Time-Division Multiplexing Actuation in Tendon-Driven Arms: Lightweight Design and Fault Tolerance

TL;DR

This paper introduces TDMA for tendon-driven robotic arms, reducing actuator count while maintaining high torque, fault tolerance, and lightweight design, suitable for aerospace applications.

Contribution

It presents a novel hardware architecture and control algorithm for fault-tolerant, lightweight tendon-driven robots with significantly fewer actuators.

Findings

MuxArm weighs 2.17 kg and supports 10 kg load capacity.

End-effector accuracy reaches 1% of its length even with partial servo failure.

Trajectory planning reduces tendon load by up to 50%.

Abstract

Robotic manipulators for aerospace applications require a delicate balance between lightweight construction and fault-tolerant operation to satisfy strict weight limitations and ensure reliability in remote, hazardous environments. This paper presents Time-Division Multiplexing Actuation (TDMA), a practical approach for tendon-driven robots that significantly reduces actuator count while preserving high torque output and intrinsic fault tolerance. The key hardware employs a vertically-stacked rotational selection structure that integrates self-rotating TDM motors for rapid configuration, electromagnetic clutches enabling sub-0.1 second engagement, a worm gear reducer for enhanced load capacity and self-locking capability, and a dual-encoder system for precise, long-term positioning. Leveraging TDMA, the proposed MuxArm achieves a self-weight of 2.17 kg, supports an actuator driving capacity of 10 kg, and maintains end-effector accuracy up to 1% of its length, even under partial servo failure. Additionally, an actuation space trajectory planning algorithm is developed, enabling fault-tolerant control and reducing tendon load by up to 50% compared to conventional methods. Comprehensive experiments demonstrate MuxArm's robust performance in diverse settings, including free-space, cluttered, and confined environments.