An experimental study on precision positioning characteristics of shape memory alloy actuator

We perform the experimental study on the precision positioning capability of SMA actuators, with the aim of evaluating practical applicability of the SMA actuator to the field of precision engineering. For the aim, we focus on assessing the positioning accuracy and the minimum step-size of the SMA actuator quantitatively. In the accuracy test measuring the positioning tracking error, the position generated by the SMA actuator is controlled with three different position-control schemes: position-control with (1) only hysteresis compensator, (2) only PID controller, and (3) with PID controller with hysteresis compensator. The experimental results indicate that the smallest positioning RMSE of 0.0081%, 0.0124%, and 1.1314% for the triangular, sinusoidal, and square reference input, respectively, can be achieved by applying the PID controller with hysteresis compensator. And, the minimum incremental and decremental step-size is observed as 8.2 μm for the case that the full-stroke (FS) is about 6.4 mm (i.e., 0.13% FS).