CRAFT: A Tendon-Driven Hand with Hybrid Hard-Soft Compliance

TL;DR

The CRAFT hand is a cost-effective, tendon-driven anthropomorphic robotic hand with hybrid compliance, enhancing contact-rich manipulation, strength, and endurance while maintaining repeatability and affordability.

Contribution

This work introduces a novel hybrid hard-soft compliant design for a tendon-driven robotic hand, improving performance and cost-effectiveness over existing designs.

Findings

Improved strength and endurance in structural tests.

Enhanced handling of fragile and low-friction objects.

Achieved full grasp coverage in the Feix taxonomy.

Abstract

We introduce CRAFT hand, a tendon-driven anthropomorphic hand with hybrid hard-soft compliance for contact-rich manipulation. The design is based on a simple idea: contact is not uniform across the hand. Impacts concentrate at joints, while links carry most of the load. CRAFT places soft material at joints and keeps links rigid, and uses rollingcontact joint surfaces to keep flexion on repeatable motion paths. Fifteen motors mounted on the fingers drive the hand through tendons, keeping the form factor compact and the fingers light. In structural tests, CRAFT improves strength and endurance while maintaining comparable repeatability. In teleoperation, CRAFT improves handling of fragile and low-friction items, and the hand covers 33/33 grasps in the Feix taxonomy. The full design costs under $600 and will be released open-source with visionbased teleoperation and simulation integration. Project page: http://craft-hand.github.io/