http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Maneuver and vibration control of flexible space structures by Lyapunov stability theory
This research is primarily aimed at developing control laws for maneuvers and vibration suppression of flexible space structures by using Lyapunov stability theory. The key point of the Lyapunov approach for flexible structure is to design stabilizing control laws by Lyapunov's second method without discretizing the partial differential equations modeling the original flexible systems into finite dimensional ordinary differential equations. The main analysis is focused on single axis slew maneuvers, for which both a constant gain feedback law and a near-minimum-time tracking control law are investigated. Also, results from ground-based experiments are reported which support the practical utility of the control laws By optimization of the Lyapunov control laws, a strategy for selecting a best combination of feedback gains and shaping of the reference maneuver is suggested. The optimization is carried out with the admissible solutions constrained to satisfy the Lyapunov stability conditions. The objective is to find the stable solution which extremizes a prescribed closed loop performance optimality criterion. Optimization of the reference trajectory, in addition to feedback control gains, enables one to find an optimum reference motion which is parameterized through a shaping parameter which controls the sharpness of the switching in a near-bang-bang maneuver. As a performance objective for optimization, an index which measures the trade-off between residual energy and maneuver time is used. A generalization of the Lyapunov approach is introduced, which applies to hybrid coordinate discrete/distributed parameter systems. This generalization makes use of a novel hybrid version of Hamilton's canonical equations of the systems, which is an extension of the corresponding classical results for discrete coordinate systems. The rather general form of the resulting stable family of control laws is developed in terms of the Hamiltonian of a general class of nonlinear hybrid coordinate dynamical systems. As a further extension, nonlinear hybrid coordinate systems described by discrete quasi-coordinate systems such as three axis large angle maneuvers are included in designing stabilizing control laws...