Twisted String Actuators (TSAs) are widely used in robotics but suffer from a limited range of Transmission Ratio (TR) variation, restricting their efficiency under varying loads.To overcome this, we propose a novel lightweight, simple-structured Continuously Variable Transmission (CVT) mechanism for TSA utilizing Shape Memory Alloy (SMA) superelasticity. The CVT mechanism consists solely of a pair of highly lightweight superelastic SMA rods connecting the ends of twisted strings. These rods deform under external loads, adjusting the inter-string distance to enable continuous TR variation.We develop a comprehensive theoretical model that integrates three critical nonlinearities
Cite
@article{arxiv.2512.20342,
title = {Design and Modeling of a Simple-Structured Continuously Variable Transmission Utilizing Shape Memory Alloy Superelasticity for Twisted String Actuator},
author = {Chanchan Xu and Shuai Dong and Xiaojie Wang},
journal= {arXiv preprint arXiv:2512.20342},
year = {2025}
}