Approximation of an optimal control problem on a network with a perturbed problem in the whole space
Mohamed Camar-Eddine, Mériadec Chuberre, Mounir Haddou, Olivier Ley
TL;DR
This work analyzes a singular perturbation of a classical infinite-horizon optimal control problem in $\mathbb{R}^2$ aimed at concentrating trajectories on a network $\Gamma$ via a term $\frac{1}{\varepsilon}\nabla d$. It develops a framework linking the $\varepsilon\to 0$ limit to optimal control problems on networks, proving subsequential convergence of trajectories to $\Gamma$ and, in the Eikonal case, convergence of the value function to the network value function $V_{\Gamma}$. Under controllability and cost-structure assumptions, the perturbed value functions $V^{\varepsilon}$ converge locally uniformly to $\overline{V}\circ\phi_d$, with $\overline{V}=V_{\Gamma}$ on $\Gamma$, thereby connecting full-space control with network formulations. The results offer a principled route for approximating network-based optimal control problems via classical singular perturbations, and they reveal subtle phenomena near the junction, including potential nonuniqueness and semigroup failures in the limit dynamics.
Abstract
A classical optimal control problem posed in the whole space R^2 is perturbed by a singular term of magnitude $ε$^{-1} aimed at driving the trajectories to a prescribed network $Γ$. We are interested in the link between the limit problem, as $ε$ $\rightarrow$ 0, and some optimal control problems on networks studied in the literature. We prove that the sequence of trajectories admits a subsequential limit evolving on $Γ$. Moreover, in the case of the Eikonal equation, we show that the sequence of value functions associated with the perturbed optimal control problems converges to a limit which, in particular, coincides with the value function of the expected optimal control problem set on the network $Γ$.
