Hysteresis modeling and trajectory tracking control of the pneumatic muscle actuator using modified Prandtl-Ishlinskii model

The pneumatic muscle actuator (PMA) has attracted extensive attentions from both industrial and academic fields due to its high power/weight ratio and significant compliance. However, on the one hand the inherent hysteresis nonlinearity has high influence on the accuracy of trajectory tracking control of PMA, and on the other hand a system actuated by PMAs is at a high cost. This paper presents a modified Prandtl-Ishlinskii (MPI) model for the asymmetric hysteresis characterization and compensation of the PMA using fast switching valves. By using the Levenberg-Marquardt (L-M) method, the parameters in the MPI model are identified. To compensate the nonlinear length/pressure hysteresis and reduce the cost, a cascade control scheme using fast switching valves based on the inverse MPI model is developed to realize the trajectory tracking control. The experimental result shows the effectiveness of the proposed control scheme on compensating the asymmetric length/pressure hysteresis of the PMA.