A Variable Stiffness Exosuit for Walking Assistance

Robotic exoskeleton takes an important role in walking assistance for subjects with lower extremity impairment. However, most of the existing robotic exoskeletons are bulky and complicated in the mechanical structure, placing a large load on the wearer. In this paper, a soft exosuit with twisted string actuators (TSAs) is designed for walking assistance. The analytic model of the TSA is derived to prove its characteristic of variable stiffness, benefited from which, flexible and compliant assistive torque can be generated to knee joints whilst walking. Furthermore, a human-robot coupling dynamic model is established, and an admittance control strategy is utilized to improve the trajectory tracking performance. Finally, simulations are conducted to verify the proposed robot system.