A portable AFO solution for pneumatic actuator with cable tendon mechanism to assist ankle dorsiflexion

Frontiers in Bioengineering and Biotechnology

Bioengineering and Biotechnology

Ling-Fung Yeung¹  Junming Wang¹  Jing Shu¹  Chengpeng Hu¹  Raymond Kai-Yu Tong¹  Yujie Su¹  Zheng Li² 

[1] Department of Biomedical Engineering, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China;Department of Surgery, The Chinese University of Hong Kong, Shatin, Hong Kong SAR, China;

关键词: ankle-foot orthosis;    pneumatic actuator;    stroke rehabilitation;    wearable robots;    assistive robots;   

DOI  :  10.3389/fbioe.2023.1227327

 received in 2023-05-23, accepted in 2023-10-06,  发布年份 2023

来源: Frontiers

【 摘 要 】

The limited portability of pneumatic pumps presents a challenge for ankle-foot orthosis actuated by pneumatic actuators. The high-pressure requirements and time delay responses of pneumatic actuators necessitate a powerful and large pump, which renders the entire device heavy and inconvenient to carry. In this paper, we propose and validate a concept that enhances portability by employing a slack cable tendon mechanism. By managing slack tension properly, the time delay response problem of pneumatic actuators is eliminated through early triggering, and the system can be effectively controlled to generate the desired force for dorsiflexion assistance. The current portable integration of the system weighs approximately 1.6 kg, with distribution of 0.5 kg actuation part on the shank and 1.1 kg power system on the waist, excluding the battery. A mathematical model is developed to determine the proper triggering time and volumetric flow rate requirements for pump selection. To evaluate the performance of this actuation system and mathematical model, the artificial muscle’s response time and real volumetric flow rate were preliminarily tested with different portable pumps on a healthy participant during treadmill walking at various speeds ranging from 0.5 m/s to 1.75 m/s. Two small pumps, specifically VN-C1 (5.36 L/min, 300 g) and VN-C4 (9.71L/min, 550 g), meet our design criteria, and then tested on three healthy subjects walking at normal speeds of 1 m/s and 1.5 m/s. The kinematic and electromyographic results demonstrate that the device can facilitate ankle dorsiflexion with a portable pump (300–500 g), generating sufficient force to lift up the foot segment, and reducing muscle activity responsible for ankle dorsiflexion during the swing phase by 8% and 10% at normal speeds of 1 m/s and 1.5 m/s respectively. This portable ankle robot, equipped with a compact pump weighing approximately 1.6 kg, holds significant potential for assisting individuals with lower limb weakness in walking, both within their homes and in clinical settings.

【 授权许可】

Unknown   
Copyright © 2023 Wang, Shu, Su, Hu, Yeung, Li and Tong.