ACTIVE CONTROL OF ULTRALIGHT-WEIGHT AND FLEXIBLE SPACE STRUCTURES

点击翻译按钮获取中文摘要

In this research project, the use of smart structural systems has been proposed for space structures such as large flexible space antenna, where many active sensor and actuator devices are imbedded onto the structures for precision control, shape determination, and vibration suppression. The project also includes the development of software algorithms for fault detection and identification because there exists the need for developing highly reliable control systems for on-orbit application of such smart structures.(1) Studies on Controller Design for Flexible Space Structures1-1 Methods of controller design have been developed for shape and vibration control of highly flexible structures. Intensive studies have been carried out emphasizing robustness of the control system against both spillover instability and uncertain structural parameters.1-2 A method of vibration control for flexible structures with piezoelectric actuators has been developed. Sliding mode control has been applied t … More o the model of a cantilever beam with parameter errors. The designed controller shows high performance of robustness against the model errors.1-3 Simultaneous optimal design problem has been solved to find the best set of structural parameters and output controller. The proposed design method is based on Bilinear Matrix Inequality (BMI) and presents an improved branch and bound method for BMI by using graph theory. The method is useful for simple structural systems with low degrees of freedom. Further studies are needed for the simultaneous optimal design of structural/control systems in the case of more complex structures.(2) Fault Detection and Identification for Smart Structure Control SystemsModel-based FDI (Failure Detection and Isolation (FDI) systems for smart structures have been studied with careful considerations about robustness with respect to model uncertainties. A new method of robust fault detection has been proposed that is insensitive to the disturbances caused by unknown modeling errors while it is highly sensitive to the component failures. The capability of the robust detection algorithm is examined for the sensor failure of a flexible smart beam control system. The proposed method suppresses the disturbances due to model errors and remarkably markedly improves the detection performance. Less