All-Fabric Bi-directional Actuators for Multi-joint Assistance of Upper Limb

According to clinical studies, upper limb robotic suits are vital to reduce therapist fatigue and accelerate patient rehabilitation. Soft pneumatic actuators have drawn increasing attention for the development of wearable robots due to their low weight, flexibility, and high power-to-weight ratio. However, most of current actuators were designed for the flexion assistance of a specific joint, and that for joint extension requires further investigation. Furthermore, designing an actuator for diverse working scenarios remains a challenge. In this paper, we propose an all-fabric bi-directional actuator to assist the flexion and extension of the elbow, wrist, and fingers. A mathematical model is presented that predicts the deformation and guides the design of the proposed bi-directional actuator. To further validate the applicability and adaptability of the proposed actuator for different joints, we developed a 3-DOF soft robotic suit. Preliminary results show that the robotic suit can assist the motion of the elbow, wrist, and finger of the subject.