Leader-follower formation control for multiple mobile robots with velocity constraints *

This paper deals with leader-follower formation control of mobile robots, including a leader robot trajectory tracking strategy and a follower robot formation maintaining strategy. Robots' control inputs are limited to satisfy practical constraints that restrict the range of feasible leader paths and possible positions of the follower with respect to the leader. First, a backstepping control method is used to develop a trajectory tracking controller that enables the leader robot to track the desired formation trajectory quickly. Then, a Nonlinear Model Predictive Control (NMPC) technique is employed to transform the formation dynamics of the follower robots into a quadratic programming(QP) optimization problem with velocity constraints. In order to effectively tackle the optimization problem, a Primal-Dual Neural Network (PDNN) solver is implemented to obtain the optimal solution. Finally, numerical simulations are demonstrated to validate the effectiveness of the proposed formation control method.