This paper seeks to combine differential game theory with the actor-critic-identifier architecture to determine forward-in-time, approximate optimal controllers for formation tracking in multi-agent systems, where the agents have uncertain heterogeneous nonlinear dynamics. A continuous control strategy is proposed, using communication feedback from extended neighbors on a communication topology that has a spanning tree. A model-based reinforcement learning technique is developed to cooperatively control a group of agents to track a trajectory in a desired formation. Simulation results are presented to demonstrate the performance of the developed technique.Rushikesh Kamalapurkar, is with the School system for each agent is a complex nonautonomous dynamical system. Nonautonomous systems, in general, have nonstationary value functions. Since non-stationary functions are difficult to approximate using parameterized function approximation schemes such as neural networks (NNs), designing optimal policies for nonautonomous systems is challenging.Since the external influence from neighbors renders the dynamics of each agent nonautonomous, optimization in a network of agents presents challenges similar to optimal tracking problems. Using insights gained from the authors' previous work on optimal tracking problems [39], this paper develops a model-based RL technique to generate feedback-Nash equilibrium policies online, for agents in a network with cooperative or competitive objectives. In particular, the network of agents is separated into autonomous subgraphs, and the differential game is solved separately on each subgraph.The primary contribution of this paper is the formulation and online approximate feedback-Nash equilibrium solution of an optimal network formation tracking problem. A relative control error minimization technique is introduced to facilitate the formulation of a feasible infinite-horizon total-cost differential graphical game. Dynamic programming-based feedback-Nash equilibrium solution of the differential graphical game is facilitated via the development of a set of coupled Hamilton-Jacobi (HJ) equations. The developed approximate feedback-Nash equilibrium solution is analyzed using a Lyapunov-based stability analysis to demonstrate ultimately bounded formation tracking in the presence of uncertainties.Patrick Walters received the Ph.D. degree in mechanical engineering from the University of Florida, Gainesville, FL, USA, in 2015. His research interests include reinforcement learning-based feedback control, approximate dynamic programming, and robust control of uncertain nonlinear systems with a focus on the application of underwater vehicles.Prof. Warren E.