Rapid slew and settle systems for small satellites
AssigneeThe Charles Stark Draper Laboratory, Inc.
InventorsSungyung Lim, Seamus Tuohy, Daniel Dionne, Laurent Duchesne, Louis Breger
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Abstract
A new approach for rapid slew and settle of small satellites is based on four single degree-of-freedom control moment gyroscopes with variable speed flywheels (or reaction wheels) in a pyramid configuration, combined with path and endpoint constraint time-optimal control. The path and endpoint constrained time-optimal control can be augmented with momentum management without the use of additional actuators.
Claims23
A satellite attitude control system for a satellite, the satellite attitude control system comprising:
- four hybrid control moment gyroscopes arranged in a pyramid configuration, each hybrid control moment gyroscope including a control moment gyroscope actuator and a reaction wheel actuator;
- and
- a retargeting controller for retargeting the satellite from an initial state through a desired slew and settle maneuver to a desired final state using path and endpoint constrained time-optimal control, the retargeting controller configured to determine a set of gimbal angular rate vectors based on the initial state, the desired final state, and a predetermined set of path and endpoint constraints selected to avoid control moment gyroscope actuator singularities and reaction wheel actuator singularities and to ensure that the hybrid control moment gyroscopes will complete the slew maneuver in a configuration capable of performing the settle maneuver using the reaction wheel actuators and to produce retargeting commands for the hybrid control moment gyroscopes based on the set of gimbal angular rate vectors.
A retargeting controller for retargeting a satellite from an initial state through a desired slew and settle maneuver to a desired final state using path and endpoint constrained time-optimal control, the satellite having four hybrid control moment gyroscopes arranged in a pyramid configuration, each hybrid control moment gyroscope including a control moment gyroscope actuator and a reaction wheel actuator, the retargeting controller comprising:
- a PEC-TOC control problem formulator configured to formulate a control problem based on the initial state, the desired final state, and a predetermined set of path and endpoint constraints selected to avoid control moment gyroscope actuator singularities and reaction wheel actuator singularities and to ensure that the hybrid control moment gyroscopes will complete the slew maneuver in a configuration capable of performing the settle maneuver using the reaction wheel actuators;
- and
- a PEC-TOC control problem solver configured to solve the formulated control problem to determine a set of gimbal angular rate vectors for the hybrid control moment gyroscopes.
A method for retargeting a satellite from an initial state through a desired slew and settle maneuver to a desired final state using path and endpoint constrained time-optimal control, the satellite having four hybrid control moment gyroscopes arranged in a pyramid configuration, each hybrid control moment gyroscope including a control moment gyroscope actuator and a reaction wheel actuator, the method comprising:
- using at least one processor, determining a set of gimbal angular rate vectors based on the initial state, the desired final state, and a predetermined set of path and endpoint constraints selected to avoid control moment gyroscope actuator singularities and reaction wheel actuator singularities and to ensure that the hybrid control moment gyroscopes will complete the slew maneuver in a configuration capable of performing the settle maneuver using the reaction wheel actuators;
- producing retargeting commands for the hybrid control moment gyroscopes based on the set of gimbal angular rate vectors;
- and
- providing the retargeting commands to the hybrid control moment gyroscopes.
Dependencies are inferred from the claim text.