Combined Attitude and Vibration Control for Flexible Spacecraft Based on Model Predictive Control

As the performance requirements in terms of pointing and stability of space systems grow increasingly demanding, the elastic dynamics of the flexible appendages starts to be a serious concern, particularly for satellites that call for fast and precise attitude maneuvers. One possible way to address this issue is by augmenting the AOCS (Attitude Orbit Control System) with Active Vibration Control (AVC) capabilities with the use of smart sensors and actuators. In this study a combined attitude and vibration control for a flexible satellite by means of thrusters and piezoelectric devices is proposed in the framework of Model Predictive Control (MPC). Indeed, although MPC is quite promising, it is still not extensively used for AVC applications because of the increased computational burden as sampling times become smaller and the number of state variables becomes larger. To this purpose, also an explicit solution to MPC problem is presented; in this case, the input command consists of a piecewise affine function of the states and the on-line computational effort at each time step is restricted to a lookup table. Both the beneficial features and drawbacks of MPC and explicit MPC are discussed based on numerical simulations and assessed with respect to baseline controllers.