ON THE DEVELOPMENT OF A PWM CONTROL-BASED PNEUMATIC SERVOMECHANISM.

In this paper a low cost, simple, pneumatic servo system is developed to achieve accurate tracking as well as positioning control without the use of conventional servovalves. This control system is essentially an on-off servo system, which utilizes a PWM controller incorporating with the PI action. Since this control system includes critical system parameters such as the pulse frequency, pulse width of the controller, and the feedback gain parameter, a series of experiments was performed to investigate the effects of these parameters on the steady state and trasient response characteristics: As an input signal for the positioning control a step input was used, while for the tracking control a ramp signal was used. The experimental results show that high positioning and tracking accuracy as well as fast response can achieved by this simple control configuration.