I. Introduction
A special class of multi-robot formation control is the motion control of a group of robots led by a human leader. For example, the formation control of robotic wheelchairs which are accompanied by human caregivers [1], or the multi-robot formation control in shared rescue missions [2]. A basic problem when considering multi-robot scenarios is how to maintain a specific shape while moving around. This problem has been addressed in the literature by model based (e.g. [3]–[5]), potential-field based [6], graph based [7], or combined approaches [8]. A lot of these approaches yield non-linear control laws which are difficult to implement on low-cost hardware.