Abstract A simple design methodology of robust adaptive sliding m de utput tracking controllers for a class of MIMO nonlinear mismatched perturbed systems is presented in this thesis.First,the derivatives of tracking error

Based on the Lyapunov stability theorem, two design methodologies of adaptive block backstepping controller is proposed in this thesis for a class of multi-input systems with matched and mismatched perturbations to solve regulation problems. The main difference between these two method is that perturbation estimations are only employed in each virtual control input in the second method, whereas in the first method, the perturbation estimation is only employed in the last block. According to the number of block (m) in the dynamic equations of plant to be controlled, m-1 virtual input controllers are designed from the first block to the (m-1)th block, and the proposed robust controller is designed from the last block. Adaptive mechanisms are employed in each of the virtual input controllers as well as the robust controller, so that the least upper bounds of perturbations and perturbation estimation errors are not required. Furthermore, the dynamic equations of the plant do not need to satisfy the block strict feedback form, and the resultant control system can achieve asymptotic stability or uniformly ultimately boundedness. Finally, a numerical example and a practical example are given for demonstrating the feasibility of the proposed control schemes.

Three robust tracking control design strategies are proposed in this dissertation for different classes of nonlinear MIMO dynamic systems with mismatched perturbations. The first controller design method is proposed for a class of nonlinear MIMO dynamic systems in canonical form. The second design procedure of controller is for the nonlinear MIMO dynamic systems without canonical form. A decentralized controller is presented in the last for perturbed large-scale systems with time-varying delay interconnections, where the knowledge of the exact function of time-delay is not required. These robust tracking controllers with a perturbation estimating scheme and an adaptive control mechanism embedded are designed by means of the variable structure control technique and Lyapunov stability theorem. The adaptive control mechanism is used to adapt the unknown upper-bound of perturbation estimation error, so that the knowledge of upper-bounds of perturbation as well as perturbation estimation error is not required. The chattering phenomenon is effectively alleviated, for the gain of the proposed controllers, which needs only to overcome the perturbation estimation error, is in general smaller than those of the traditional sliding mode controllers. Furthermore, the stability of the overall controlled systems is proved, and the desired tracking accuracy can be achieved by adjusting the design parameters of the proposed controller schemes. A numerical example for each controller's design is provided for demonstrating the feasibility of the proposed control schemes.

Based on the Lyapunov stability theorem, two adaptive variable structure control (AVSC) schemes with perturbation estimation are proposed in this thesis for two different classes of nonlinear systems with model uncertainties and external disturbance, so that the robust tracking problems can be solved. The class of systems firstly considered is the one which has square input matrix gain, the other is the one which has non-square input matrix and an output function. All systems considered contain perturbation in the input matrix gain. By introducing a perturbation estimation process embedded in both proposed control schemes, not only the perturbation can be estimated, but also the control energy can be reduced. In addition, the proposed control schemes also contain an adaptive mechanism in order to automatically adapt the unknown upper bound of perturbation estimation error, so that the property of uniformly ultimate boundedness for the closed-loop system is guaranteed. Finally, four numerical examples are presented to demonstrate the feasibility of the proposed control schemes.

A simple design methodology of optimal model reference adaptive control (OMRAC) scheme with perturbation estimation for solving robust tracking problems is proposed in this thesis. The plant to be controlled belongs to a class of MIMO perturbed dynamic systems with input nonlinearity and time varying delay. The proposed robust tracking controller with a perturbation estimation scheme embedded is designed by using Lyapunov stability theorem. The control scheme contains three types of controllers. The first one is a linear feedback optimal controller, which is designed under the condition that no perturbation exists. The second one is an adaptive controller, it is used for adapting the unknown upper bound of perturbation estimation error. The third one is the perturbation estimation mechanism. The property of uniformly ultimately boundness is proved under the proposed control scheme, and the effects of each design parameter on the dynamic performance is also analyzed. An example is demonstrated for showing the feasibility of the proposed control scheme.