Experimental Hysteresis Identification and Micro-position Control of a Shape-Memory-Alloy Rod Actuator

In order to exhaustively exploit the high-level capabilities of shape memory alloys (SMAs), they must be applied in control systems applications. However, because of their hysteretic inherent, dilatory response, and nonlinear behavior, scientists are thwarted in their attempt to design controllers for actuators of such kind.  The current study aims at developing a micro-position control system for a novel SMA rod actuator. To do so, the hysteretic behavior of the actuator was simulated in the form of a gray-box Wiener model. Based on the experimental training dataset obtained from the actuator, the hysteresis Wiener model was trained using a PSO algorithm. Afterwards that the identified hysteresis Wiener model was validated, the authors formed a model-in-the-loop (MIL) position control system. Next, a PSO algorithm was again set to find the best controller parameters regarding some performance criteria. At the end, implemented on the fabricated prototype (the experimental setup), the designed control system shared such excellent accuracy that makes the fabricated actuator amenable to micro-positioning applications.