Human Mimetic Forearm Design with Radioulnar Joint using Miniature Bone-Muscle Modules and Its Applications

TL;DR

This paper presents a human-like forearm design with a radioulnar joint using miniature bone-muscle modules, enabling realistic motions and applications in robotics.

Contribution

It introduces a novel miniaturized muscle module that functions as both muscle and bone, mimicking human forearm structure and motion.

Findings

Successfully developed a forearm with human-like joint and motion capabilities

Enabled skillful motions such as soldering and badminton swinging

Demonstrated improved mimicry of human forearm functions

Abstract

The human forearm is composed of two long, thin bones called the radius and the ulna, and rotates using two axle joints. We aimed to develop a forearm based on the body proportion, weight ratio, muscle arrangement, and joint performance of the human body in order to bring out its benefits. For this, we need to miniaturize the muscle modules. To approach this task, we arranged two muscle motors inside one muscle module, and used the space effectively by utilizing common parts. In addition, we enabled the muscle module to also be used as the bone structure. Moreover, we used miniature motors and developed a way to dissipate the motor heat to the bone structure. Through these approaches, we succeeded in developing a forearm with a radioulnar joint based on the body proportion, weight ratio, muscle arrangement, and joint performance of the human body, while keeping maintainability and reliability. Also, we performed some motions such as soldering, opening a book, turning a screw, and badminton swinging using the benefits of the radioulnar structure, which have not been discussed before, and verified that Kengoro can realize skillful motions using the radioulnar joint like a human.