Simulating Passivity for Robotic Walkers via Authority-Sharing

We consider a robotic walking assistant used to guide senior users across a crowded space. The problem we address is how to guide the user using motorized back wheels. Our strategy aims to simulate a passive behavior in which the forward velocity is the one imposed by the user, who receives the impression of controlling the motion. The result is obtained leaving the user in control (without any actuation) when she/he follows straight lines, while the motors kick in when the user has to make a turn. We offer extensive theoretical proof of the validity of our strategy. The technique has been validated via extensive experimentation with a large group of older adults.