Command Filtered-based Finite-time Control Of Prescribed Performance For Nonlinear Systems

In recent years,with the continuous improvement of the control requirements for nonlinear systems,various advanced control methods have emerged,such as finite time control and prescribed performance control.It is worth mentioning that the problem of tracking control for nonlinear systems has been paid much attention.Among them,the tracking error is an important index to judge the tracking performance.Therefore,it is important to ensure that the tracking error converges to the minimum region of the attachment of the equilibrium point in a very short time,and to take into account the performance indicators of its dynamic and steady-state processes.Based on the backstepping method,this thesis discusses the tracking control problem of a class of nonlinear systems with strict feedback,using finite-time control,preset performance control,command filtering and adaptive control,etc.The specific research content is as follows:Firstly,based on the backstepping method,a finite-time fuzzy funnel tracking control method is proposed by using finite-time control and adaptive control.In this design,by introducing a funnel constraint function,the tracking error of the system is limited in the range of the preset funnel boundary constraint function.The preset performance control is used to ensure that the convergence speed and overshoot meet the set requirements,so that the system is semi-global real finite time stable.In order to further improve the speed of the system,a fast finite-time fuzzy funnel controller is designed on the basis of the above design and the fast finite-time control,so that the system is semi-global fast finite-time stable.Secondly,on the basis of the above design,a finite time command filter is introduced,and combined with fixed time control,preset performance control and adaptive control,a preset performance real fixed time tracking controller based on command filtering is proposed.Firstly,the equivalent error model is established by using nonlinear mapping technique and appropriate error transformation.Then the controller is designed based on backstepping method,fixed time control and adaptive control.The main innovation of this design is that its tracking error can converge to the range of the state constraint function in a fixed time,and its convergence time is independent of the initial state of the system.At the same time,the introduced instruction filter can effectively solve the problem of repeated derivation of the virtual control law in the backstepping method,and avoid the differential explosion caused by a large number of calculations.Finally,the effectiveness of the control method is further verified by simulation analysis.