Position based impedance control based on pressure distribution for wearable power assist robots

Abstract

In this paper, a new impedance control method for wearable assist robots based 011 pressure distribution is proposed. Conventional power assist systems could not realize high power assist because they did not consider about the physical contacts between the user and robot. Also, these systems assisted only for simple joints such as knee, elbow, limb and so on. I11 order to achieve higher power assist lor multiple joints such as shoulder and waist, it is desirable to consider the contact condition directly instead of torque that was used in conventional methods. The authors propose a position based impedance control system using pressure distribution between the user and robot. By using a pseudo torque calculated by pressure distribution, the impedance controller can be expected to reduce the dangerous contact pressure efficiently. I11 this paper, power assist 011 the multiple joints are assumed: forward-backward bending movements of the upper half part of the body. A structure of the assist robot is determined based 011 analysis of human movements. By applying determined robot model 011 simulations, the proposed impedance control method is evaluated by comparing contact pressure to conventional methods.