A New Approach to Modeling Hysteresis in a Pneumatic Artificial Muscle Using The Maxwell-Slip Model

Abstract—Two main challenges in using a pneumatic artificial muscle (PAM) actuator are the nonlinearity of pneumatic system and the nonlinearity of the PAM dynamics. The latter is compli-cated to characterize. In this paper, a Maxwell-slip model used as a lumped-parametric quasi-static model is proposed to cap-ture the force/length hysteresis of a PAM. The intuitive selection of elements in this model interprets the unclear, but blended con-tributing causes of the hysteresis very well, which are assumed to originate from the dry friction of the double helix weaving of the PAM braided shell, the friction of the weaving and the bladder, the elasticity of the bladder and/or the deformation of the conical parts of a PAM close to the end caps. The obtained model is simple, but physically meaningful and easy to handle in terms of control. Index Terms—Hysteresis, modeling, nonlinear systems, pneu-matic systems. I