Robust control of pneumatic actuators based on dynamic impedance matching

Pneumatic actuators have many merits such as high power weight ratio, easy maintenance and handling, relatively simple technology and low cost, among other. But they are not commonly used in the area of precise servo control because of the compressibility, and many nonlinear characteristics such as dry friction between cylinder and piston make these actuators very sensitive to load variation. As a consequence, piston position and velocity are difficult to control accurately. The aim of the present study is to make pneumatic actuator robust to load variation, by application of dynamic impedance matching, which is the robust control method so that velocity (or force) output characteristics remain the same under load (or velocity) change. Simulation and experimental evaluation are given to confirm the effectiveness of the method.