Bidirectional Double-Spring Pneumatic Artificial Muscle With Inductive Self-Sensing

• Published in: IEEE robotics and automation letters 2023-12, Vol.8 (12), p.8160-8167
• Main Authors: Cho, Yeonha, Kim, Woojong, Park, Hyunkyu, Kim, Jung, Na, Youngjin
• Format: Article
• Language: English
• Subjects: Actuation; Actuator design; Actuators; Artificial muscles; Closed loops; Control; Design parameters; Elongation; Force; Inductance; Latex; learning for soft robots; modeling; Robot sensing systems; soft robot materials and design; Soft robotics; Soft sensors; soft sensors and actuators; Springs; Wearable robots; Wearable technology
• ISSN: 2377-3766; 2377-3766
• DOI: 10.1109/LRA.2023.3326660

This study proposes a bidirectional double-spring pneumatic artificial muscle (PAM) with inductive self-sensing for wearable robotic devices. The actuator structure, composed of commercially available latex and springs, enables a low-cost and consistent manufacturing process. Springs, which serve as the skeleton of the actuator, were used to increase the stability and stiffness of the structure, as well as to embed a self-sensing ability using the inductance of the spring. The actuator design parameters were selected through simulations to prevent buckling while achieving a notable actuation performance. The bidirectional force characteristics of the actuator were evaluated through quasi-static experiments, and the inductance-based length-sensing performance was validated during both contraction and elongation. The need for self-sensing in bidirectional actuation was emphasized through closed-loop length control. The proposed actuator can potentially enable the development of lightweight and efficient wearable robotic devices with improved sensing and actuation capabilities.