Design of a Fabric-based Soft Wearable Upper-limb Motion Assistive System

Neuromuscular diseases and joint disorders often lead to upper-limb motion impairments. However, the existing wearable robots are bulky and expensive, inadequate for daily motion assistance. To address this matter, a portable, comfortable, flexible and wearable upper-limb assistive system is developed based on lightweight flexible fabric, to assist shoulder and elbow motions. Firstly, shoulder abduction and elbow flexion actuators are designed based on the motion characteristics of the shoulder and elbow joints, and their theoretical analysis models are established. Inspired by the skin at the joints, the elbow actuator is equipped with corrugated folds to reduce mechanical resistance, and adapts the joint curvature through the curvature limiting layer. Then, the actuators are integrated into a garment, and tests on mechanical transparency and motion range are conducted, as well as load experiments and simulations of daily life tasks. Results show that the system has good mechanical transparency, and its motion range can meet the daily needs; in the load experiments, the activation levels of the middle deltoid muscle and the biceps brachii, decrease by 52.2% and by 54.0% separately; in the simulation of daily life tasks, the coordinated motion assistance provided by the system significantly decrease the muscle activation levels. The system exhibits good flexibility and portability, and can achieve mechanical transparency while providing the necessary motion assistance for daily life.