Research On Robust Adaptive Backstepping Control For Some Classes Of Uncertain Systems

The development of nonlinear geometric methods was a remarkable achievement in the 1980s. One of the breakthroughs in nonlinear adaptive control is undoubtedly the introduction of backstepping design technique for strict-feedback systems, which provides a general recursive constructive tool to design globally stabilizing controllers and resolves several technical issues arising in early development of nonlinear control such as relative-degree constraint, growth condition. The fact that many physical systems are nonlinear and subject to all kinds o f disturbances motivates the study of robustness controller for nonlinear systems in the presence of uncertainties consisting parametric uncertainty, uncertain nonlinear functions, zero dynamics, the input unmodeled dynamics, the output unmodeled dynamics and stochastic perturbations.The aim o f t his w ork i s t o generalize c lasses o f sy stems t hat c an b e s tabilized b y adaptive backstepping techniques. The following problems are considered separately. Reduced-order design of robust adaptive backstepping controllerFor a class of systems with unmodeled dynamics, robust adaptive stabilization problem is considered. Firstly, by a series of coordinate changes, the original system is reparameterized. Then, by introducing a reduced-order observer, an error system is obtained. Based on the system, a reduced-order adaptive backstepping controller design scheme is given. It is proved that all the signals in the adaptive control system are globally uniformly bounded, and the regulation error converges to zero asymptotically. Due to the order deduction of the controller, the design scheme in this dissertation has more practical values. Robust adaptive backstepping control for nonlinear systems with different unmodeled dynamicsFor a more general class of uncertain nonlinear systems with zero dynamics, output unmodeled dynamics, uncertain nonlinear functions and parametric uncertainty, by using small-gain theorem, the backstepping design and changing supply function techniques, a modified robust adaptive controller is proposed. It is shown that all the...