Control-Free Mechanical Oscillator Powered by Shape Memory Alloys

Shape Memory Alloy (SMA) based actuators have been commonly used in applications that require being compact and lightweight. In this paper, the inherent stiffness of a flexure-based linear guide is used to create a bias-spring SMA actuator which further reduces the work weight density of such a class of actuator. Using a flexure-based magnetic latch system, the SMA actuator behaves as a mechanical oscillator that requires no electronics or control strategy. A thermal model is presented and validated such that the mechanical oscillator can be easily sized for the required application. A working prototype, measuring 60 mm x 50 mm x 10 mm in dimension weighing 10.2 g, is showcased in this work. This concept would be ideal for bio-mimetic mobile robots such as inchworm robots.