Adaptive Event-triggered Control Of Switched Systems With Output Constraints

With the development of human society and the progress of science and technology,more requirements are put forward for the performance of the systems.Therefore,the research on the control of switched systems with unknown parameters has become particularly important.On the other hand,the contradiction between the limited communication resources and the increasingly heavy control tasks is increasingly prominent.How to make a trade-off between these two aspects is of great theoretical and practical significance,and event triggered control has attracted more and more attention because of its advantages in overcoming the above problems.At the same time,in order to achieve better control performance,sometimes the output of the systems needs to be constrained.Therefore,in this thesis,the design of adaptive event-triggered controller are studied for the uncertain nonlinear strict-feedback switching systems with single input and single output,combined with adaptive backstepping technology,fuzzy logic system and Lyapunov stability theory.First of all,this paper briefly describes the purpose and significance of the research,the overview of related concepts and research status.And the basic theory and related lemma used in this paper are explained.Secondly,an adaptive event-triggered controller based on the common Lyapunov function is designed for the uncertain nonlinear strict-feedback switching systems with single input and single output.Firstly,the fuzzy logic system is used to model the unknown smooth functions existing in the nonlinear switching systems.Then,the known information is used to approximate it.In order to achieve better control performance,a barrier Lyapunov function is introduced to constrain the output.Morover,the intermediate control functions and the parameter adaptive law are designed by backstepping.Furthermore,to save communication resources,the adaptive event-triggered controller is designed by incorporating the event triggering mechanism with relative threshold.Finally,it is verified that the designed adaptive event-triggered controller guarantees that all the signals of the closed-loop system are bounded under any switching signals and that the tracking error converges to a small neighborhood of zero by selecting appropriate parameters,and compared with the fixed threshold event-triggered,relative threshold event-triggered saves channel resources more.Thirdly,an adaptive event-triggered controller based on piecewise Lyapunov function is designed for the switched systems with strict-feedback and uncertain nonlinearities.First of all,owing to the existence of unknown smooth functions in the nonlinear switching system,a fuzzy logic system is introduced to model it.Then,with the known information in hand,this switching system can be approximated precisely.Since the system output is the only variable to be measured,the switching fuzzy state observer is delicately designed to estimate the unmeasurable states.Then,using the backstepping method and the event triggering mechanism with relative thresholds,an adaptive event-triggered tracking controller is designed successfully.Finally,the stability of the system is proved with the help of the average dwell time method.Finally,the effectiveness of our method is further verified by simulation and it turns out that the designed adaptive event-triggered controller guarantees that all signals of the closed-loop system are bounded and the tracking error and observation error converge to a small neighborhood of zero.And by comparison,it is found that the relative threshold event-triggered save more communication resources.Finally,the main contents of this thesis are summarized,and the future research is prospected.