Robust control of uncertain aerospace and mechanical systems with unmodelled flexibilities: A singular perturbation approach

The effect of the flexibility of aerospace/mechanical elements is becoming more significant in engineering applications, e.g., light high-speed robotic manipulators and flexible space structures. In designing a controller for a flexible aerospace/mechanical system, one quite often neglects some of the dynamics of the flexible elements in order to obtain a suitable lower order model. The singular perturbation approach is one approach for developing a controller design methodology based on a lower order model for uncertain flexible aerospace/mechanical systems which guarantees robustness with respect to the uncertainties and the unmodelled dynamics. The main objectives of this thesis are: (1) To obtain several important results for singularly perturbed uncertain systems. (2) To develop a controller design methodology for uncertain flexible aerospace/mechanical systems described by singularly perturbed systems and to obtain criteria which guarantee that the desired properties of the feedback controlled systems are robust with respect to uncertainty and the unmodelled dynamics. New results in singularly perturbed systems and controller design methods are applicable not only to aerospace/mechanical systems but to all dynamical systems.