Formation control of leader following unmanned ground vehicles using nonlinear model predictive control

In this paper, we present various formation keeping ability of multiple unmanned ground vehicles (UGV) using nonlinear model predictive control based method. The high-level formation control problems of multiple UGVs such as smooth path planning and collision avoidance between UGVs are solved using distributed nonlinear model predictive control method which sequentially solves the optimization problem on-line while sharing the predicted state of each UGV. The formation is guided by the leader UGV, which is controlled by the remote operator, while the rest of the UGVs are following the set points apart from the leader UGV by a specific distance. The optimal control input of each UGV is obtained by solving a discrete nonlinear kinematic model of an UGV sequentially using a gradient descent-based method. The formation keeping performance and the collision avoidance ability are verified through the realistic simulation in which the leader UGV is controlled by the operator's inputs and the following UGVs switch formations according to the operator commands.