Formation control for mobile multiple robots based on hierarchical virtual structures

The formation control problem of mobile multiple robots is investigated. A formation control scheme based on a hierarchical virtual structure is proposed. The mobile robots are divided into some clusters according to their distributions in space and then the motion trajectory of every cluster (virtual structure) is defined, so the motion of virtual structure is transformed to desired trajectory of every robot. Furthermore, a finite-time tracking control algorithm with variable structure is proposed. And two designed control laws based on state feedback are constructed to stabilize steering angle error and positions error in finite time, respectively. Involving in results about finite-time stability, we prove that the desired trajectory is attained fully in finite time with the two control laws. Finally numerical simulations considering line-shape and circle-shape are respectively carried out and show the effectiveness of the proposed control scheme.