Two-Degree-of-Freedom Flow Rate Control for Pneumatic Valves using Fast Response Flow Meter

抄録

High-precision and high-speed tracking position control with a large stroke is required for manufacturing equipment. To this end, this study aimed to utilize pneumatic cylinders for such equipment owing to their desirable properties such as high-power-to-weight ratio, low cost, and low heat exhaust. However, there are many challenges in achieving high-precision and high-speed tracking position control with pneumatic cylinders. One challenge is to address the varying dead zones of valves. In this paper, we propose a mass flow rate control system comprising a tuned inverse model of a valve and a two-degree-of-freedom (2-DOF) structure using a fast-response flowmeter. While conventional mass flow rate control based on the feedforward structure cannot address the varying dead zone, the proposed system can compensate for it using the tuning strategy and feedback structure. Furthermore, the proposed method needs less time and effort than the conventional one to develop the inverse model. Experimental results show the effectiveness of the proposed method and indicate that the tuned inverse model reduces the error immediately and that the feedback structure removes the remaining error. As the proposed method can remove the nonlinearity in the mass flow rate loop, we expect that it to improve pressure control performance and position control performance.