Systematic vectored thrust calibration method for satellite momentum control
First Claim
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1. A momentum control system for a spacecraft having a propulsion system in which a disturbance is exerted on the spacecraft, said system comprising:
- a control processor for receiving an attitude signal representative of the attitude motion of said spacecraft and processing said attitude signal to generate a state variable signal representative of one or more state variables of said spacecraft;
a system identification processor which receives said state variable signal and isolates a signal which has the characteristics of said disturbance exerted on said spacecraft, said system identification processor generating a pseudo input signal for said isolated disturbance which within a multiplicative constant has substantially the same shape, when plotted as a function of time, as the actual disturbance would have if it had been measured,said system identification processor processing said pseudo input signal to generate a thruster torque signal representative of a thruster torque generated by said propulsion system;
a propulsion processor for receiving said thruster torque signal and generating a control command signal representative of a maneuver to be performed by said propulsion system, said propulsion processor comprising a thruster calibration alignment processor which calculates the mass properties of said spacecraft in response to said thruster torque signals; and
wherein said control command signal is sent to said control processor which aligns said propulsion system in response to said control command signal.
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Abstract
A method of simultaneously performing a translational maneuver of a spacecraft by a thruster and dumping momentum from the spacecraft during a time period P. The method entails aligning the thruster along a thrust vector which is fixed during the time period P, wherein the thrust vector is aligned with the center of mass of the spacecraft at a time P/2, and firing the thruster throughout the time period P.
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Citations
14 Claims
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1. A momentum control system for a spacecraft having a propulsion system in which a disturbance is exerted on the spacecraft, said system comprising:
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a control processor for receiving an attitude signal representative of the attitude motion of said spacecraft and processing said attitude signal to generate a state variable signal representative of one or more state variables of said spacecraft; a system identification processor which receives said state variable signal and isolates a signal which has the characteristics of said disturbance exerted on said spacecraft, said system identification processor generating a pseudo input signal for said isolated disturbance which within a multiplicative constant has substantially the same shape, when plotted as a function of time, as the actual disturbance would have if it had been measured, said system identification processor processing said pseudo input signal to generate a thruster torque signal representative of a thruster torque generated by said propulsion system; a propulsion processor for receiving said thruster torque signal and generating a control command signal representative of a maneuver to be performed by said propulsion system, said propulsion processor comprising a thruster calibration alignment processor which calculates the mass properties of said spacecraft in response to said thruster torque signals; and wherein said control command signal is sent to said control processor which aligns said propulsion system in response to said control command signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of dumping momentum of a spacecraft having a propulsion system in which a disturbance is exerted on the spacecraft, said method comprising the steps of:
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receiving an attitude signal representative of the attitude motion of said spacecraft; generating from said attitude signal a state variable signal representative of several state variables of said spacecraft; isolating from said state variable signal a disturbance signal which has the characteristics of said disturbance exerted on said spacecraft; generating a pseudo input signal from said isolated disturbance signal which within a multiplicative constant has substantially the same shape, when plotted as a function of time, as the actual disturbance; and aligning said propulsion system along a thrust vector which is fixed with respect to said spacecraft in response to said pseudo input signal to thereby dump momentum from said spacecraft, such that said thrust vector is momentarily aligned with the center of mass of said spacecraft. - View Dependent Claims (8, 9, 10)
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11. A method of simultaneously performing a translational maneuver of a spacecraft by a thruster and dumping momentum from said spacecraft during a time period P, said method comprising the steps of:
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aligning said thruster along a thrust vector which is fixed with respect to said spacecraft during said time period P, wherein the thrust vector is momentarily aligned with the center of mass of said spacecraft during said time period P; and firing said thruster throughout said time period P. - View Dependent Claims (12, 13, 14)
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Specification