Formation Control of Multiple Mobile Robots Based on Orientation Bias

The state coordination between robots in a multi-robot system is a crucial problem. In order to have a proper relative position and orientation of robots in a moving multi-robot formation, a coordination method is presented by using discrete orientation bias control. A moving structure graph for the formation is pre-specified. Based on the graph, a model of the formation is defined by two new kinds of artificial potential functions acting on each robot. The adjacent pair-wise robots in the formation are described in the cooperative leader-following framework without orientation constraints. The proposed control makes the global potential function maximum when the orientation bias between robots is zero. Therefore, the formation will follow its graph. In this case, the stability of the formation is proofed in the sense of Lyapunov. A simulation result of a marching square array with 9 robots is illustrated to validate the control with orientation bias.