sEMG-Driven Assistive Control of a Modular Exoskeleton With Double-Tendon-Sheath Variable Stiffness Actuator

Exoskeletons play a huge role in human body enhancement and physical rehabilitation. In this paper, a new modular exoskeleton driven by double-tendon-sheath variable stiffness actuator (DTS-VSA) is designed to achieve effective human power assistance. The modular and variable stiffness structure of exoskeleton enable the adaptation to different human joint, improving the characteristics of physical human-robot interaction. The DTS-VSA is designed based on the pulley-cable-spring preloading principle and tendon sheath transmission, and its stiffness model is developed through quasi-static force balance analysis. To realize coordinated and active power argumentation, a fuzzy adaptive assistive controller integrated with human joint torque and stiffness estimation is proposed based on surface electromyography. Feasibility is experimentally verified via three typical load-carrying experiments and ten volunteers. The experimental results show that the average assistance efficiencies of elbow motion and knee motion in different experiment conditions are higher than 44.72% and 38.41%.