Attitude pointing error correction system and method for geosynchronous satellites
First Claim
1. A method of correcting pointing errors in a geosynchronous satellite consequent to orbit inclination, comprising the steps of:
- establishing the momentum vector along an axis other than an axis normal to the equatorial orbit plane;
coupling the momentum vector to the satellite through at least a single degree-of-freedom connection coincident with at least a selected one of the roll or yaw axes for effecting rotation of the satellite relative to the momentum vector about the selected axis, the roll axis tangential to the orbit path and the yaw axis perpendicular to the roll axis in the orbit plane; and
torquing the satellite about the selected axis in a time-varying manner in synchronism with the orbit of the satellite and as a function of an orbit inclination angle i.
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Accused Products
Abstract
A system and method for attitude control in a geosynchronous satellite to compensate for roll and yaw pointing errors consequent to orbit inclination variation from the nominal equatorial orbit plane provides for an inertially fixed momentum vector coupled to the satellite through a gimbal system providing a one and preferably two degree-of-freedom relationship with the momentum vector. In a two degree-of-freedom embodiment, the momentum vector is established by spinning the satellite about an axis or providing an independent momentum wheel with the gimbal axes provided along the roll and yaw axes. Gimbal torquers torque the satellite about the inertially fixed momentum vector in a time-varying manner to effect correction of the roll and yaw pointing errors. Roll and yaw pointing errors consequent to orbit inclination drift from the nominal equatorial orbit are corrected in a fuel-efficient manner to extend the operating life of the satellite.
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Citations
47 Claims
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1. A method of correcting pointing errors in a geosynchronous satellite consequent to orbit inclination, comprising the steps of:
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establishing the momentum vector along an axis other than an axis normal to the equatorial orbit plane; coupling the momentum vector to the satellite through at least a single degree-of-freedom connection coincident with at least a selected one of the roll or yaw axes for effecting rotation of the satellite relative to the momentum vector about the selected axis, the roll axis tangential to the orbit path and the yaw axis perpendicular to the roll axis in the orbit plane; and torquing the satellite about the selected axis in a time-varying manner in synchronism with the orbit of the satellite and as a function of an orbit inclination angle i. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of correcting pointing errors in a geosynchronous satellite consequent to orbit inclination, the satellite of the type having a spun section that establishes a momentum vector along an axis and a despun section, comprising the steps of:
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establishing a momentum vector along an axis other than an axis normal to the equatorial orbit plane; coupling the momentum vector of the spun section to the despun section through at least a single degree-of-freedom connection coincident with at least a selected one of the roll or yaw axes for effecting rotation of the despun section relative to the momentum vector about the selected axis, the roll axis tangential to the orbit path and the yaw axis perpendicular to the roll axis in the orbit plane; and torquing the despun section about the selected axis in a time-varying manner in synchronism with the orbit of the satellite and as a function of an orbit inclination angle i. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of correcting pointing errors in a geosynchronous satellite consequent to orbit inclination, comprising the steps of:
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rotating at least one mass about an axis to establish a momentum vector along the axis, the axis other than an axis normal to the equatorial orbit plane; coupling the momentum vector to the satellite through at least a single degree-of-freedom connection coincident with at least a selected one of the roll or yaw axes for effecting rotation of the satellite relative to the momentum vector about the selected axis, the roll axis tangential to the orbit path and the yaw axis perpendicular to the roll axis in the orbit plane; and torquing the satellite about the selected axis in a time-varying manner in synchronism with the orbit of the satellite and as a function of an orbit inclination angle i. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. An attitude control system for a geosynchronous satellite, comprising:
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means for establishing a momentum vector by rotation of a mass about a spin axis, the axis other than an axis normal to the equatorial orbit plane; means for coupling the momentum vector to at least a portion of the geosynchronous satellite for controlled relative rotation of the satellite about at least a selected one of the roll axis or yaw axis, the roll axis tangential to the orbit path and the yaw axis perpendicular to the roll axis in the orbit plane; and means for driving said coupling means to effect controlled rotation of said satellite about the selected axis in a time-varying manner in synchronism with the orbit of the satellite and as a function of the orbit inclination angle i. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. An attitude control system for a geosynchronous satellite of the type having a spun section that establishes a momentum vector and a despun section, comprising:
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means defining a two degree of freedom coupling between the spun and despun sections for controlled relative rotation of the spun and depsun sections of the satellite about orthogonal roll and yaw axes defined by the two degrees of freedom coupling, the roll axis tangential to the orbit path and the yaw axis perpendicular to the roll axis in the orbit plane; and means for controlling said coupling means to effect controlled relative rotation between said spun and despun sections in a time-varying manner in synchronism with the orbit of the satellite about the earth and as a function of the orbit inclination angle i. - View Dependent Claims (44, 45, 46, 47)
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Specification