Modeling and control of a curved pneumatic muscle actuator for wearable elbow exoskeleton

A novel curved pneumatic muscle based rotary actuator for the wearable elbow exoskeleton with joint torque control is proposed. Compared to the general utilization of the pneumatic muscle actuator (PMA) in a rotary joint, this novel structure weakens coupling relationship between the output torque/force and contacting displacement of the PMA so that it can be easily utilized in the tele-robotics with torque/force-feedback or the exciting application in rehabilitation for a wide range. By referred to two physical models, namely beam model and membrane model, the mechanics properties of this mechanical structure is analyzed. In addition a hybrid fuzzy controller composed of bang–bang controller and fuzzy controller is employed for output torque control with high accuracy as well as fast response. In a series of experiments, the actuator exhibits both good static and dynamic performances that well validated the models and control strategy.