How to Always Keep an Eye on the User with a Mobile Robot?

Using mobile robots in rehabilitation is an upcoming trend in the field of robotic healthcare. A possible application is robot assisted self-training after orthopedic knee or hip endoprosthesis surgery. In this scenario, it is particularly important to be able to continuously observe the patients movements in order to give timely feedback on the ongoing exercise. This paper presents a complementary approach separately taking care of two fundamental prerequisites of an application scenario where a user performs gait retraining in rehabilitation under supervision of a mobile robot: driving at a certain constant distance in front of the user and keeping the user at a suitable position in the sensor's field of view. We show the applicability of our approach under laboratory and real-world conditions.