Design and Validation of a Vision-Integrated Multi-Hinge Exosuit for Dorsiflexion Assistance: A Feasibility Study With Healthy Individuals

Exosuits play an essential role in facilitating rehabilitation training for patients with functional impairments. However, the safety of human-exosuit interactions and their adaptability to varied environments are crucial challenges that hinder their transition from laboratory prototypes to practical real-world applications. This study presents an innovative active exosuit designed to correct foot drop, characterized by its safe interactive performance and terrain daptability. Regarding safe human-exosuit interaction, meticulous design of the dimensions of hinge module ensures that, upon contact between the hinges, the driving rope reaches its maximum contraction length, thereby mechanically safeguarding against excessive dorsiflexion of the ankle joint by preventing further stretch. In terms of adaptability to various terrains, a visual system capable of terrain recognition has been integrated, enabling a seamless transition between control modes based on the detected terrain, achieving a recognition accuracy of 99.1% through the Transformer in Transformer (TNT) algorithm. To quantify the effect of the exosuit in correcting drop-foot, five healthy participants with artificially induced impairment were recruited to participate in the experiment. The experimental results revealed that the peak of the plantarflexion angle was decreased by 21.3%, 26.0%, and 46.5%, respectively, with the assistance of an exosuit when walking at the terrains of level ground (LG), upramps (UR), and upstairs (US). The root mean square (RMS) of the electromyography (EMG) signals of the tibialis anterior (TA) muscle was reduced by 26.9%, 32.5%, and 20.2%, respectively. These initial results demonstrate that the exosuit can effectively assist dorsiflexion at different terrains. Note to Practitioners—This paper has presented the design and evaluation of a soft exosuit equipped with multiple hinges and a vision system, which offers dorsiflexion assistance to improve ground clearance across various terrains. The multi-hinge structure facilitates effective assistance force transmission and acts as a mechanical limiter, preventing damage to the ankle joint from overstretching the Bowden cable due to control errors. The vision subsystem enables precise terrain recognition, facilitating tailored assistance based on the current terrain conditions. Moreover, a position-based control strategy is adopted based on the reference trajectory measured from the healthy side, enabling the exosuit to adapt to three terrains: LG, UR, and US. This work has the potential to advance the development of exosuits for practical applications significantly.