A General Arthropod Joint Model and its Applications in Modeling Human Robotic Joints

Renghao Liang,Xiaowei Zheng,Sicong Zhang,Guanghua Xu,Kai Zhang,Min Li,Zhicheng Teng,Bo He

doi:10.1109/access.2021.3049469

Renghao Liang, Xiaowei Zheng + Show 6 more

Open Access

https://doi.org/10.1109/access.2021.3049469

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Abstract

Bearings are common rotational units, but these monocentric units do not realize high bio-imitability in exoskeleton robots. A common way to realize bionic motion is with an n-bar linkage mechanism within bearings, but the resultant joints can become complex. Herein, we propose a joint model based on the anatomy of grasshopper joints that consists of a pair of conjugate surfaces and a flexible connection body. An anatomical experiment involving crabs and lobsters reveals that the proposed joint model exists among crustaceans, which makes it a general joint structure for arthropods. After measuring the kinematic properties of crab and lobster joints, we have modified the joint model for robotics applications. An optimization algorithm is proposed for the design of the joint. A prototype of a bionic joint is fabricated and its kinematic characteristics are verified. The arthropod joint model is a promising mechanical unit in bionic robots.

Highlights

Wearable robotic exoskeletons have been researched extensively in the field of functional limb rehabilitation for many years, and most wearable devices are designed to mimic the motions of users [1]
The use of an n-bar linkage mechanism as a human joint exoskeleton has been researched to solve the problem of kinematic interference caused by a monocentric rotation mechanism, The associate editor coordinating the review of this manuscript and approving it for publication was Mohammad Alshabi
The basic exoskeleton model shows the fundamental drawbacks of existing rehabilitation devices, and the aim of this study is to propose a better form of a basic exoskeleton model

Summary

Introduction

Wearable robotic exoskeletons have been researched extensively in the field of functional limb rehabilitation for many years, and most wearable devices are designed to mimic the motions of users [1]. The most general model of a joint exoskeleton is a fixed-axis rotating hinge (Fig. 1, a). As the rotation axis of human joints is not constant [4]—i.e., it is polycentric—the monocentric rotation model causes inconsistencies between human limbs and the exoskeletons during movement. N-bar linkages are popular for facilitating path trajectories [5], and these models can replicate a specific motion of human limbs with a proper linkage design (Fig. 1, b). The use of an n-bar linkage mechanism as a human joint exoskeleton has been researched to solve the problem of kinematic interference caused by a monocentric rotation mechanism, The associate editor coordinating the review of this manuscript and approving it for publication was Mohammad Alshabi

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