Feedback Linearization Control Of Coupled-tank System Based On Fluid Leakage Compensation

The process control technology of multi-tank liquid level system is widely used in petrochemical industry,sewage treatment,beverage processing and other fields.In this paper,the double tank experiment equipment produced by Quanser Company in Canada is taken as the research object to study the method of liquid leakage detection and liquid level control in the case of liquid leakage.Firstly,a mathematical model of the two-tank system was established according to the mechanism,and an improved particle swarm optimization algorithm was proposed for the flow coefficient,in which the inertia weight changed according to the nonlinear decreasing law of the number of iterations,so as to improve the convergence speed and accuracy of the optimization.Based on the mathematical model of double tank,a liquid leakage detection method based on extended state observer was proposed.Firstly,the liquid leakage is regarded as an extended state of the system,and the expression of the extended state observer is derived.Then,the influence of the relevant parameters of the observer on the observation performance is discussed.Finally,the real-time liquid leakage detection value is applied to the PID control law as feedforward compensation to improve the control performance of the system.The experimental results show that the designed expanded state observer can detect the liquid leakage at the bottom of the water tank timely and accurately,and the closed-loop system after the liquid leakage compensation can ensure the liquid level stability when the liquid leakage occurs,the liquid level fluctuation is small,and the disturbance suppression ability is significantly improved.Secondly,in order to improve the performance of the double tank system,using the input-output feedback linearization principle,according to the mathematical model of the double tank,the derivative of its output components until the expression of the control system input variables,select the appropriate input to get a new second order linear system system.Then,the optimal control law is designed according to the linear system,and the appropriate parameters are selected by the linear quadratic regulator method.Finally,the closed-loop exponential stability of the double tank system is realized.Finally,based on PLC controller to double tank leakage detection and compensation method engineering implementation,first use Win CC to draw double tank upper computer monitoring interface;Then write analog input,analog output,PID control program in Step7 software;Finally,the C script of Win CC is used to calculate the liquid leakage.The real-time control of the water tank level system is completed,and the output curves of the system with and without liquid leakage compensation are compared.The experimental results show that the liquid leakage observer is effective,which has certain guiding significance for practical engineering application.