Variable impedance control with stiffness for human-robot cooperation system

This paper described a novel variable impedance control that include a stiffness coefficient for the human-robot cooperation. This control method changes not only a damping coefficient but also stiffness coefficient according to a process of tasks. For example, when a human positions an object nearby an environment with the purpose of installing it at the environment, the stiffness characteristic is helpful for avoiding a collision between the robot and environment and easy installation. A cooperative task to carry the object nearby the environment and then hold it close to the environment was performed to confirm the usefulness of the proposed control strategy. Experimental results show that the variable impedance control with stiffness is suitable for not only carrying and positioning tasks, but also various tasks which are contacting with the environment.