Active Vibration Suppression of a Nonlinear Flexible Spacecraft

In this article, the issue of attitude control and active vibration suppression of a nonlinear flexible spacecraft is assessed through piezoelectric patches as actuator and sensors. Two controller loops are applied: the inner loop, to make the panel vibration damped through piezoelectric patches; and the outer loop, to perform spacecraft maneuver using the reaction wheel acting on the hub. An optimal controller is designed in the inner loop and two robust controllers are designed as the outer loop, which are used interchangeably. One is a high-ordersliding mode controller using super twisting algorithm and the other is a nonsingular terminal sliding mode controller. With respect to the non-minimum phase properties of the system, if the panel deflection is defined as the output, the output redefinition approach is introduced.The performances of the proposed controllers are compared in terms of tracking attitude trajectory, panel vibration suppression, robustness towards uncertainties, sensor noise, disturbances and nonlinearity in large maneuvers.