Research On Hydraulic System Controller Based On Electro-Hydraulic Servo Valve

Hydraulic system controller regulates the spool position and the flow rate at the valve port of the proportional valve which has dead zone caused non-linear properties.PID algorithm are widely used in electro-hydraulic servo control systems with properties of simple structure,good robustness,parameters tuning hardly especially in time-varying and nonlinear servo system with multiple variables.A method for online tuning of PID parameters based on the improved PSO algorithm was studied in this thesis to solve the problems including PID parameters tuning,weak convergence of particle swarm algorithms with tendency to fall into local optimal solutions.A digital filtering algorithm was designed to optimize the immunity of the controller.A feedback compensation strategy was investigated to reduce the impact of dead zones.The feasibility of the above methods was verified by building a mathematical model of the electrohydraulic servo system and simulations based on MATLAB/SIMLINK.According to the above theories and practical needs,the controller based on SMT32 was designed with the hardware circuit of power conversion,U/I conversion,constant current source,signal acquisition,serial communication,storage,etc.and the software program of transplanting u C/OS-II,A/D conversion and filtering algorithm,data waveform fitting,control algorithm,communication,etc.Moreover,the host computer software was developed based on QT platform with the functions of data exchanging and parameter setting through the serial port,waveform fitting and display,FFT/IFFT analysis,etc.The system test platform was set up and its results show that the system has good stability,fast response and high accuracy,and meets the design requirements.