Position control of shape memory alloy actuated gripper

Shape memory alloys (SMA) are the class of stimulus responsive materials which are used as actuators because of the ability in recovering their predetermined shape when subjected to an appropriate thermal procedure. This shape recovery introduces a mechanical work that can be used to produce linear or rotational movements of a modular actuator. This work presents the investigation of control algorithms for position control of a shape memory alloy actuated gripper. The transfer function model of the SMA fiber actuator is determined from the experimental open loop response. Model based proportional integral (PI), pulse width pulse amplitude modulated proportional integral (PI-PWPAM) and internal model sliding mode controller (IM-SMC) controllers are designed. The performance of these controllers is simulated for position control. The results demonstrate that the IM-SMC performs well in tracking the desired response and provides faster response.