  Collective dynamics can be observed among many animal species, and have given
rise in the last decades to an active and interdisciplinary field of study.
Such behaviors are often modeled by active matter, in which each individual is
self-driven and tends to update its velocity depending on the one of its
neighbors.
  In a classical model introduced by Vicsek and al., as well as in numerous
related active matter models, a phase transition between chaotic behavior at
high temperature and global order at low temperature can be observed. Even
though ample evidence of these phase transitions has been obtained for
collective dynamics, from a mathematical standpoint, such active systems are
not fully understood yet. Significant progress has been achieved in the recent
years under an assumption of mean-field interactions, however to this day, few
rigorous results have been obtained for models involving purely local
interactions.
  In this paper, as a first step towards the mathematical understanding of
active microscopic dynamics, we describe a lattice active particle system, in
which particles interact locally to align their velocities. We obtain
rigorously, using the formalism developed for hydrodynamic limits of lattice
gases, the scaling limit of this out-of-equilibrium system.
  This article builds on the multi-type exclusion model introduced by Quastel
by detailing his proof and incorporating several generalizations, adding
significant technical and phenomenological difficulties.
