Electro-Hydraulic Speed Servo System Of Valve-Controlled Cylinder Research On Control Precision Compensation

Electro-hydraulic servo system is an important branch of hydraulic technology.In recent years,the research of electro-hydraulic servo system is generally about position control and force control,which makes these two aspects get better development.In the electro-hydraulic servo system of valve-controlled hydraulic cylinder,the speed signal is often used to control the load.Because the hydraulic cylinder completes a linear motion,the control speed can be obtained by the differential of the position signal measured by the displacement sensor.However,in practice,the position signals measured by sensors often have noise interference signals.After differentiation,the noise signals will be amplified,which makes the speed control accuracy of the system inadequate.Therefore,this paper takes the speed of electro-hydraulic speed servo system as the research object to compensate the speed control accuracy of the system.The main research contents are as follows:(1)Derivation of mathematical model of electro-hydraulic speed servo system and compensation of output speed of electro-hydraulic servo system under noise interference.In this paper,the influence of noise amplification with smaller amplitude on velocity signal is studied under the condition of better position signal accuracy.First,an electro-hydraulic speed servo system with better response is obtained by establishing simulation model.The differential velocity signal is divided into two kinds of position signals output by the system,which are noise-free and noise-free respectively.After analysis and research,the speed observer with low-pass filter is used to observe the velocity of the velocity signal disturbed by noise amplification.On this basis,the PI controller is used to compensate the observed velocity,and the Luenberger speed observer is established.The two methods are studied and analyzed separately,and the validity of compensation for the accuracy of speed control of the system is verified.(2)Based on ADRC technology,an electro-hydraulic speed servo system which can eliminate noise amplification signal is established.The extended state observer model used in ADRC technology when the output signal is disturbed by noise is adopted.Thetracking differentiator in this model is used to filter the velocity signal affected by the noise amplification signal,and then an electro-hydraulic speed servo system with anti-noise and anti-disturbance ability is constructed.The speed accuracy of electro-hydraulic speed servo system is compensated and controlled well.(3)Experiments are carried out on the valve-controlled hydraulic cylinder test bench.The speed control signals of the hydraulic speed servo system are compensated by the low-pass filter speed observer and Luenberger speed observer respectively.The effectiveness of the compensation method is proved.The electro-hydraulic speed servo system controlled by ADRC technology can achieve accurate control of the servo speed.