Modeling and Analysis of a Variable Stiffness Actuator for a Safe Home-based Exoskeleton

Abstract

In this paper, we modelled and analyzed a variable stiffness actuator-based exoskeleton which could provide optimal actuated elbow stiffness for those patients with a specific impairment of upper limbs. In this exoskeleton, a variable stiffness actuator is integrated for adjusting the actuated joint stiffness independently. Stiffness adjustment is realized based on a movable pivot to change the transmission ratio between the elastic elements and the output link. The characteristic of the elastic elements affects the performance of the variable stiffness actuator. Therefore, we established the model of the variable stiffness actuator and simulated its stiffness characteristics with different spring coefficients, preloads and damping respectively. We analyzed how those factors affect the characteristics of the proposed variable stiffness actuator. The performance of the variable stiffness actuator-based exoskeleton could be improved by properly choosing the spring parameters.