Study On Robust Control Algorithm Of Networked Control Systems

A great deal of attention has recently been focused on a class of networked control systems (NCS) wherein the control loops are closed through communication networks. This family of systems is an integration of plants, sensors, controllers, actuators and communication networks of certain local field. It aims to ensure data transmission and coordinating manipulation among spatially distributed components. Compared with conventional point-to-point control systems, the advantages of NCS are less wiring, lower install cost as well as greater agility in diagnosis and maintenance. Because of these distinctive benefits, typical application of these systems ranges over various fields, such as automotive, mobile robotics, advanced aircraft, and so on.However, the introduction of communication networks in the control loops makes the analysis and design of NCS complex. The requirements for stable feedback control with network are not yet satisfied due to random network-induced delays, jitter, packet losses as well as limited bandwidth.In this dissertation, networked control systems in the frame of robust control theory are reasonably modeled. By introducing kinds of performance index and co-considering the robust and stability, the inner relationship between performance index and network quality is also established. With an aim to decrease the conservatism of results, new stability results and control law design methods are presented by some new techniques.Summing the distributed network-induced delays as a single delay simplifies the complex structure and design procedure of networked control systems. From the viewpoint of load-disturbance rejection, a structure with dual relay auto-tuning robust PID is proposed. On different plants, a novel digital robust PID design scheme is presented according to the structure.Time-varying delays are regarded as the sum of the mean delays and uncertain delays. Furthermore, NCS with long time delays is modeled as a discrete-time model with structural uncertainty for its time-varying network-induced delays. Based on the model, a new control law via an iterative LMI approach is presented which can stabilize the closed-loop system.Time-varying but bounded delay issue of networked control systems (NCS) within the framework of discrete-time as well as continuous-time linear state-delayed system with norm-boundeduncertainty is addressed. A delay-dependent sufficient condition for the existence of guaranteed cost controller for NCS is presented by a new Lyapunov-Krasovskii functional and descriptor systems method.Random time-delays and packet losses issues of networked control systems (NCS) within the framework of jump linear systems with mode-dependent time-delays are addressed. A new delay-dependent condition on the stochastic stability is proposed by a new stochastic Lyapunov-Krasovskii functional and slack variables method. The condition is formulated as a set of coupled linear matrix inequalities (LMIs). Then a new stable H_∞ design method is developed. Furthermore, the robust H_∞ issue of uncertain Markovian jump linear systems (MJLSs) with mode-dependent time-delays is also addressed. An H₂/H_∞ issue of networked control systems is presented without the involvement of matrix bounding technique. Therefore, the less conservative results are expected.At last, a novel testbed of Internet-based mobile robot is designed so that the remote user can control the mobile robot through Internet. The testbed also serves as a very useful tool for theoretical researchers on networked control and real-time scheduling.