Optimal variable impedance control for a robot and its application to lifting an object with a human

This paper describes a control method of a robot cooperating with a human. A task in which a robot and a human move an object cooperatively is considered To develop the force controller of the robot, the characteristics of human arm are investigated. The arm is forced to move along a trajectory in the experiment and the exerted force and the displacement are analyzed. It is found that the force characteristics of the human arm is regarded as an optimal damper with minimizing a cost function. Then, the model is implemented to a robot and the cooperation of the robot and a human operator is examined. The effectiveness of the derived model is evaluated and the experimental results show that the human moves the object supported by the robot with a minimum jerk trajectory. Next, the proposed control method is applied to a task in which a human and a robot lift an object cooperatively. The results show the effectiveness of the proposed control method.