Research On Feedforward PID Controler Based On Intelligent Optimization Algorithm For Direct Drive Pump-controlled Electro-hydraulic Servo System

Electro-hydraulic servo drive technology have been widely used in the aviation,engineering machinery, machinery manufacturing and other fields with high precision control,fast response, output power and other advantages. The valve-controlled electro-hydraulic servo drive system which is sensitive to oil pollution, complicated and lower efficiency is widely used.In this paper, a new type of electro-hydraulic servo drive system is established by using servo motor driving the two-way quantitative pump directly, the control system parameters optimization and system dynamic response characteristics have been researched by using the modern control theory and intelligent optimization algorithm.The structure and working principle of the direct drive pump-controlled electro-hydraulic position and pressure servo system are analyzed and summarized, the system is divided into several independent modules by using the thoughts of the modularization, the nonlinearity of each module is linearly assumed, the mathematical model of the differential equations of motion of each module is established by analytic modeling method, the transfer function of position and pressure servo system is constructed. the stability of the system is analyzed by MATLAB software based on the frequency domain characteristic curve of the system, the results show that the open-loop transfer function Bode graphs of the pressure servo system and the position servo system have large phase margin and amplitude margin, and the system is closed-loop stable in a certain gain range.The theory of PID control and the problem of the parameter is hard to set are elaborated systematically, The intelligent optimization algorithm is used to optimize the PID parameters.the optimization model of the parameters of the control system based on genetic algorithm and bacterial foraging algorithm is established, the simulation results show that the intelligent optimization algorithm can quickly and accurately search the PID parameters with better system response performance within a given range.In order to weaken the system's inherent uncertain hysteresis, time-varying and nonlinear factors on the fast response of the system, the feedforward PID controller is designed based on the traditional PID control, the PID parameters and feedforward quantities are optimized off-line by the intelligent optimization algorithm, and the step response and cosine tracking characteristics of the feedforward PID control based on intelligent optimization algorithm for direct drive pump-controled electro-hydraulic position servo system are simulated, the results show that the feedforward PID control based on intelligent optimization algorithm can effectively improve the dynamic response precision of the system, and it has the advantages of high control precision, fast response speed and small steady-state error.In this paper, the system experimental platform is built based on the CQYZ-D electro-hydraulic servo console, and the software development of the direct drive pump-controlled electro-hydraulic servo control system on the Lab VIEW platform is completed.The relationship between the parameters of the controller and the performance index is established by using the radial basis proxy model. The PID parameters and the feedforward quantity are optimized by the intelligent optimization algorithm off-line, the step response and square wave response characteristics of the position and pressure servo system are compared and analyzed. The results show that the feedforward PID control based on the intelligent optimization algorithm can effectively improve the control precision of the direct drive pump electro-hydraulic servo system , it has less adjustment time and steady-state error.