Mathematical Modeling of Combined Actuator for Rehabilitation Exoskeleton

This paper deals with the mathematical modeling of a lower limb rehabilitation exoskeleton with a combined actuator. The actuator consists of an electric actuator and a mechanical energy storage spring acting as a gravity compensator, which is used to create an auxiliary torque compensating part of the gravity load. A mathematical model is described and mathematical modeling of the trajectory motion of the leg of the exoskeleton with a combined drive under different characteristics of the mechanical energy storage is carried out. The trajectory motion is based on anthropomorphic gait, based on approximated data of human step video recordings. The simulation results confirm that the mechanical energy storage generates an auxiliary torque compensating part of the gravitational forces of the exoskeleton leg.