  In this paper, we propose a novel method for underwater robot-to-human
communication using the motion of the robot as "body language". To evaluate
this system, we develop simulated examples of the system's body language
gestures, called kinemes, and compare them to a baseline system using flashing
colored lights through a user study. Our work shows evidence that motion can be
used as a successful communication vector which is accurate, easy to learn, and
quick enough to be used, all without requiring any additional hardware to be
added to our platform. We thus contribute to "closing the loop" for human-robot
interaction underwater by proposing and testing this system, suggesting a
library of possible body language gestures for underwater robots, and offering
insight on the design of nonverbal robot-to-human communication methods.
