ACTIVE SHAPE AND VIBRATION CONTROL OF FLEXIBLE SPACE STRUCTURES

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1. Since design models of flexible space structures contain significant uncertainties, the designed controller must have sufficient robustness with respect to such model uncertainties. Besides, space structures have abundant structural design freedom that enables simultaneous/integrated design of structure and controller. In this research project, a method of structure/controller design via robust pole assignment has been developed for active vibration suppression of flexible structures. The proposed method assigns the closed-loop eigenvalues at target locations and quasi-minimizes the condition number of the closed-loop modal matrix by designing structure and controller parameters. The condition number is a measure of the closed-loop system robustness that is related to the maximum deviation of the closed-loop eigenvalues subject to perturbations of the system matrix. The condition number is also a measure of the control performance, which gives the upper bound of magnitude of feedbac … More k gain matrix and transient responses. Therefore reducing the condition number improves tabiliy rebustness and control performance of the designed closed-loop system. The proposed method further reduces the resulting closed-loop condition number via structure/controller design. The target closed-loop pole locations can also be redesigned as the design parameters. A new index of condition number has been introduced as the cost function. Use of this index in place of actual condition number reduces computational effort and improves problem solvability. Feasibility of the proposed method is examined by numerical simulations.2. Fundamental studies have been done for developing methods of shape measurement, estimation and control for active shape control of flexible structures. The proposed estimation and control design methods have been applied to a tendon shape control system for a cantilevered beam. The results of numerical simulation show that the magnitude of the restoration errors largely depends on the number of available actuators and their locations. Less