Robust Optimal Control of Flexible Spacecraft During Slewing Maneuvers

In this paper, slewing maneuver of a fierible spacecraft with a large angle of rotation is cons idered and, assuminq structurol frequency uncerta inties, a robust minimum-time optimal control law is developed. Considering typical bang-bang control comman ds with multiple symmetr ical switches, a parameter optimizat ion procedure is introduced to find the control forces/ torques. The constrained minimization problem is augmen ted with the robus tn ess cons traints, which in turn increases the number of switches in the bang-bang control input to match the total number of the constraint equations . The steps of the solutionalgorithm to obtain the time optimal control input are discuss ed next. The developed control law is applied to a given satellite (hiring a slewing maneuver. The simulation results show that the robust control input with ju st few switching times can significantly lessen the vibrating motion of the flexible appendage in the presence of st ructural frequency un certain ties, which reveals the merits of the developed control law.