Lead me by the hand: Evaluation of a direct physical interface for nursing assistant robots

When a user is in close proximity to a robot, physical contact becomes a potentially valuable channel for communication. People often use direct physical contact to guide a person to a desired location (e.g., leading a child by the hand) or to adjust a person´s posture for a task (e.g., a dance instructor working with a dancer). Within this paper, we present an implementation and evaluation of a direct physical interface for a human-scale anthropomorphic robot. We define a direct physical interface (DPI) to be an interface that enables a user to influence a robot´s behavior by making contact with its body. Human-human interaction inspired our interface design, which enables a user to lead our robot by the hand and position its arms. We evaluated this interface in the context of assisting nurses with patient lifting, which we expect to be a high-impact application area. Our evaluation consisted of a controlled laboratory experiment with 18 nurses from the Atlanta area of Georgia, USA. We found that our DPI significantly outperformed a comparable wireless gamepad interface in both objective and subjective measures, including number of collisions, time to complete the tasks, workload (Raw Task Load Index), and overall preference. In contrast, we found no significant difference between the two interfaces with respect to the users´ perceptions of personal safety.