Control And Application For A Class Of Nonlinear Systems With Input Delay

Considering the delay problem caused by the increase of signal transmaission distance,and the nonlinear problem affecting the stability of the system,this paper intends to consider a kind of nonlinear system with input delay,and carry out the control research with the prescribed performance control idea.Further more we will apply it to the cold rolling mill hydraulic automatic gauge control(HAGC)system.Firstly,we establish a nonlinear mathematical model of the HAGC system.Due to the fact that the thickness gauge usually installed in the distance to the centerline of the roll position,it inevitably produces time delay problem.Based on the practical running mechanism of HAGC system,two class of nonlinear mathematical model for control are presented by two different conditions.Secondly,based on the mathematical model of the measurable HAGC system,the input delay is considered as a constant time delay.A prescribed performance control based on neural network is proposed to obtain a superior control performance.The control effect can be changed only by adjusting the parameters of the predetermined performance function and the controller parameters.Thirdly,considering the practical HAGC system,the output feedback is more suitable for production.Therefore,considering the above-mentioned unmeasurable system with fixed input delay,and by using a radial basis network observer and asymmetric prescribed performance function,we propose an output feedback controller which is more suitable for practical application.Finally,in view of the time-varying time delay in the HAGC system,by using LMI technology and Lyapunov-Krasovskii functional,we design an output feedback controller to deal with the time-varying delay,and analyze the stability of them.Matlab simulation experiments are carried out to verify the effectiveness of the controller and observer.