Gray-box identification of McKibben pneumatic artificial muscle using interpolation of load-dependent parameters

This paper presents a hybrid nonlinear model of a McKibben pneumatic artificial muscle (PAM) actuated via a proportional directional control valve, taking load changes into account. We assume that model parameters dependent on the load are ones affecting on steady-state behaviors of the PAM when a step command signal is input to the valve. For such a model, this paper proposes an identification procedure that includes interpolation of the load-dependent parameters. Finally, we validate how much the presented model simulates the real behaviors of the practical PAM system, illustrate that the assumption is rational in this identification setting, and confirm that the proposed identification procedure is rational.