Chatter attenuation for pneumatic artificial rubber muscles

Abstract Pneumatic artificial rubber muscles (Parms) are similar to biological muscles as both act as springs. Stiffness varies with pressure for the Parm and with neural impulse for the biological muscle. As a Parm system is highly non linear, its classical control does not reveal to be totally indicated. Robust control techniques such as variable structure controls generating sliding modes are quite indicated. However, sliding mode control although robust generates chattering as the control switches across the sliding manifold. In this work, two controls are applied onto a robot driven by Parms in order to reduce this undesirable chatter. The first law is a generalised variable structure algorithm while the second one is a 2-sliding law, the “twisting” algorithm. Experimental results are presented and discussed.