Adaptive output feedback control of spacecraft with flexible appendages

An adaptive control system for the rotational maneuver and vibration suppression of an orbiting spacecraft with flexible appendages is designed. The model of the spacecraft includes unstructured modelling uncertainties. For the purpose of control, a moment generating device is located on the rigid hub. For the synthesis of the control law, only the output variable (pitch angle) is used for feedback. An adaptive feedback linearizing control law is derived for the trajectory control of the pitch angle. The structure of the controller is independent of the dimension of the state space of the spacecraft model, since unmodeled functions appearing in the inverse (feedback linearizing) control law are estimated using a high-gain observer for feedback. Simulation results for the spacecraft model of different dimensions show precise trajectory control and vibration suppression.