Collision-free Coordination of a Group of Unicycle Mobile Robots

We propose a method for collision-free coordination of a group of unicycle mobile robots. A supervisory system assigns to each robot its reference path, together with the desired velocity profile as a function of the position along the path. While the collisions of the robots are not acceptable, the reference paths and velocity profiles do not necessarily prevent the collisions. Feedback controllers of individual robots coordinate their motions along the assigned paths such as to ensure collision-free movements. These controllers realize globally asymptotic stable tracking of the reference trajectories under constraints on the actuator inputs. The controllers proposed here offer several advantages with respect to those in the literature, such as better suppression of tracking errors due to more freedom in controller tuning and relaxed constraints on the reference velocities. The coordination method and the feedback control design have been successfully validated in experiments. These ca be used for the realization of autonomous transportation tasks in warehouses, harbors, factories, etc.