Satellite attitude control system
AssigneeLockheed Martin Corporation
InventorsRaymond Charles D'Ambrosio, Minh Ngoc Tran
Life of this patent
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Abstract
An attitude control system uses a first order partial derivative of an error signal, representing a difference between a commanded pitch attitude and a sensed, actual pitch attitude. The first order partial derivative forms a cross product with the Earth's magnetic field to provide a X axis torque rod dipole command, which powers the torque rod in a way that causes a satellite to move toward its commanded attitude.
Claims10
An attitude control system for effecting pitch control of a satellite, comprising:
- means for determining a first order partial derivative of an error value, the error value being a difference between a commanded pitch value and an estimated actual pitch value;
- means for producing a cross product between the first order partial derivative and a magnetic field vector of the Earth, thereby providing a torque rod dipole command;
- an X axis torque rod powered according to the torque rod dipole command;
- and
- a pitch attitude sensor providing feedback to the determining means as to the estimated actual pitch value.
An attitude control system for effecting yaw and roll control of a satellite, comprising:
- means for determining a first order partial derivative of a first error value, the first error value being a difference between a commanded yaw value and an estimated actual yaw value, and corresponding to a roll moment of inertia;
- means for determining a first order partial derivative of a second error value, the second error value being a difference between a commanded roll value and an estimated actual roll value, and corresponding to a yaw moment of inertia;
- means for determining commanded roll torque and commanded yaw torque from the roll moment of inertia and the yaw moment of inertia;
- means for producing a cross product between the commanded roll torque, the commanded yaw torque, and a magnetic field vector of the Earth, thereby providing a Y torque rod dipole command;
- a Y axis torque rod powered according to the Y torque rod dipole command;
- and
- a roll axis and yaw axis sensor providing feedback to the means for producing the first order partial derivatives.
A method of directly controlling attitude of a satellite having first and second torque rods, comprising the steps of:
- determining whether a measured pitch attitude deviates from a commanded pitch attitude;
- and
- powering the first torque rod in proportion to the pitch attitude deviation, and in conjunction with Earth's magnetic field, to produce a magnetic dipole moment which tends to correct the satellite's orbit without utilizing spinning parts.
Dependencies are inferred from the claim text.