  We formulate an optimization problem to control a large number of automated
guided vehicles in a plant without collision. The formulation consists of
binary variables. A quadratic cost function over these variables enables us to
utilize certain solvers on digital computers and recently developed
purpose-specific hardware such as D-Wave 2000Q and the Fujitsu digital
annealer. In the present study, we consider an actual plant in Japan, in which
vehicles run, and assess efficiency of our formulation for optimizing the
vehicles via several solvers. We confirm that our formulation can be a powerful
approach for performing smooth control while avoiding collisions between
vehicles, as compared to a conventional method. In addition, comparative
experiments performed using several solvers reveal that D-Wave 2000Q can be
useful as a rapid solver for generating a plan for controlling the vehicles in
a short time although it deals only with a small number of vehicles, while a
digital computer can rapidly solve the corresponding optimization problem even
with a large number of binary variables.
