Spacecraft vibration suppression during attitude maneuver using PWPF modulated input component commands

This investigation is to apply the so-called component synthesis vibration suppression (CSVS) based feedforward control and the conventional PD feedback control to the vibration control of a flexible spacecraft. The proposed control design process is two fold: design of the attitude controller followed by the design of a flexible vibration attenuator. The attitude control law design is based on the Lyapunov stability theory to achieve a stabilizing closed-loop system. The shaped command input controller based on the CSVS method is designed for the reduction of the flexible vibration by modifying the command input, which only requires information about the natural frequency and damping of the closed-loop system. To extend the CSVS method to the system with the on-off actuators, the pulse-width pulse-frequency (PWPF) modulation is introduced to control the thruster firing and integrated with the CSVS method. The proposed control strategy has been implemented on a flexible spacecraft, which is a hub with symmetric cantilever flexible beam appendage and can undergo a single axis rotation. The results have been proven the potential of this technique to control flexible spacecraft.