VARIABLE IMPEDANCE CONTROL BASED ON ESTIMATION OF HUMAN ARM STIFFNESS FOR HUMAN-ROBOT COOPERATIVE TASK : Human-Robot Cooperative Calligraphic Task

Abstract

This paper presents a novel variable impedance control method for a human-robot cooperative task. There is a possibility that an impedance control system based on a positioning control of a robot with time delay of the robot and a human operator becomes unstable, when stiffness of a human arm is increased in the human-robot cooperative task. A proposed variable impedance controller varies a viscosity coefficient of the robot in proportion to an estimated value of the stiffness of the tip of the human arm. A proposed variable impedance control makes the human-robot cooperative system stable and the cooperative task easy.