Multiple robot / single human interaction: effects on perceived workload

This paper presents results from a user evaluation of a real multiple robot system in which the human’s perceived workload and performance were measured. Participants completed tasks with one, two, and four real heterogeneous mobile ground-based robots for indoor material transportation tasks. Twelve participants completed four trials of each task over two days. Generally speaking, little difference was found between the one and two-robot tasks; however perceived workload significantly increased while performance decreased during the four-robot task. A correlation analysis found that perceived workload increased as the number of commands (in total and by command type) and completion times increased. The highest number of accidents and user errors occurred during the four-robot task. In order to increase the number of robots a single human can supervise, the human must be provided with capabilities that reduce the number of required commands while also optimizing the human’s interactions with the robots. Index terms – human-robotic interaction, perceived workload, NASA Task Load Index, multiple mobile robots