  This paper describes a novel approach in human robot interaction driven by
ergonomics. With a clear focus on optimising ergonomics, the approach proposed
here continuously observes a human user's posture and by invoking appropriate
cooperative robot movements, the user's posture is, whenever required, brought
back to an ergonomic optimum. Effectively, the new protocol optimises the
human-robot relative position and orientation as a function of human
ergonomics. An RGB-D camera is used to calculate and monitor human joint angles
in real-time and to determine the current ergonomics state. A total of 6 main
causes of low ergonomic states are identified, leading to 6 universal robot
responses to allow the human to return to an optimal ergonomics state. The
algorithmic framework identifies these 6 causes and controls the cooperating
robot to always adapt the environment (e.g. change the pose of the workpiece)
in a way that is ergonomically most comfortable for the interacting user.
Hence, human-robot interaction is continuously re-evaluated optimizing
ergonomics states. The approach is validated through an experimental study,
based on established ergonomic methods and their adaptation for real-time
application. The study confirms improved ergonomics using the new approach.
