Decentralized Tracking Control For Strict-Feedback Interconnected Nonlinear Systems

With the development of society,the complexity,nonlinearity and scale of modern systems are much larger than those of the past systems,and the single system can no longer meet the actual project.Interconnected systems coupled by multiple subsystems have attracted more and more attention.However,the control system is too big and complex,the real control problems can’t be solved by one-off method,so it becomes very difficult to solve the control problems by centralized control method.Under the above difficulties,the decentralized control method was proposed.In addition,saturation nonlinearity and time delay will also increase the instability of interconnected systems.Therefore,a decentralized adaptive tracking control strategy is developed in this paper for interconnected nonlinear time delay systems.The main researches are as follows:(1)First of all,adaptive tracking control is developed for a class of interconnected nonlinear time delay systems with unknown nonlinearity and unknown time delay.The unknown nonlinearity is approximated by extreme learning machine.The Lyapunov-Krasovskii functional is introduced to deal with the unknown time delay.Finally,combined with the backstepping control technology,a decentralized tracking control strategy based on extreme learning machine is proposed.(2)Secondly,based on research point one,actuator saturation is considered in the system model.Then,for a class of interconnected nonlinear time delay systems with actuator saturation,unknown nonlinearity and unknown time delay,an auxiliary system is introduced to offset the negative effects of input saturation through the output of the auxiliary system.Extreme learning machine is used to approximate the unknown nonlinear functions.Finally,the control strategy designed in this chapter can ensure that all closed-loop signals are ultimately uniformly bounded.(3)Finally,based on research point two,the full state constraint is considered in the system model.For a class of interconnected nonlinear time delay systems with full state constraints,input saturation,unknown nonlinearity and unknown time delay,the augmented function of the auxiliary control signal is used to eliminate the influence of input saturation.Then,the nonlinear state dependent function is introduced to deal with the full state constraints.The control strategy designed in this chapter can track the reference signal effectively and ensure that the tracking error converges to a small neighborhood of the origin in a finite time.