A Novel Twisted-Winching String Actuator for Robotic Applications: Design and Validation

TL;DR

This paper introduces a new twisted-string actuator with a winch mechanism that enhances stroke length and force transmission, offering a compact, adjustable, and precise actuation solution for robotics.

Contribution

It presents a novel integrated TSA-winch system with dynamic transmission ratio adjustment, improving upon traditional TSAs for robotic applications.

Findings

Achieves a wide range of transmission ratios

Demonstrates precise movement control

Provides increased force output

Abstract

This paper presents a novel actuator system combining a twisted string actuator (TSA) with a winch mechanism. Relative to traditional hydraulic and pneumatic systems in robotics, TSAs are compact and lightweight but face limitations in stroke length and force-transmission ratios. Our integrated TSA-winch system overcomes these constraints by providing variable transmission ratios through dynamic adjustment. It increases actuator stroke by winching instead of overtwisting, and it improves force output by twisting. The design features a rotating turret that houses a winch, which is mounted on a bevel gear assembly driven by a through-hole drive shaft. Mathematical models are developed for the combined displacement and velocity control of this system. Experimental validation demonstrates the actuator's ability to achieve a wide range of transmission ratios and precise movement control. We present performance data on movement precision and generated forces, discussing the results in the context of existing literature. This research contributes to the development of more versatile and efficient actuation systems for advanced robotic applications and improved automation solutions.