Reconfigurable Tendon-Driven Robots: Eliminating Inter-segmental Coupling via Independently Lockable Joints

2025-07-22

AI Summary

Tendon-driven robots face significant challenges—including strong inter-segment coupling, complex modeling, and actuation redundancy—when increasing segment count to enhance flexibility and workspace. To address these, this paper proposes a reconfigurable tendon-driven robot featuring a novel actively lockable/unlockable joint mechanism: once locked, joints maintain their state without continuous power, fully decoupling adjacent segments and enabling selective, independent actuation of target segments. Antagonistic tendons cooperatively control locking/unlocking states, while integrated kinematic and static modeling enables accurate system characterization. Simulation and experimental results validate the robot’s on-demand morphological and actuation-mode reconfiguration capability. A seven-joint prototype achieves dexterous navigation in complex environments using only six motors, substantially expanding its reachable workspace and reducing control dimensionality. This work establishes a new paradigm for high-DOF soft robots—offering enhanced efficiency, low power consumption, and simplified control.

Technology Category

• Intelligent Robots: Manipulation
• Planning, Routing, and Scheduling: Replanning and Plan Repair
• Computer Vision: Low Level & Physics-based Vision

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Systems and Infrastructure for Web, Mobile and WoT: Experiences and lessons learnt from Web-based algorithms and system deployments
• Search and Retrieval-Augmented AI: Agentic search

Abstract

With a slender redundant body, the tendon-driven robot (TDR) has a large workspace and great maneuverability while working in complex environments. TDR comprises multiple independently controlled robot segments, each with a set of driving tendons. While increasing the number of robot segments enhances dexterity and expands the workspace, this structural expansion also introduces intensified inter-segmental coupling. Therefore, achieving precise TDR control requires more complex models and additional motors. This paper presents a reconfigurable tendon-driven robot (RTR) equipped with innovative lockable joints. Each joint's state (locked/free) can be individually controlled through a pair of antagonistic tendons, and its structure eliminates the need for a continuous power supply to maintain the state. Operators can selectively actuate the targeted robot segments, and this scheme fundamentally eliminates the inter-segmental coupling, thereby avoiding the requirement for complex coordinated control between segments. The workspace of RTR has been simulated and compared with traditional TDRs' workspace, and RTR's advantages are further revealed. The kinematics and statics models of the RTR have been derived and validation experiments have been conducted. Demonstrations have been performed using a seven-joint RTR prototype to show its reconfigurability and moving ability in complex environments with an actuator pack comprising only six motors.

Problem

• Eliminate inter-segmental coupling in tendon-driven robots
• Reduce complex models and motors for precise control
• Enable selective actuation without continuous power supply

Innovation

• Lockable joints controlled by antagonistic tendons
• Eliminates inter-segmental coupling in tendon-driven robots
• Reduces motors needed via selective segment actuation