Composite control of tethered flexible spacecraft

A new composite control strategy is proposed for the active vibration suppression in slewing maneuvers of tethered flexible spacecraft. This strategy consists of a compensation control system designed by using optimal control method and a main control system designed by using variable structure method. The optimal controller is used to realize active vibration suppression of the flexible structure. Taking the unilateral and saturated constraint of the tethers into account, a piecewise nonquadratic cost function is introduced to derive the optimal control law for the tether tension control. The variable structure controller is able to control the attitude of the flexible spacecraft and to suppress the vibration of the flexible structure when the compensation control system is invalid. Simulation results show that the proposed control strategy can realize the slewing maneuver of the flexible spacecraft and significantly reduce the vibration of the flexible structure during and after the maneuver operation.