Sampled-data Output Feedback Control For Nonlinear Interconnected Systems

With the progress of science and technology and the development of human society,the nonlinear interconnection system with larger scale and more complex structure has attracted the attention of many scholars.It is widely used in various fields of current social life and production.At the same time,the digital computer gradually plays a more important role in the control system,which also provides an opportunity for the development of sampled-data control theory.Sampled-data control,which is more economical in communication resources and easier to implement,has become a research hotspot.In recent years,the research on sampleddata control problems has achieved fruitful results,but there are still few related results for nonlinear interconnected systems.On the basis of ensuring the control performance,further reducing the consumption of communication resources is an urgent and challenging problem to be solved.In this paper,based on the existing foundation,by using Lyapunov stability theory,stochastic system theory,homogeneous system theory,decentralized control technology,etc.,the control problem for nonlinear interconnected systems with uncertainties such as stochastic disturbances and time delays is studied.Moreover,the global output feedback sampled-data control schemes are proposed for nonlinear interconnected systems with actuator and sensor failures and two-channel denial of service(Do S)attacks.The main work of this paper is summarized as follows:(1)The output feedback sampled-data decentralized control problem is studied for stochastic nonlinear interconnected systems with time-varying delays.Compared with the systems with constant delays studied in some existing literatures,this paper studies the systems with time-varying delays which are more common in practice.A linear observer-based sampled-data control scheme is proposed,which is easier to implement in practice.By constructing an appropriate Lyapunov-Krasovskii functional and using the stochastic system theory,it is proved that the proposed sampled-data control strategy can guarantee the global mean square asymptotic stability of the corresponding closed-loop system under the allowable sampling period.(2)The output feedback sampled-data decentralized control problem is discussed for nonlinear interconnected systems with high-order power.The nonlinear functions of the subsystems in the considered system have different degrees of homogeneity,which relaxes the constraints on nonlinear functions in some existing literature.In order to deal with the nonlinear terms of different homogeneity,a new coordinate transformation with multiple scaling gains is proposed.The state observer and sampled-data controller are designed by using only the information of the system outputs at sampling times.In the stability analysis,a new Lyapunov function is constructed to derive the selection range of the allowable sampling period,and it is proved that the proposed control scheme can globally asymptotically stabilize the corresponding closed-loop system.(3)The output feedback fault-tolerant control scheme based on sampled-data control is proposed for nonlinear interconnected systems with time-varying actuator and sensor faults.Since the actual system control input and real system output are not available,a reduced order observer is designed to estimate the unmeasurable states by using the information of the fault system outputs at sampling times,and a sampled-data controller with the allowable sampling period is designed.By constructing an appropriate Lyapunov function,it is proved that all states of the closed-loop system are globally uniformly ultimately bounded under the proposed sampled-data fault-tolerant control strategy.(4)The output-feedback security control scheme based on sampled-data control is proposed for nonlinear interconnected cyber-physical systems in which both measurement and control channels are attacked by Do S simultaneously.A state observer and a sampled-data controller are constructed using the attacked outputs.Then,the effective Do S attack intervals are divided.By analyzing the stability of Lyapunov functions in the intervals classified as previously mentioned respectively,the conditions that need to be satisfied among the allowable sampling period,the duration and the frequency of Do S attacks are derived,and it is proved that all the states of the corresponding closed-loop system are globally uniformly ultimately bounded under given conditions.By analyzing the Lyapunov function in the intervals classified as previously mentioned respectively.