Functional Evaluation of a Force Sensor-Controlled Upper-Limb Power-Assisted Exoskeleton with High Backdrivability.

Chang Liu,Naoya Ueda,Chi Zhu,Hongbo Liang,Peirang Li,Yasutaka Fujimoto

doi:10.3390/s20216379

Chang Liu, Naoya Ueda + Show 4 more

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https://doi.org/10.3390/s20216379

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Abstract

A power-assisted exoskeleton should be capable of reducing the burden on the wearer’s body or rendering his or her work improved and efficient. More specifically, the exoskeleton should be easy to wear, be simple to use, and provide power assistance without hindering the wearer’s movement. Therefore, it is necessary to evaluate the backdrivability, range of motion, and power-assist capability of such an exoskeleton. This evaluation identifies the pros and cons of the exoskeleton, and it serves as the basis for its subsequent development. In this study, a lightweight upper-limb power-assisted exoskeleton with high backdrivability was developed. Moreover, a motion capture system was adopted to measure and analyze the workspace of the wearer’s upper limb after the exoskeleton was worn. The results were used to evaluate the exoskeleton’s ability to support the wearer’s movement. Furthermore, a small and compact three-axis force sensor was used for power assistance, and the effect of the power assistance was evaluated by means of measuring the wearer’s surface electromyography, force, and joint angle signals. Overall, the study showed that the exoskeleton could achieve power assistance and did not affect the wearer’s movements.

Highlights

Owing to the accelerated aging of the world’s population, the average age of heavy-duty workers in environments such as construction sites, logistic centers, and nursing care facilities is steadily increasing.the development and adoption of power assistance devices to alleviate the burdens of these workers are becoming necessary and critical
Since the sEMG signals directly reflects the load on subject’s joint, our results suggest that the power assistance of the exoskeleton is effective to reduce the burden on the wearer’s muscles
The measurement experiments have verified that the subjects with exoskeleton have achieved not less than 80% of the workspace of without exoskeleton, which indicates that the workspace of our upper-limb exoskeleton can meet the demands of daily use

Summary

Introduction

The development and adoption of power assistance devices to alleviate the burdens of these workers are becoming necessary and critical. One such power assistance device is an exoskeleton, a mechanical structure that can be worn over the user’s body, and it can effectively reduce the wearer’s burden by transferring the load to itself. The research and development pertaining to exoskeletons has recently received significant attention [1]. An ideal exoskeleton should assist the wearer, be convenient to use, and not induce feelings of restraint or discomfort in the wearer. To ensure that the active joints of the exoskeleton possess

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