Time-Division Multiplexing Actuation in Tendon-Driven Arms: Lightweight Design and Fault Tolerance
For aerospace robotics, this work provides a lightweight, fault-tolerant manipulator design that balances weight constraints with reliability.
The paper introduces Time-Division Multiplexing Actuation (TDMA) for tendon-driven robots, reducing actuator count while maintaining high torque and fault tolerance. The MuxArm prototype achieves 2.17 kg weight, 10 kg load capacity, 1% accuracy, and 50% reduction in tendon load under partial servo failure.
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.