Design of a SMA-based soft composite structure for wearable rehabilitation gloves

Qiaolian Xie; Qiaoling Meng; Wenwei Yu; Zhiyu Wu; Rongna Xu; Qingxin Zeng; Zhongchao Zhou; Tianyi Yang; Hongliu Yu

doi:10.3389/fnbot.2023.1047493

Design of a SMA-based soft composite structure for wearable rehabilitation gloves

Front Neurorobot. 2023 Feb 10:17:1047493. doi: 10.3389/fnbot.2023.1047493. eCollection 2023.

Authors

Qiaolian Xie^{1

2

3}, Qiaoling Meng^{1

2}, Wenwei Yu^{3

4}, Zhiyu Wu^{1

2}, Rongna Xu^{1

2}, Qingxin Zeng^{1

2}, Zhongchao Zhou³, Tianyi Yang³, Hongliu Yu^{1

2}

Affiliations

¹ Institute of Rehabilitation Engineering and Technology, University of Shanghai for Science and Technology, Shanghai, China.
² Shanghai Engineering Research Center of Assistive Devices, Shanghai, China.
³ Department of Medical Engineering, Chiba University, Chiba, Japan.
⁴ Center for Frontier Medical Engineering, Chiba University, Chiba, Japan.

Abstract

The combination of smart soft composite structure based shape memory alloy (SMA) and exoskeleton technology has the advantages of light weight, energy saving, and great human-exoskeleton interaction. However, there are no relevant studies on the application of SMA-based soft composite structure (SSCS) in hand exoskeletons. The main difficulty is that directional mechanical properties of SSCS need to comply with fingers movement, and SSCS can deliver enough output torque and displacement to the relevant joints. This paper aims to study the application of SSCS for wearable rehabilitation gloves and explore its bionic driving mechanism. This paper proposes a soft wearable glove (Glove-SSCS) for hand rehabilitation actuated by the SSCS, based on finger force analysis under different drive modes. The Glove-SSCS can support five-finger flexion and extension, weighs only 120 g, and adopts modular design. Each drive module adopts a soft composite structure. And the structure integrates actuation, sensing and execution, including an active layer (SMA spring), a passive layer (manganese steel sheet), a sensing layer (bending sensor) and connection layers. To obtain a high-performance SMA actuators, the performance of SMA materials was tested in terms of temperature and voltage, temperature at the shortest length, pre-tensile length and load. And the human-exoskeleton coupling model of Glove-SSCS is established and analyzed from force and motion. The results show that the Glove-SSCS can realize bidirectional movements of fingers flexion and extension, with ranges of motion are 90-110° and 30-40°, and their cycles are 13-19 s and 11-13 s. During the use of Glove-SSCS, the temperature of gloves is from 25 to 67°C, and the surface temperature of hands is from 32 to 36°C. The temperature of Glove-SSCS can be kept at the lowest temperature of SMA operation without much impact on the human body.

Keywords: SMA actuator; hand exoskeleton; shape memory alloys (SMA); soft composite structure; soft exoskeleton.

Grants and funding

The authors gratefully acknowledged the financial supports by National Key R&D Program of China (Grant No. 2018YFC2001501), National Natural Science Foundation of China (Grant No. 61803265), Shanghai Foundation for Development and Technology, China (Grant No. 20S31905400), and the program of China Scholarships Council (Grant No. 202208310171).