Research On Robust Control Methods For Networked Control Systems With Delays

Networked Control System (NCS) is distributed control system where actuators, sensors and controllers are connected by a common communication network. Based on Internet NCS, one hand it can realize the communication during the NCS and Internet as well as during the NCSs, on the other hand it can reduce the variety of connection cables and costs and be easy to maintain. In control system, the purpose of the introduction of communication networks is to improve the control performance, but it is important to break the limit of region space and reduce the complexity of the control system to realize centralization and efficitive operations. At the same time, the insertion of the communication network in the control loop exist network delay which often result in instability and performance degradation of systems. How to effectively overcome the impact of network delay and design meeting some certain performance NCS controllers with delays are the most important problems. Consequently, the research of the NCS with delays has important theory and practical significance. This thesis gives and proves l₂-l_∞performance that ensure the peak value of control output be less than a certain value, and proposes L₁ performance criterion for the NCS with delays for the first time. The emphasis is focus on robust l₂-l_∞control and robust L₁ control for NCS with delays and robust l₂-l_∞filtering for NCS with random time delays.First of all, studying the model of NCS with delays and applying Lyapunov stability theory and linear matrix inequality (LMI) technology,we propose and prove l₂-l_∞performance criterion , design the sufficient conditions for the existence of l2-l∞robust controllerSecondly, making use of random variables of the Bernoulli distributed, the sufficient conditions for the existence of l₂-l_∞filter are proposed in terms of Lyapunov stability theory and linear matrix inequality approach, that make the filtering system to have chastically exponential stability in the mean square sense and l₂-l_∞performance.Thirdly, we discuss robust L₁ control problem of NCS with delays. We establish L₁ performance criterion which gurantees the system to be asymptotically stable and to be provided with the worst case peak-to-peak performance constraint. According to analysis of peak-to-peak performance, we design robust L₁ controller.Finally, the sufficient conditions for the existence of robust l₂-l_∞state feedback controller and robust L₁ state feedback controller contain the form of inverse constrains of LMI. The cone complementary linearization (CCL) is used to cast them into minimization problems subject to LMI constraints. Thus, by standard mathematical software, we can solve the parameters of controllers. Numerical examples are provided to illustrate the effectiveness of the proposed design method.