Adaptive spacecraft attitude control with reaction wheel actuation

We apply retrospective cost adaptive control (RCAC) to spacecraft attitude control using reaction-wheel actuators. The controller is applied to the motion-to-rest (M2R) maneuver, where the spacecraft has an arbitrary initial attitude and angular-velocity and the objective is to bring the body to rest at a specified inertial attitude. First, we show that RCAC can complete the M2R maneuver using full information of the mass properties of the spacecraft. Then, we remove the spacecraft and reaction-wheel inertia information from the controller and examine the closed-loop settling time for off-nominal spacecraft inertias. Thus, the controller uses limited knowledge of the system. Finally, the algorithm is tested in the presence of disturbances, unknown actuator misalignment, and noise and bias in the angular-velocity measurement.