Analysis And Design Of Networked Control Based On Hybrid System Theory

With the rapid development of computer network technology, networked control system (NCS) with the network as the transmission medium has been an important direction of control systems. NCS is a distributed system based on network. Compared with conventional point-to-point control systems, the advantages of NCS are easy information sharing, less wiring, easy system maintenance and expansion. However, new challenges are introduced by using network in analysis and design of control systems. In the field of NCS, a number of important research results have been derived until now, but there are still many problems needed to be addressed. NCS with modulation, NCS with medium access constraint and model-based NCS (MB-NCS) are studied in this dissertation, and the following results are obtained by using the theory of hybrid system, such as asynchronous dynamic system (ADS) and switched system.That the error code rate (ECR) is considered as packet loss rate is proposed for the NCS with modulation, which fills the gap of dealing with error code for modulated signal in the field of NCS. This issue is studied from two angles, binary modulation and M-ary modulation, in this dissertation. For the simple binary modulation, the NCS with constant time delay and error code is modeled as an ADS, and the stability is analyzed and the state feedback controller is designed by using Lyapunov stability theory. The ECR theory that can enable the NCS with binary modulation to be stable is obtained. For the more practical but more complex modulation, M-ary modulation, the NCS with constant time delay and error code is also modeled as an ADS, and the stability is analyzed and the state feedback controller is designed by using Lyapunov stability theory. Moreover, the ECR theory that can enable the NCS with M-ary modulation to be stable is obtained, as well as the selection theorem of M-ary modulation.The concept of coupling design of control and scheduling is first proposed for the NCS with medium access constraint. Based on communication sequence and maximum error first-try once discard (MEF-TOD), a new scheduling scheme named least-square-like scheduling (LSLS) is proposed. In the LSLS, the ideal dynamic of the system is embedded in the scheduler, and the states with large variance will gain the access to network after comparing the current states and the sates of ideal dynamic in each sample period, which effectively reduces the conservatism of analysis and design of the system. The NCS with random and short time delay and medium access constraint is modeled as a switched system based on the proposed LSLS. Then, the coupling design of LSLS and control is carried out by using switched system and Lyapunov stability theory. In addition, the proposed LSLS is improved, in which the ideal dynamics with no time delay is replaced with the one with time delay. So better performance is derived as the ideal system dynamic with time delay is capable of having a better view of the real system as a whole.The scheme that uses average dwell time (ADT) of switched system to analyze and design the MB-NCS used for saving bandwidth is proposed, in which the flexibility of analysis and design of the system is increased. Exponential stability is analyzed and state feedback controller is designed based on Lyapunov stability theory and switched system theory after modeling the MB-NCS as a switched system. Moreover, the system structure of the MB-NCS with observer in existing literatures is improved. The location of the observer before accessing the network is moved into the controller, which not only brings cost saving but also avoids losing the signal in the transmission. Finally, exponential stability is analyzed and state feedback controller and observer are designed based on Lyapunov stability theory and switched system theory after modeling the MB-NCS with observer as a switched system.The scheme using the ADT of impulsive switched control to analyze and design the MB-NCS is proposed, in which the conservatism of analysis and design of the system is reduced. By analyzing the state jumping phenomena when the network is closed, the MB-NCS can be modeled as an impulsive switched system, then exponential stability is analyzed, and state feedback controller is designed based on Lyapunov stability theory and switched system theory. In addition, exponential stability is analyzed and state feedback controller and observer are designed based on Lyapunov stability theory and switched system theory after modeling the MB-NCS with observer as an impulsive switched system based on the improved system structure of the MB-NCS with observer.Mode-dependent ADT of impulsive switched control is proposed, in which the conservatism of analysis and design of the system is further reduced. The mode-dependent ADT of impulsive switched control is dependent not only on the switching parameters of the system but also on the parameters of impulsive matrix. The sufficient conditions of exponential stability and the state feedback controller stabilizing the impulsive switched system are derived based on analysis and design of the MB-NCS under the strategy of the mode-dependent ADT of impulsive switched control. In addition, The sufficient conditions of exponential stability and the observer and the state feedback controller stabilizing the impulsive switched system are given based on analysis and design of the MB-NCS with observer under the strategy of the mode-dependent ADT of impulsive switched control.A number of illustrative instances and simulations, which are carried out in the Matlab and network environment-like TrueTime toolbox, are given to verify the effectiveness of the proposed schemes. Finally, the conclusion and future work are presented.