PARAMETRIC STUDY OF A LOW COST PNEUMATIC SYSTEM CONTROLLED BY ON/OFF SOLENOID VALVES

Moataz A. Youssry, Wael M. Elmayyah, Mohamed H. Mabrouk, Hussein M. Mahgoub

Abstract: Expensive proportional valves are dominantly used in pneumatic positioning systems even with low demanding accuracy positioning tasks, which deprive pneumatic systems from its economical advantages. Thereby, using low cost on/off solenoid valves instead of proportional valves has been a topic of research in the last decades. In this paper, a parametric study is conducted to investigate the effect of using low-cost 3/2 internally pilot on/off solenoid valves to control a double acting cylinder and study the system nonlinear response to on/off and PWM input signal. Matlab ® Simscape library is used to model and simulate the system. The model is validated though experimental measurements of the system behavior. The model is used to study and decrease the nonlinear pressure response associated with the cylinder chambers in addition to the evaluation of the dead zone and operating range of the on/off solenoid valve when operated with PWM signal. The results show that using a meter-in flow control and having a near constant cylinder back pressure can reduce the nonlinearity. An orifice of 1e-6 m2 can reduce the pressure variation by 80% but increase the transient time. Connecting an accumulator with 1 liter volume can result in 50% reduction in rod side pressure variation. The model has been used to predict the PWM parameters as well. It has been found that the most suitable parameters for this valve are 20 Hz and duty cycle from 12 to 65%. These results encourage going further with controlling a pneumatic position system using low-cost control valves and a simple controller.

Keywords: Pneumatic Control, PWM, On/Off Valves, Simscape, Matlab

DOI: https://doi.org/10.15623/ijret.2016.0503038