Research On Control System Of Low Pressure Oxygen-enriched Chamber

The average altitude of the Qinghai-Tibet Plateau is more than 4,500 meters.The atmospheric pressure decreases with the increase of altitude.The thinner the air,the lower the partial pressure of oxygen in the air.The environment of hypoxia in the plateau has different degrees of influence on the organs and systems,such as nerves,respiration,and circulation of the human body.Hyperbaric oxygen therapy has a satisfactory effect on high altitude sickness caused by hypoxia.However,hyperbaric oxygen chamber needs special venues for medical equipment,and medical staff cannot promote it to daily use.In this context,the subject proposes a micro-pressure oxygen-enriched chamber.As the first civil pressurized oxygen chamber equipment in China,Tibetan tourists and the masses can use it in daily life.On the basis of the high-pressure oxygen chamber,the micro-pressure oxygen-enriched chamber increases the diffusion oxygen supply in the chamber to create an oxygen-enriched environment.At present,the domestic hyperbaric oxygen chamber equipment mainly controls the pressure in the cabin,lacks monitoring of the oxygen concentration in the cabin,and lacks theoretical research on the pressure and oxygen concentration control algorithm,which leads to poor control effect and low automation.In view of the existing shortcomings of hyperbaric oxygen chamber equipment,this paper designs a control system for the functional requirements of the micro-pressure oxygen-enriched chamber.The specific contents are as follows:Firstly,according to the National Standard of Medical Air Compressed Oxygen Chamber(GB/T12130-2005),the design of each part of the micro-pressure oxygen-enriched chamber is carried out,such as chamber system,pressure system,oxygen supply system,etc.According to the requirement of micro-pressure oxygen-enriched environment in the cabin,the pipeline design of the system is carried out.With Siemens 1215 PLC as the main control system,the control system design of the micro-pressure oxygen-enriched cabin is established by PLC.Secondly,according to the change of pressure,velocity and oxygen supply requirement of micro-pressure oxygen-enriched chamber,the theoretical value of pipe diameter of each part is calculated on the basis of one-dimensional isentropic flow theory of compressible fluid.According to the theoretical pipe diameter value,the preliminary selection of the electric control valve is carried out,and then the rationality of the selection is checked according to the flow formula of the electric control valve.At the same time,the mathematical models of pressure and oxygen concentration in the cabin are established,and the coupling characteristics between pressure and oxygen concentration are found by analyzing the characteristics of the system.In the control method,two groups of PI controllers are used to control the pressure and oxygen concentration respectively.Simulink simulation results show that the pressure change has great influence on the oxygen concentration.Based on PI control,the control algorithm is improved.The pressure is controlled by PI,and the oxygen concentration is controlled by BP neural network.The simulation and experiment results show that the PID can accurately control the pressure rising and falling speed,and the BP neural network PID can control the oxygen concentration.Good control system can reduce the influence of pressure change on oxygen concentration.In addition,in order to realize that the television in the cabin can display the data of the system,it is combined by the PLC free port communication and the On-screen Display.Finally,on the basis of the system control requirements,the design control system flow and the upper computer WINCC man-machine configuration interface and touch screen man-machine interface,which increases the degree of automation.