Based on the Lyapunov stability theorem, a methodology of designing an adaptive sliding mode control (ASMC) scheme is proposed in this thesis for a class of linear dynamic systems with matched and mismatched perturbations. Firstly, by utilizing a pseudo control input in the design of a novel sliding surface function, one can not only suppress the mismatched perturbations in the sliding mode, but also achieve the objective of output tracking. In addition, the accuracy of output tracking can be adjusted through the designed parameter embedded in this pseudo controller. Then, a sliding mode controller is derived to guarantee the existence of the sliding mode in a finite time by using adaptive mechanism, which is used to overcome the lumped perturbations so that the upper bound of perturbations is not required. Finally, two illustrative examples are given to demonstrate the validity of the results.

Based on the Lyapunov stability theorem, a methodology of designing a decentralized multi-surface adaptive sliding mode control scheme is proposed in this thesis for a class of large-scale nonlinear systems with mismatched perturbations and interconnections. By utilizing the sliding mode control technique, the designed decentralized robust controller with adaptive mechanisms embedded enable the output of each subsystem to track its own desired output signal, and stabilize the whole large-scale system as well as each subsystem at the same time. In addition, the accuracy of output tracking can be adjusted through the designed parameter embedded in the controller. The purpose of the adaptive mechanisms included in the controller is to adapt the unknown upper bounds of perturbations and interconnections. Finally, two illustrative examples are given to demonstrate the feasibility of the proposed methodology.

Based on the Lyapunov stability theorem, an adaptive sliding mode control scheme is proposed in this thesis for a class of mismatched perturbed multi-input multi-output (MIMO) dynamic systems to solve regualtion problems. The sliding surface function is firstly designed by treating some state variables as a pseudo controllers through the usage of sliding function to stabilize the rest of state variables. In this thesis the number of these pseudo controllers is less than that of the state variables to be stabilized. The second step is to design the controllers so that the trajectories of the controlled systems are able to reach sliding surface in a finite time. Some adaptive mechanisms are embedded in the sliding surface function and sliding mode controllers, so that not only the mismatched perturbations can be suppressed during the sliding mode, but also the information of upper bounds of some perturbations are not required when designing the sliding surface function and controllers. Once the controlled system enters the sliding mode, the state trajectories can achieve asymptotical stability under certain conditions. A numerical example and a practical example are given to demonstrate the feasibility of the proposed design technique.

Based on the Lyapunov stability theorem, a modified stability analysis as well as a modified observer is proposed in this thesis for a class of uncertain nonlinear systems with an existent high gain observer. By assuming that the first two state variables are indirectly measurable, reanalyzing the stability of the error dynamics is presented first. The advantage of this modified analytic method is that the upper bound of the disturbance distribution functions is not required to be known in advance, and the asymptotic stability is still guaranteed. Next, based on this existent observer, a slightly modified observer is presented for systems with disturbances whose upper bound is unknown. An adaptive mechanism is embedded in the proposed observer, so that the upper bound of perturbations is not required to be known beforehand. The resultant dynamics of estimation errors can be driven into the sliding surface in a finite time, and guarantee asymptotic stability. A numerical example and a practical example are given to demonstrate the feasibility of the proposed observer.

Synchronization of two identical chaotic systems with matched and mismatched perturbations by utilizing adaptive sliding mode control (ASMC) technique is presented in this thesis. The sliding surface function is designed based on Lyapunov stability theorem and linear matrix inequality (LMI) optimization technique. Adaptive mechanisms embedded in the proposed control scheme are used to adapt the unknown upper bounds of the perturbations. The designed tracking controller can not only suppress the mismatched perturbations when the controlled dynamics (master-slave) are in the sliding mode, but also drive the trajectories of synchronization errors into a small bounded region whose size can be adjusted through the designed parameters. The stability of overall controlled synchronization systems is guaranteed. Application of proposed chaotic synchronization technique to secure communication as well as several numerical examples are given to demonstrate the feasibility of the proposed design technique.

Based on the Lyapunov stability theorem, an adaptive sliding mode control scheme is proposed in this thesis for a class of mismatched perturbed multi-input multi-output (MIMO) dynamic systems to solve stabilization problems. In order to suppress the perturbations in the control systems, adaptive mechanisms are employed both in sliding function and control effort, so that the information of upperbound of some perturbations is not required when designing the proposed control scheme. Due to the novel design of sliding function, the state trajectories of this system can achieve asymptotical stability in the sliding mode even if mismatched perturbations exist. In addition, with an adaptive mechanism embedded in the proposed control scheme, the controller can drive the state's trajectory into the designated sliding surface in a finite time. A numerical example is demonstrated for showing the applicability of the proposed design technique.

In this dissertation, four nonlinear controllers are proposed for different class of multi-input multi-output (MIMO) systems with matched and mismatched perturbations. All the plants to be controlled contains input uncertainty. The technique of the adaptive sliding mode control (ASMC) scheme is first introduced in order to solve the regulation or tracking problems. By applying adaptive techniques to the design of a novel sliding surface as well as to the design of sliding mode controller, one can not only enable the fulfillment of reaching mode in fi- nite time, but also suppress the mismatched perturbations when system is in the sliding mode. Secondly, the design methodology of block backstepping is proposed to solve the regulation problem in chapter 5. Some adaptive mechanisms are employed in the virtual input controller, so that the mismatched perturbations can be tackled and the proposed robust controller can guarantee stability of the controlled systems. All these control schemes are designed by means of Lyapunov stability theorem. Each robust controller contains two parts. The first part is for eliminating measurable feedback signals of the plant, and the second part is an adaptive control mechanism, which is capable of adapting some unknown constants embedded in the least upper bounds of perturbations, so that the knowledge of the least upper bounds of matched and mismatched perturbations is not required and can achieve asymptotic stability. Several numerical examples and industrial applications are demonstrated for showing the feasibility of the proposed control schemes.

Based on the Lyapunov stability theorem, an adaptive variable structure observer and a controller are proposed in this thesis for a class of mismatched perturbed multi-input multi-output (MIMO) dynamic systems with unmeasurable states to solve regulation and tracking problems. In order to estimate the unmeasurable states, a design methodology of variable structure observers is presented first. Then the controller is designed so that the trajectories of the controlled systems are able to reach sliding surface in a finite time. Some adaptive mechanisms are embedded in the sliding surface function and sliding mode controllers, so that not only the mismatched perturbations are suppressed effectively during the sliding mode, but also the information of upper bounds of some perturbations are not required. When the controlled system is the sliding mode, the stability or asymptotical stability is guaranteed. A numerical example and a practical example are given to demonstrate the feasibility of the proposed design technique.

No description available.

A methodology of designing an adaptive sliding mode controller for a class of nonlinear systems with matched and mismatched perturbations is proposed in this thesis. A specific designed sliding surface function is presented first, whose coefficients are determined by using Lyapunov stability theorem and linear matrix inequality (LMI) optimization technique. Without requiring the upper bounds of matched perturbations, the controller with adaptive mechanisms embedded is also designed by using Lyapunov stability theorem. The proposed control scheme not only can drive the trajectories of the controlled systems reach sliding surface in finite time, but also is able to suppress the mismatched perturbations when the controlled systems are in the sliding mode, and achieve asymptotic stability. In addition, the proposed control scheme can be directly applied to a class of underactuated systems. A numerical example and a practical experiment are given for demonstrating the feasibility of the proposed control scheme.