A Simulation-based Design of Ankle Assistive Robot for Tripping Prevention of Elderly People

Abstract

In this paper, a method to simulate the force required to prevent tripping of the elderly person during walking and to optimize the stiffness of the spring that are used in assist robot was proposed. For the simulation, Opensim was used to analyze the muscle force of the human musculoskeletal model (MM). The robot model was imported from a CAD file and integrated with the MM. In the MM provided by Opensim, the elderly model was represented by limiting the muscular strength. Force saturation was imposed on the maximal isometric force of the muscles involved in the movement of the ankle joint. In order to compensate for weakened muscle strength around ankle joint, path actuator that represents the tensile force of an assist robot in the simulation were added. Optimal tensile force that supports the movement of the ankle joint was determined by using a computed muscle control (CMC) tool provided at Opensim. The stiffness of the spring was optimized by using MATLAB optimization function based on the path actuator tensile force.