Maneuverability of Impedance-Controlled Motion in a Human-Robot Cooperative Task System

This paper presents an evaluation of the maneuverability of impedance-controlled robot motion during a human-robot cooperative positioning task. The objectives of this study are to reveal the results of a quantitative evaluation of the maneuverability of robot motion and to investigate the relationship between the results of the quantitative evaluation and an operator’s higher-order brain activity. Control strategies for the robot that are adequate for human-robot interaction have not yet been explicitly determined because of the difficulty in evaluating the maneuverability of robot motion. First, we analyzed the time normalized position and force/torque trajectories to reveal the characteristics of human motion and performed subjective evaluations for three types of impedance-controlled robot motion, which were controlled using the following strategies: (i) ordinary impedance control, (ii) impedance control with virtual Coulomb friction involved in the robot motion, and (iii) impedance control with a trajectory guidance force. Second, to confirm the analysis results based on the observed trajectories, we investigated differences in the operator’s higher-order brain activity when using the different control strategies by using a functional near-infrared spectroscopy system. The experimental results confirmed the relationship between the analysis results of the control strategies, the motion of the operator, and higher-order brain activity. Consequently, the investigation conducted in this study is effective for evaluating the maneuverability of robot motion during a human-robot cooperative task.