Beam balancing ball driven by shape memory alloy: prospective actuator for stabilised control

Abstract

An alternative actuation mechanism is applied to the most sought after control laboratory system - the ball on beam. The system is driven by antagonistic shape memory alloy (SMA) wires which are engaged to play the role of both sensing and actuation in closed loop. The control objective is to govern the position of the ball on the beam. The angular altitude of the beam is varied by shifting the lateral position of the beam, through control of the smart actuator's angular acceleration. The focus is to study the use of SMA for systems with complex dynamics. A discrete sliding mode controller is implemented which requires no detailed information about the constitutive model of SMA. The differential resistance of the antagonistic SMA wires measured during actuation is utilized as the sensing signal. The innovation in this work is direct feedback of the measured signal which is facilitated by a specially designed signal processing electronics. The performance of the self-sensing under actuated system is illustrated through real time position control.