Research On Two-Cylinder Synchronous Control System Based On Two-Dimensional(2D) Servo Valve

The electro-hydraulic servo system has the advantages of high power weight ratio,fast response speed and high control accuracy,which is widely used in aerospace,ship,equipment machinery and other fields.Compared with other servo valves,2D servo valve not only has high power weight ratio,small volume and simple structure,but also has strong anti pollution ability and good dynamic performance,which has been applied to a certain extent in many fields.In this paper,a two cylinder synchronous hydraulic control system is designed based on 2D servo valve.Due to the simple structure of conventional PID and the difficulty of parameter setting,it is difficult to meet the actual control requirements.In this paper,a three closed-loop algorithm based on single neuron adaptive PID control is proposed,which enables the hydraulic cylinder to reach the target position accurately,and finally realizes the synchronization of two cylinders.Through MATLAB Simulink simulation and related experiments,the double cylinder synchronous control system is studied and analyzed.The main research contents and achievements are as follows:(1)The working principle of 2D servo valve is analyzed,the transfer function of valve body is derived,and then the working principle of 2D servo valve electromechanical converter is analyzed,the mathematical model of two-phase hybrid stepping motor is derived.(2)The mathematical model of 2D valve controlled asymmetric hydraulic cylinder system is deduced,and the position closed-loop control and double cylinder synchronous control of asymmetric hydraulic cylinder are simulated respectively.The simulation shows that the double cylinder synchronous control system under single neuron adaptive PID control has good static characteristics.Finally,the speed ratio of forward and reverse motion of asymmetric hydraulic cylinder under no-load is analyzed,which provides an important reference for the experiment of dual cylinder synchronous control.(3)A dual cylinder synchronous controller is designed,which consists of two parts: hardware design and software design.The main control chip of the controller is stm32f407 produced by ST company,with the highest frequency of 168 MHz.Ads8634 with four channels is adopted,and the dual cylinder synchronous curve and control parameters are displayed in real time through LCD screen.(4)Set up experiment platform,carry out position closed-loop experiment and double cylinder synchronous experiment.In the position closed-loop experiment,the conventional PID step response experiment and the single neuron adaptive PID step response experiment are carried out first.The experiment shows that the latter has faster step response and better response characteristics.Then,the frequency response experiment is carried out,and the frequency width of the system is different under different amplitude input signals.In the double cylinder synchronous experiment,the speed of the hydraulic cylinder is reduced and the proportion coefficient of the neuron is adjusted.The experiment shows that the maximum error is 1.5% and the static error is 0.25%,which proves the validity of the three closed-loop algorithm based on single neuron adaptive PID control.