Controller design of mass flow rate loop for high-precision pneumatic actuator

Pneumatic cylinders will replace linear motors for high-speed and high-precision applications that require high force. A valve is an important part of the pneumatic driving system as it controls the pressure in the chambers and the pressure changes the stage position. However, valves present nonlinearity and time delay. To address the nonlinearity, we introduced a mass flow rate feedback. For a controller design, pole placement is often used. However, it is difficult to design a stable control system when the plant contains a delay. This study analyzes a condition on closed-loop poles for a stable control system when the plant contains a constant pure time delay. The results indicated that using the stable mass flow rate feedback improved the linearity of the plant for the pressure control system.