Design And Implementation Of Low Pressure Dynamic Equilibrium Control System

The low-pressure system is an important subsystem of the national key scientific research instrument development program "High-Speed Target Plasma Electromagnetic Scientific Experimental Research Device Near Space".The pressure dynamic balance controlment is the crucial point to ensure that the pressure's stability and controllability.Scientific application value.The low-pressure system achieves the dynamic balance of air pressure through the combined control of the intake air volume and the vacuum pump exhaust volume,stably maintains the air pressure environment required for the experiment,and provides a continuously adjustable air pressure state during the experiment.By virtue of the special scientific experimental goals and experimental procedures of the Experimental device,this study designed a targeted control system based on the experimental special needs.Based on the understanding and summary of the research status in the field of pressure controlment's current development,the main works are listed next:(1)First of all,the experimental procedures and devices that this article relies on are relatively complicated.After a detailed investigation of the experimental devices,by analyzing the experimental devices and experimental processes,combining the theory of vacuum technology and the theory of pneumatic transmission,the physical derivation method is used.The study analyzed the physical mechanism of the pressure change in low-pressure system,and determined the mathematical relationship of input and controlled quantity.(2)Secondly,this paper establishes the low-pressure system model by using the process control modeling method with both static and dynamic characteristics experiments.The static model represents the steady state value that the pressure finally reaches when the input amount is determined;the dynamic model is established by step response experiments data,and determined the gain coefficient and system delay and other parameters to ensure consistency between the model and the experimental device.By analyzing the pressure dynamic model,it is found that the low-pressure system has strong non-linearity and asymmetry.The main reasons are that the system's intake and extraction volume has a certain relationship with the air pressure value,and the main devices in the process of lifting and lowering are different.(3)After analyzing the dynamic characteristics of the low-pressure system,a fuzzy control algorithm with an auto-regulation mechanism was designed to control the system.Fuzzy control is widely used algorithm in non-linear systems,and it is also appropriate for the asymmetric systems in this paper.But in for the purpose of better control effects,this paper designs an auto-adjusting parameter superimposed on the control system.The auto-adjusting controller parameter can be auto-adjusted in two situations of lifting and lowering and different operating point stages.It can offset the part of non-linear and asymmetry.In order to compare the control effect of self-adjusting fuzzy controller with conventional traditional PI controllers in depth,simulation experiments were performed on the two algorithms.After simulation by MATLAB,the results shows this algorithm can faster response time,effectively reduce overshoot,make response curve more steady and applicable to the whole common pressure section.(4)Finally,this paper designs a set of low-pressure control strategies suitable for the experimental device,including control strategy design in the experimental preparation stage and the experimental stage.The lectotype of controller and other device have been constructed,the control program and the interface design have been completed.Finally,the experimental data revealed verify the accuracy of the model and the good performance of the auto-adjusting fuzzy control algorithm proposed in this paper.The experimental results reached the technical indicators and the process control function requirements of low-pressure system.Through these four aspects of work,this paper has completed the design and implementation of a control schemes for low-pressure systems.From physical mechanism research,model establishment,control algorithm design,to the final control scheme implementation,all meet the experimental standards,strong implementability,and excellent performance,stable control of the low-pressure system is realized,and a good pressure environment is build for the plasma electromagnetic experiment.