Variable impedance control with regard to working process for man-machine cooperation-work system

This paper presents a novel strategy of adjusting impedance parameters of a robot's end effector in a man-machine cooperation-work. In the proposed strategy, the impedance parameters are settled with regard to a working process of a human operator that is identified using a passivity index and an extreme value of force applied by the human operator. This approach enables to perform the cooperation-work with a robot easily. In order to confirm the usefulness of the strategy, the cooperation-work to which the robot's end effector is moved in the horizontal plane was performed. It is shown that the proposed strategy gives the manipulator a better characteristic than the invariable impedance control and the conventional variable impedance control. Furthermore, by a subjective evaluation test performed to subjects, the proposed control strategy is evaluated better than the other ones. Experimental results illustrate that the proposed control strategy for the robot is suitable for the cooperation-work.