Sensorless angle and stiffness control of antagonistic PAM actuator using reference set

This paper proposes a simultaneous control method for the angle and stiffness of joint in an antagonistic pneumatic artificial muscle (PAM) actuator system using only pressure measurements absence external force, clarifies allowable references PAM system. To achieve sensorless control, proposed estimates contraction forces unscented Kalman filter that employs detailed model Unlike previous methods, does not require any encoder force sensor to Experimental validations three scenarios confirm can simultaneously independently. Moreover, it is shown reference admissible set be used as indicator establish values by demonstrating covers experimentally obtained trajectories stiffness.