Antagonistic Bowden-Cable Actuation of a Lightweight Robotic Hand: Toward Dexterous Manipulation for Payload Constrained Humanoids

TL;DR

The paper addresses the challenge of achieving human-like dexterity in a lightweight humanoid hand suitable for payload-constrained robots. It introduces the Antagonistic Bowden-Cable-Driven Lightweight (ABCDL) hand, combining rolling-contact joints with antagonistic Bowden-cable actuation and a remote torso-mounted actuator to realize single-motor-per-joint control while keeping distal mass low. Key results show a distal hand mass of $236~\mathrm{g}$, fingertip forces exceeding $18~\mathrm{N}$, tip speeds around $200~\mathrm{mm/s}$, and robust manipulation including lifting a $25~\mathrm{kg}$ payload and maintaining trajectory fidelity under actuator perturbations, with a residual cable-length deviation of about $0.03~\mathrm{mm}$. The work demonstrates a practical route to high-DOF, high-force, anthropomorphic hands for humanoids with restricted payload budgets, and outlines future enhancements in thumb fidelity and rolling-contact coordination.

Abstract

Humanoid robots toward human-level dexterity require robotic hands capable of simultaneously providing high grasping force, rapid actuation speeds, multiple degrees of freedom, and lightweight structures within human-like size constraints. Meeting these conflicting requirements remains challenging, as satisfying this combination typically necessitates heavier actuators and bulkier transmission systems, significantly restricting the payload capacity of robot arms. In this letter, we present a lightweight anthropomorphic hand actuated by Bowden cables, which uniquely combines rolling-contact joint optimization with antagonistic cable actuation, enabling single-motor-per-joint control with negligible cable-length deviation. By relocating the actuator module to the torso, the design substantially reduces distal mass while maintaining anthropomorphic scale and dexterity. Additionally, this antagonistic cable actuation eliminates the need for synchronization between motors. Using the proposed methods, the hand assembly with a distal mass of 236g (excluding remote actuators and Bowden sheaths) demonstrated reliable execution of dexterous tasks, exceeding 18N fingertip force and lifting payloads over one hundred times its own mass. Furthermore, robustness was validated through Cutkosky taxonomy grasps and trajectory consistency under perturbed actuator-hand transformations.

Figures (12)

• Figure 1: Overview of the proposed Antagonistic Bowden-Cable-Driven Lightweight (ABCDL) Robotic Hand.
• Figure 2: Comparison of joint structures and actuation between the human hand and the proposed robotic hand.
• Figure 3: Kinematic structure of the fingers in the proposed robotic hand, including cable routing and joint configuration.
• Figure 4: Geometric definition of the joint design parameters and coordinate relationships for antagonistic cable actuation.
• Figure 5: Kinematic optimization of rolling radius $r_i$ for antagonistic cable actuation. (a) Optimized $r_i$ for a flexion–extension joint, determined across different combinations of $\kappa$ and $\beta$ over the full ROM. (b) Residual maximum absolute length deviation of the antagonistic cable pair, $\max(|\Delta c_f + \Delta c_e|)$, evaluated at the optimized $r_i$ in (a).