Position-based gyroless control of spacecraft attitude
AssigneeThe Boeing Company
InventorsDan Y. Liu, Richard Y. Chiang
Life of this patent
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Abstract
A system and a method for commanding a spacecraft to perform a three-axis maneuver purely based on “position” (i.e., attitude) measurements. Using an “inertial gimbal concept”, a set of formulae are derived that can map a set of “inertial” motion to the spacecraft body frame based on position information so that the spacecraft can perform/follow according to the desired inertial position maneuvers commands. Also, the system and method disclosed herein employ an intrusion steering law to protect the spacecraft from acquisition failure when a long sensor intrusion occurs.
Claims18
A system for a spacecraft having a plurality of star trackers, the system comprising a control processor configured to:
- move the star trackers to create a three-dimensional spiral acquisition pattern;
- use attitude measurements from the acquisition pattern to generate spacecraft position estimates;
- generate attitude commands;
- and
- use a position-only control on the position estimates and the attitude commands to generate actuator torque commands.
A system for a spacecraft having a plurality of star trackers, the system comprising an attitude control processor configured to:
- use attitude measurements from the star trackers to provide an attitude reference estimate for the spacecraft;
- use the attitude reference estimate to generate spacecraft position estimates;
- generate attitude commands;
- use a position-only control on the position estimates and the attitude commands to generate actuator torque commands;
- and
- continuously update the attitude reference estimate with the attitude measurements unless a sensor intrusion occurs.
A system for a spacecraft having a plurality of star trackers, the system comprising an attitude control processor configured to:
- use attitude measurements from the star trackers to provide an attitude reference estimate for the spacecraft;
- use the attitude reference estimate to generate spacecraft position estimates;
- generate attitude commands;
- and
- use a position-only control including a two-state H-infinity control on the position estimates and the attitude commands to generate actuator for torque commands.
A method in a spacecraft, the method comprising:
- generating an attitude reference estimate from star tracker attitude measurements;
- generating spacecraft position estimates from the attitude reference;
- generating attitude commands;
- and
- using the position estimates and the attitude commands to cause actuators of the spacecraft to bring the spacecraft to a commanded attitude without utilizing gyro information;
- wherein a 1-2-3 Euler sequence of rotation is used to command spacecraft attitude relative to a local inertial reference frame, and Euler angles are represented by elevation, azimuth, and rotation of boresight.
A method in a spacecraft, the method comprising:
- generating an attitude reference estimate from star tracker attitude measurements;
- generating spacecraft position estimates from the attitude reference;
- generating attitude commands;
- and
- using the position estimates and the attitude commands to cause actuators of the spacecraft to bring the spacecraft to a commanded attitude without utilizing gyro information;
- wherein gyroscopes aboard the spacecraft are kept in backup mode while the actuators are being commanded.
A spacecraft comprising:
- a plurality of star trackers;
- a plurality of torque actuators;
- and
- an attitude control processor for generating an attitude reference estimate from attitude measurements from the star trackers, generating spacecraft position estimates from the attitude reference, generating attitude commands including commands for at least one of sun acquisition and safe hold, and using the position estimates and the attitude commands to cause the actuators to bring the spacecraft to a commanded attitude without utilizing gyro information.
Dependencies are inferred from the claim text.