  Recently we developed partial-observation supervisor localization, a top-down
approach to distributed control of discrete-event systems (DES) under partial
observation. Its essence is the decomposition of the partial-observation
monolithic supervisor into partial-observation local controllers for individual
controllable events. In this paper we extend the partial-observation supervisor
localization to large-scale DES, for which the monolithic supervisor may be
incomputable. Specifically, we first employ an efficient heterarchical
supervisor synthesis procedure to compute a heterarchical array of
partial-observation decentralized supervisors and partial-observation
coordinators. Then we localize each of these supervisors/coordinators into
partial-observation local controllers. This procedure suggests a systematic
approach to the distributed control of large-scale DES under partial
observation. The results are illustrated by a system of automatic guided
vehicles (AGV) serving a manufacturing workcell.
