Analysis Modeling And Control Of Networked Control Systems

As the development of network technology and embedded system, together with low-cost hardware, the network based automatic control system are becoming a new application trend. Driven by the external requirement of remote control and complex control system, the analysis and synthesis of networked control system becomes one of hot research fields of control theory. The networked control of linear system, uncertain system and nonlinear system and their applications are throughly studied in this thesis by applying the robust control theory, stochastic control theory, switched control theory, time-delay system theory, and the method of linear matrix inequality. The main contents are as follows:The development and current evolvement of networked control system are summarized, and the research methods of NCS are synthetically analyzed and summarized. In order to make the modeling and design of NCS more reasonable, the transmission characteristic and delays of a few networks are analyzed and summarized in this thesis. In addition, the transmission delays of the internet are tested, and the prediction method for transmission delays by Support Vector Machine is put forward, which is important guidance for development of internet-based control system.Aiming at a class of NCS with access delay because of competition of node, the NCS is modeled as time-delay system through equivalent transformation. By applying the newest research method of time-delay, i.e. singular system method, the delay-dependent stability results which are sufficient are derived. The theorem is less conservative, and can be applied to design NCS.A class of NCS with long and stochastic delays is studied. A multi-step prediction of based on plant model is put forward to implement the compensation control for the delays respectively for the cases of state and output feedback control. In addition, the stability of NCS with compensation is analyzed, and a sufficient condition is derived. Furthermore, the compensation method is extended to the networked control of uncertain system and the sufficient condition is derived by robust control theory and LMI.The modeling and stability of NCS with multiple-packet transmission are investigated. A suitable modeling and design method is brought forward according to the transmission characteristic of fieldbus, that is the controller and the actuator are time-driven. Therefore, the NCS are modeled as switched control system, and so a sufficient stability condition is obtained.A class of affine nonlinear system of single input-single output is investigated. Firstly, the nonlinear system is transformed into an equivalent linear system through a diffeomorphism transformation. The networked control problems for the delays are constant, stochastic and shorter than a sampling period, and long and stochastic are investigated respectively. Last, the material design method and approach are presented through an example.The implementation and control of internet-based control system are considered. The internet-based level process control system is developed by applying LabWindows software and socket communication technology. The realtime control of campus network based level system is realized on the developed NCS platform. In addition, a wide area internet-based level system is also realized by using the prediction compensation method.Last, the summary of the thesis, the future work to be investigated, and the prospect of NCS are presented.