A Highly Integrated Shape Memory Alloy Actuator With Precision Real-time Self-sensing Control

In recent years, there has been significant advancement in the technological development of shape memory alloy (SMA) actuators, resulting in their increased maturity and wider applicability. Concurrently, the industry’s demand for compact, rapid-response actuators with high precision has seen a notable rise. In light of this, this study presents a novel SMA actuator utilizing Ni-Ti shape memory alloy (Ni-Ti SMA) wire, driven by the concept of SMA wire heating-induced contraction. The proposed actuator serves a dual purpose: measuring the intrinsic self-sensing attributes of the SMA wire and accurately ascertaining displacement alterations through the phase transition of the SMA wire, thereby precisely determining positional changes. By capitalizing on the resistance-displacement mapping relationship during the SMA wire’s phase transformation, autonomous self-sensing control is achieved without the need for external sensors. To meet the imperatives of rapid response, superior precision, and minimal form factor for the SMA wire, the actuator is ingeniously integrated to incorporate an auxiliary position sensor and a self-resetting loading mechanism. This integration significantly downsizes the overall dimensions of the SMA actuator, aligning it with the criteria of compactness while retaining performance.