Nonlinear Optimal Control of Spacecraft with anObserver State Estimation

This study is dedicated to the problem of nonlinear attitude control for a rigid spacecraft in large maneuver. A nonlinear controller and a reducer- order observer are presented. The nonlinear control method is based on composite offeedback linearization and linear optimal controller, and the observer approach is Luenberger method. According to activity of position sensors, the angular velocities can be measured (using Gyros) and angular positions are estimated. It is assumed that only three torques in three directions on the hub are used.Actuator saturation is also considered in the design of controllers.Simulation results confirm the ability of the proposed controller and observer in tracking the attitude trajectory.

Keywords:

Spacecraft attitude control , Feedback linearization , LQR , Reduced order observer , Actuator saturation