Development of a Compact Walking Assistive Robot for Exercise Promotion and Gait Training

Abstract: With the growing population of aged citizens, the number of people coping with walking disorders is increasing. To address this problem, various types of walking assistive robots were developed. However, most of these robots are heavy, bulky, and with poor practicability.In this study, we developed a compact walking assistive robot which can be used for exercise promotion and gait training for the able-bodied elderly. By assisting only the user’s ankle joint, the robot can assist the foot lift based on the stretch reflex mechanism, inform the user of the correct motion and timing, and guide them to achieve ideal walking. The proposed robot consists of cover, servo motor, torque limiter, control unit, adjustable straps, shoes, and pressure sensors. By 3D printing the cover with resin, the total weight is 1.2 kg with battery. In addition, to reduce noise, arc-shape springs made of soft materials were used instead of straight-shape spring, and these design parameters were calculated from theoretical equation. Walking parameters and control mode can be adjusted by graphical user interface application. For a control mode, we used a gait-adaptive method for ankle assistive robots to adapt to the user’s changing gait for providing more accurate walking assistance.Finally, we conducted a walking test to investigate the gait-adaptive accuracy and how user feels. Participants were required to wear robot and walk continuously for 30 strides (60 steps) with same trends. The gait-adaptive accuracy achieved high accuracy exceeding 95 % on average using a gait-adaptive method based on regression. In addition, the user felt a positive impression, which user feels an assist force and fun, and can walk smoothly etc., for proposed robot during walking. As a result, a series of evaluation experiments verified an effectiveness, finally concluded that the proposed robot could be used for exercise promotion and gait training. The advantages of the proposed robot are low cost, light weight and easy-to-use.

Keywords: Ankle Assistive Robot, Human-robot Interaction, System Integration, Human-centered Design

DOI: 10.54941/ahfe1004409

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