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).

我们对SMA执行器的精确定位能力进行了实验研究，目的是评估SMA执行器在精密工程领域的实际适用性。为此，我们专注于定量评估SMA执行器的定位精度和最小步长。在测量定位跟踪误差的精度测试中，通过三种不同的位置控制方案来控制SMA执行器产生的位置：（1）仅使用滞后补偿器；（2）仅PID控制器；（3）使用具有磁滞补偿器的PID控制器。实验结果表明，三角形，正弦和方形参考输入的最小定位RMSE分别为0.0081％，0.0124％和1.1314％，可以通过将PID控制器与磁滞补偿器配合使用来实现。并且，对于全行程（FS）为约6.4mm（即，0.13％FS）的情况，观察到最小的增量和减量步长为8.2μm。