Design and Implementation of Human-robot Interaction System with Variable Stiffness for Exoskeleton

At present, the connection mechanism between various exoskeleton robots and human body widely adopts the way of rigid fixed strap connection, which greatly affects the user’s wearing experience in the case of long time wearing and intense exercise. Therefore, this paper proposes an effective intelligent variable stiffness constraint system, which can increase the use’s motion flexibility and interactive comfort when wearing the exoskeleton, and has important application value. Firstly, the model of variable stiffness system (passive and active) is established. The dynamic simulation of the passive scheme was carried out, and the relationship between the human body velocity and the centrifugation of the turntable teeth was analyzed. The basic design principle was verified. System stiffness was 10.66g. mm/deg in the normal stable motion state, and the stiffness of the motion mode was transformed into rigid interaction. Secondly, the mechanical analysis and simulation were carried out to optimize the structure of the stressed parts. For the active scheme, the main work is to control the motor and verify the feasibility of the principle. The control system of the motor is built and the control circuit is set up. The range of stiffness of the whole system is wider than that of the passive one, from 70g/mm to 100g/mm. Finally, an experimental prototype was built to verify the connection stability on the actual exoskeleton, and the theoretical feasibility of each scheme was verified through independent experiments.