Adaptive Robust Control For Uncertain Large-scale Interconnected Time-delay Systems

With social development and the progress of science and technology, manycomplex systems exist in nature and modern society, such as engineering, living beingsand society economy. It is unavoidable to include uncertain parameters and disturbances in practicalcontrol systems due to modeling errors, measurement errors, linearity approximations,and so on. And owing to the improvement of studying methods and the increasing needfor high accuracy of analysis and design in systems, uncertainties, which are neglectedin conventional study, have to be taken into account and attract more attention. On theother hand, because of pipe transmission processes, net transmission, large-lag linksetc., a large number of industrial processes can be modeled as time-delay systems. Theexistence of delay is frequently a source of instability and deterioration of systemperformances. Therefore, it is important to study the control problem of uncertainlarge-scale time-delay systems. Based on Lyapunov stability theory, through using linear matrix inequality andmatrix analysis as the main mathematical tools, adaptive control, decentralized controland backstepping etc. as the main discussing methods, this dissertation studies therobust control problem of uncertain large-scale time-delay systems. The majorcontributions of this dissertation are as follows: In Chapter 1, the engineering background and fundamental characters oflarge-scale interconnected systems are introduced. Then, we briefly review recentdevelopments of large-scale systems and large-scale interconnected systems. Finally,the main work in this dissertation is given. In Chapter 2, the problem of robust decentralized control for a class of linearuncertain time-delay large-scale systems is investigated. The proposed state feedbackcontrollers, which makes the closed-loop system asymptotically stable. Firstly, whenthe time-delay parameter is precisely known, the controller is designed with themethod of adaptive bounding technique and linear matrix inequality, when thetime-delay parameter is not precisely known we design an adaptive law for theparameter. In Chapter 3, the problem of robust control for a class of uncertain time-delaylarge-scale linear systems with non-linearity is studied. Firstly we connect the methodof direct adaptive to unknown parameter and linear matrix inequality. We proposed acontroller make the closed-loop system asymptotically stable, that is not only suitablefor time-delay is known but also for unknown time-delay. For the unknown parameter,we discussed time invariant and time varying two aspects. In Chapter 4, using the method of Backstepping the problem of robust control anddisturbance attenuation for a class of uncertain time-delay large-scale nonlinearsystems is investigated.