OBSERVER-BASED ROBUST SLIDING MODE CONTROL FOR SPACECRAFT ATTITUDE MANEUVER SUBJECT TO REACTION WHEEL FRICTION

摘要

Reaction wheels are commonly used actuators that store and exchange angular momentum to generate the torques necessary to control and stabilize the attitude of a spacecraft. Periodic disturbances and perturbations, may lead to speed reversals (zero crossings) which cause an abrupt increase in the error of the spacecraft attitude control system. In this paper, an observer-based sliding mode controller is proposed to achieve spacecraft attitude maneuver. The influence of wheel zero-crossing on attitude control system is firstly addressed. A novel friction observer is then developed to compensate the influence of wheel zero-crossing. The convergence of the observation errors is discussed by Lyapunov method. A robust controller, based on the observer and sliding mode control approach, is therefore proposed to perform attitude maneuvers, and model uncertainties and disturbances are also addressed. Simulation results are finally provided to illustrate the performance of the proposed controller.