Attitude tracking and vibration suppression of flexible spacecraft using implicit adaptive control law

Control degree of freedom is much fewer than the motion degree of freedom when a flexible system is commanded to track a desired trajectory. Many control strategies that succeed in the conventional rigid systems, cannot be directly applied to control of flexible systems. In this paper, a nonlinear control scheme is proposed as a solution of these problems in attitude control of a flexible spacecraft. In particular, to cope with the existing model uncertainty, an adaptive version of the control law is proposed. The model of the spacecraft considered as a rigid central body and two elastic appendages. Stability proof of the overall closed loop system is given via Lyapunov analysis. Numerical simulations show the effectiveness of the proposed controller.