Integral variable structure/input shaping control of flexible spacecraft

A new hybrid control system for the rotational maneuver and vibration suppression of an orbiting spacecraft with flexible appendage is designed. The proposed control system includes the attitude controller designed by integral variable structure control (IVSC) concept, and flexible vibration attenuator designed by input shaping technique. The rational for this hybrid control scheme is that the integral variable structure controller can achieve good precision pointing, even in the presence of parameter variations, uncertainties, and/or disturbances, whereas the shaped input attenuator is applied to actively suppress the undesirable vibrations excited by the rapid maneuvers. An additional attractive feature of the control system is that it integrates the pulse-width pulse-frequency (PWPF) modulator with the input shaper to accomplish the vibration reductions for the flexible spacecraft. Numerical simulation results for the spacecraft model show precise attitude control and vibration suppression.