arXiv:2611.07383v1 Announce Type: new Abstract: In this paper, we study the optimal consensus problem for multiagent systems with unknown dynamics. We propose a robust model predictive control (MPC) framework that jointly optimizes the control input and consensus sequences while enforcing state and input constraints. Within this framework, noisy offline data are used to construct nominal prediction models and quantify the associated uncertainty, which is explicitly incorporated into the robust MPC design. To solve the resulting optimization problem at each MPC update with reduced inter-agent communication, we develop a distributed gradient-projection alternating direction method of multipliers (ADMM) algorithm with an event-triggered information exchange mechanism and establish its convergence to the optimal solution. Furthermore, sufficient conditions are established to guarantee robust constraint satisfaction and practical consensus of the closed-loop multiagent system. Numerical simulations demonstrate the effectiveness of the proposed framework.