A Novel Pneumatic Circuit Design for PWM-Driven Servo-Pneumatic Systems

In this paper, a novel pneumatic circuitcomprising of one fast switching valve isproposed which decreases the costs andcomplexity of PWM-driven servo-pneumaticsystems. In previous works, pneumaticcircuits with two or four fast switching valveshave been applied and different algorithmshave been developed to share the controlsignal between the valves. Due to having only one PWM-driven valve in the proposed circuit, the problem of allocating different duty cycles to the valves, is removed. This pneumatic circuit has also a considerable effect on the input-output linearity of the whole system which is indicated by experiments. Closed-loop tests with simple P and PD controllers are executed to investigate the positioning and tracking performances of the system. Experimental results indicate high improvements, compared to the more complicated and costly circuits and controllers of previous works. Simplicity, linearity, improved control performances and lower costs may be considered as the results of the proposed circuit.

Keywords:

Servo-pneumatic , Actuator , PWM , Switching valve , Position control