Study On Pneumatic Proportional Position Control System For SDA Property Testing Equipment

Pneumatic systems have been used widely in industrial automation fields for its advantages of simple structure,cost-effective,high reliability and anti-pollution.The application of pneumatic position control system is limited in industrial fields,as the development of pneumatic positioning technology become slowly. The traditional pneumatic position control system could positioning at two adjustive positions,while its movement is controled only by the one-way restrictive valve,so the control accuracy and performance is far away from the the desired results.Pneumatic proportional pneumatic technology breaks through the traditional positioning method, which make pneumatic positioning from the field of logic control extend to the proportional&servo control field.The pneumatic proportional control system which is composed of proportional control valve,could ealily control the cylinder pressure,flow,speed and position.Because of the inherent shortcomings of the pneumatic position control system such as nonlinear of valve,compressibility of the gas and cylinder friction, it is essentially a nonlinear system,which largely increases the system difficulty to control,the performance and accuracy of conventional control system is far away from the requirements of flexible production automation equipments.If we introduce the troditional pneumatic position system to the air load simulation institutions of the SDA property testing equipment, the adjustment process of initial cavity volume is too cumbersome,and the positioning accuracy is not satisfactory.This paper introduce the pneumatic position system composed by proportional directional valves,and gain a satisfactory positioning accuracy in the experiment, make the accurate adjustment of initial cavity volume a reality.This paper based on the nonlinear characteristics of the pneumatic position system, established a mathematical model,and study on the control strategy of the system.First, this paper summarize the pneumatic proportional system features and development status,establishe the pneumatic proportional system for the air load simulation institutions,based on the experimental requirements of the SDA property testing equipment.Based on depth analysis of the control system performance and features,establish the mathematical model through some reasonable and necessary assumptions and linearization,by using the aerodynamics, thermodynamics and Newtonian mechanics.Secondly, investigate the study and application of the control strategy for pneumatic proportional position control system,based on the nonlinear characteristics of the system,design the Fuzzy-PID controller.Combine the fuzzy control and the PID control,using fuzzy reasoning algorithm,make PID controller parameters on-line self-tuning to its best,according to the input error and error variation,and finally get the satisfactory effect.In the end, design the Fuzzy-PID controller for pneumatic proportional position control system through MATLAB/Simulink,and make simulation analysis at last.The simulation results show that the Fuzzy-PID controller based on fuzzy reasoning algorithm is more effective than traditional PID on the pneumatic proportional position control system,which meet the positioning accuracy requirements of the air load simulation institutions in the SDA property testing equipment.