Variable structure control with time-varying sliding mode and vibration control for flexible satellite

A hybrid control scheme is proposed which combines the variable structure control and the intelligent vibration control. Based on the variable structure control theory, a discontinuous control law is developed with a new type of sliding surface. The variable structure control law based on a time-varying sliding surface is applied in the exterior of a small sliding region, while the conventional variable structure control law with a linear sliding surface is activated in the interior of the region. For actively damping the excited elastic vibrations, the strain-rate feedback control is also employed by using piezoelectric materials as additional sensors and actuators. Finally, simulation results show that the rotational maneuver and the vibration suppression are realized in spite of the presence of disturbance torque and control input constraint.