Positioning Control of Pneumatic Drive Systems by using Disturbance Observer.

Abstract

Pneumatic drive systems have higher power/weight ratio. So, it is easy to make a compact and lightweight robot manipulator. On the other hand, compressibility of air and very large friction, which is caused by mechanical seal, worsen the performance of positioning for a pneumatic drive system. Therefore, our goal of this study is to propose a positioning control scheme for pneumatic drive systems. In the proposed control scheme, full state feedback control and the disturbance compensator, which is composed by a disturbance observer and integral control action, are used in order to eliminate the effects of compressibility and friction. Further more, to eliminate the delay of a pneumatic servo valve, we designed the electric motor-driven servo valve which can respond very quickly. The effectiveness of the proposed control scheme and electric motor-driven servo valves is shown through experiments. As a result, by using out this method, a pneumatic drive system can be positioned at arbitrary point as fast as an electric motor does.