Force sensorless power assist controller design of transferring assist robot

This paper proposed a force sensorless power assist control methodology for transferring assist robot, where operation force of the nurse applying to the nursing lift is estimated using a disturbance observer. In order to improve estimation performance, a position information based disturbance observer is applied, in which no differentiators are needed to calculate acceleration for the system. As for the power assist algorithm, a position control-based power assist system is applied, where position reference for the nursing lift is generated based on an impedance control method using assist force calculated by the estimated force of the nurse. The effectiveness of the proposed power assist system has been verified by experiments using a prototype of a nursing lift.