Research on the position control of a 1-DoF set-up powered by pneumatic muscles

Abstract

A one-degree-of-freedom set-up driven by pneumatic muscles was designed and built in order to research the applicability of pneumatic artificial muscles in industrial applications, especially in wearable robots such as exoskeletons. The experimental set-up is very non-linear and very difficult to control properly. As a reference, an enhanced PID controller was designed. At the same time, a robust controller H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> and a sliding-mode controller based on an observer were designed and implemented. After that, a new position controller based on an internal pressure loop for each pneumatic muscle was tuned up. Firstly, this paper presents the experimental set-up and the system's linear models. After that, it summarizes the enhanced PID controller, H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">infin</sub> controller and the sliding-mode controller that have been designed. Then, it focuses on the position controller based on the internal pressure loops. Finally, the controllers are compared by means of experimental results.