This thesis deals with the valve operating algorithm for improving the position control of pneumatic servo system which is composed of on-off valves. Recently by the development of a fast, accurate, and inexpensive position-controlled pneumatic actuator, pneumatic servo systems are applied to many industrial fields. In many pneumatic servo systems costly servo valves are used. It is possible to construct more economical servo system if on-off valves are substituted for servo valves. Improving control performance may allow on-off valves are used in place of servo valves.
Proposed valve operating algorithm which is based in all valve-operating cases of moving cylinder piston is proposed. It develops from pulse width modulation (PWM). Simulations show that application of this algorithm is equal to using the on-off valve which has smaller effective area. Experimental results verify improvement in the position control performance.
Finally change of optimal gain values of 3-loop controller that is used with this algorithm is shown.
