Nonsingular formation control of cooperative mobile robots via feedback linearization

This paper addresses the control of a leader-follower formation where the leader robot has its own target and the follower robots are constrained by the specified formation tasks. The dynamics of the leader robot with nonholonomic constraint is explicitly integrated into the formation system to yield a centralized coordinating controller. As a result there is no need to assume the motion of the leader separatively when we develop cooperative formation controllers for coordinating the robots. The feedback linearization is used to deal with the nonlinear formation control of a team of autonomous mobile robots with nonholonomic constraints. Although the nonlinear formation system under consideration can be exactly linearized by taking advantage of dynamic feedback linearization, there exists structural singularity which may pose serious problems in practice. To solve this singular problem a new formation model for controlling the leader-follower formation in a cooperative manner is developed. This new formation model can be extended to studying other control and learning issues in multi-robot systems for both cooperation and noncooperation. The internal dynamics is derived and proven to be globally stable under the stable linear controller obtained via the partially linearized dynamics. To demonstrate the performance of the developed formation controller, simulation results are provided.