Near-minimum-time control of smart structures for slew maneuver
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We present a methodology for designing globally stable tracking controllers for both laree-angle slewing and vibration suppression of flexible space structures, which makes use of both reaction wheel torquing and piezoelectric actuation. For illustration, we consider a flexible space structure configuration consisting of a reaction wheel mounted on a central hub and four cantilevered appendages to which piezoelectric actuators and sensors are attached Lyapunov stability theory is applied to a hybrid ordinary/partial differential equation model of the dynamics to establish a stable controller for simultaneous slewing and vibration suppression. Two different control laws are developed utilizing a hybrid set of sensors and actuators: piezoelectric sensors/actuators, and a reaction wheel. Analytic expressions of the performance index are derived for a constant gain control law to find the optimal gain set which guarantees excellent performance characteristics beyond the realm of global stability. The formulation is such that the reaction wheel and piezoelectric control inputs are independently stabilizing and can either be simultaneously or independently tuned over a known stable region of gain space. Simulations are presented which establish a basis for our conclusion that both controllers are very attractive for a class of practical applications.