Tap and push: Assessing the value of direct physical control in human-robot collaborative tasks

In this paper, we compare a touch-based human-to-robot command scheme with traditional button commands in a series of human-robot collaborative assembly tasks. We find a mapping between command style and task outcome that depends on task complexity and is influenced by robot “feel.” In our direct touch-based scheme, the user commands the robot through direct physical contact by tapping and pushing the robot. With a small, compliant desktop robot and a simple, scripted, bolt insertion task, button commands performed slightly better than direct physical commands in quantitative task performance metrics and qualitative user preference. In a second study with a human-scale, stiffer robot arm, physical commands performed better than button commands in a more complex and less scripted bolt insertion task, which greatly outperformed using buttons in a cooperative positioning task. We conclude that commanding a robot through direct force-transmitting contact can decrease task completion time, aid in teamwork, and improve user experience in appropriately chosen tasks. We achieve our haptic commands using only robot position sensors, demonstrating that direct, intuitive physical command is an option for existing position-controlled industrial robots.