INPUT-SHAPED CONTROL OF 3-DIMENSIONAL MANEUVERS OF FLEXIBLE SPACECRAFT

This paper deals with the control of three-dimensional rotational maneuvers of flexible spacecraft. A spacecraft model with a cylindrical hub and four symmetric appendages is considered. The appendages are long and flexible, leading to low-frequency vibration under any control action. To provide a comprehensive treatment of input-shaped controllers (time-delay filters), both open-loop and closed-loop maneuvers are considered. For the open-loop maneuver, a five-switch, near-minimum-time bang-bang controller is designed based on the rigid-body model. The design procedure accounts for the presence of the time-delay filter for determining the switch times. In addition, a combination of a Lyapunov controller with the time-delay control technique is proposed to take advantage of the simple feedback control strategy and augment it with a technique that can eliminate the vibratory motion of the flexible appendages more efficiently.