Design of an impact drive actuator using a shape memory alloy wire

This paper introduces an impact drive mechanism (IDM) that utilizes the rapid contraction property of shape memory alloy (SMA) wire. In this study, possible structures for an SMA-wire-based IDM actuator are investigated, and a prototype actuator comprising a main body, an inertia body, an SMA wire, and a bias spring is developed. To verify the applicability of the prototype actuator as a positioning device, driving experiments were conducted under various conditions. The experimental results demonstrated that the prototype actuator enables bidirectional step-like movement with several step sizes by changing the profile of applied voltage, such as amplitude, duty cycle, and frequency. In addition, we developed PI-controller-based position control systems by using these three parameters as control input; the control characteristics and potential applications of each method were discussed. These results implied that the SMA-wire-based IDM actuator has the potential to be used as a new linear actuator in sub-millimeter order driving.