Research On Cylinder Position Servo Control Based On Bridge Energy-saving Pneumatic System

The bridge energy-saving circuit controls the intake and exhaust of the two chambers of the cylinder independently through four on-off valves.On the basis of realizing the purpose of energy-saving,the circuit can also realize a variety of functions.The purpose of this paper is to replace the proportional valve to realize the cylinder position servo control based on the bridge circuit which is controlled by digital signal,so as to reduce the cost and enhance the anti-interference ability of the control system.The main contents of this paper are as follows.(1)The servo system is designed based on the bridge circuit,PWM pulse width modulation is used to control high-speed on-off valves,and the functional principle and characteristics of valves are analyzed.The nonlinear mathematical model of the valve-controlled cylinder system is established arid the system transfer function is derived through linearization.The simulation model of the system is established based on Matlab/Simulink.(2)Research on position servo control bases on PID algorithm.Through the transfer function,the system characteristics are analyzed,and PID control parameters are designed and calculated.For the nonlinear part of the system,the flow compensation and friction compensation are designed,and the integral part is modified.It is verified by experiment that the position servo control of the system is initially realized by PID with compensation link,but the trajectory tracking performance of the system is poor,and the load change has a great influence on the control performance.(3)In order to improve the limitation of PID whose parameters are fixed,the fuzzy PID algorithm is designed,and the PID control parameters are adjusted online by fuzzy controller.The parameters of the fuzzy PID controller are designed based on the experience.On this basis,in order to further improve the control performance,the parameters of fuzzy PID controller are optimized based on genetic algorithm.Experiments show that fuzzy PID improves the control performance of the system and reduces the influence of load change.Under the set working condition,the step response of the system has no overshoot,the transition time is 0.6 seconds,and the relative average error of the system sinusoidal trajectory tracking is 2.5%.Based on the bridge energy-saving circuit,the position servo control is realized.