Closed-loop position control of artificial muscles with a single integral action: Application to robust positioning of McKibben artificial muscle

Artificial muscles constitute a large class of non-linear actuators characterized by their own stiffness and damping. We analyze in the case of an axial contraction artificial muscle the relevance of a single integral action closed-loop controller. The basic idea of our approach consists in taking advantage of artificial muscle own stiffness and damping in order to substitute for a classic PID-controller an I-controller with as a consequence only one parameter to tune. Step and tracking responses performed with a pneumatic textile-braided McKibben muscle are reported showing the practical efficiency of the method to combine accuracy and load robustness performances.