Research On Finite-time Adaptive Control Of Fuzzy System With Time Delay In Solidification Process

The solidification process system exists in many fields of industrial production,such as aerospace,food,chemical and so on.The control accuracy of a certain physical quantity,such as temperature and pressure,has a great impact on the quality of the final product.For example,if the cooling temperature is low,the solidification process will be faster,and there may be gaps,bubbles and other damages inside.Therefore,the research on its process control technology has important practical significance.The solidification process generally involves physical reactions and even chemical reactions,which have time-delay and nonlinear characteristics.The existence of time-delay will make the state change of the system and the output of the controller unsynchronized,thus reducing the system performance.For nonlinear systems,direct analysis and processing and singlepoint local linearization methods are generally used,which will make the research of the control system and the design of the controller more complex,and it will lose more dynamic characteristics of the system.On the other hand,the results obtained by the traditional controller design method are more gradual and stable,which may produce more uncertainties.In actual production,due to its production benefits and costs,it is often necessary to make the system stable in a limited time.Finally,there is usually the influence of external interference in the solidification process,so it is necessary to suppress the interference to ensure the robustness of the system.Therefore,this paper proposes a finite time adaptive control strategy based on T-S fuzzy model to solve the above problems.The specific research contents are as follows:(1)The mechanism of a concrete solidification process system is modeled,and the mathematical model of the actual industrial cooling molding control system is established.Select the appropriate working point according to the actual physical conditions,change the established nonlinear system into a local linear equation at the selected working point,and finally select the trapezoid fuzzy membership function to obtain the T-S fuzzy model of the solidification process system.(2)For the nonlinear system of solidification process with time-varying time delay,in order to solve the time delay problem,a first-order integral Lyapunov-Krasovskii function with memory term is constructed,and the idea of finite-time adaptive control is added,and the T-S Fuzzy Finite-time Adaptive Memory Controller(T-S-FFTAMC)is designed,It is proved that the designed controller can make the closed-loop system stable in finite time,and the solution of the linear matrix inequality system of the controller is obtained.Based on the common chemical process systems in industry,simulation experiments are designed to verify the effectiveness of the control methods proposed in this paper.(3)For a nonlinear solidification process system with unknown time-varying delays and simultaneous disturbances,a second-order integral Lyapunov Krasovskii function with a memory term is constructed to solve the time-delay problem.On the other hand,combining robust conditions to suppress the effects of disturbances in the system,a constrained fuzzy finite time adaptive robust control strategy is proposed,It is proved that the designed controller can make the closed-loop system globally stable in finite time,and the effectiveness of this method is further demonstrated by combining with a hardware-in-the-loop simulation platform.