Variable Structure Model-Following Control of Nonlinear Systems with Application to Flexible Spacecraft

An approach devoted to the trajectory tracking of the outputs of a certain class of nonlinear systems by variable structure model-following control is studied in this paper. We show that the nonlinear system may be transformed in the output apace into an asymptotically equivalent linear system by using a suitable feedback variable structure control law. And we apply this approach in this paper to large angle rotational maneuver of a spacecraft-beam-tip body configuration. A variable structure model-following control strategy is derived to asymptotically obtain independent decouped control of attitude angles, lateral elastic deflections, slopes due to bending and angular deflection due to torsion at the tip of the beam using torque and force actuators. For the stabilization of the elastic oscillations, a linear feedback control law through the reference model, is obtained based on the linearized model of sliding motion in state space about terminal state augmented with a servocompensator.