Non-local memory hysteresis in a pneumatic artificial muscle (PAM)

In a system using PAMs, a big research effort has been carried out to solve the control problem, in which the nonlinear dynamics of a PAM were left behind as a disturbance to that system. The inherent dynamics in a PAM is due to its constitutional materials which cause hysteresis during cyclic contraction/extension. Prior knowledge of the hysteresis behavior in a PAM may simplify the associated control system. In this paper, the hysteretic behavior of a PAM is investigated and the results show much similarity to the presliding regime in the friction of mechanical contacting elements. The PAM hysteresis is thus generalized and represented by a lumped-parameter model, which is useful for control design.