locating the spacecraft in physical space, and generating torque command signals for modulating the rotation of said momentum wheels to produce momentum-biased three-axis attitude control of the spacecraft. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification