  We study optimal Multi-robot Path Planning (MPP) on graphs, in order to
improve the efficiency of multi-robot system (MRS) in the warehouse-like
environment. We propose a novel algorithm, OMRPP (One-way Multi-robot Path
Planning) based on Integer programming (IP) method. We focus on reducing the
cost caused by a set of robots moving from their initial configuration to goal
configuration in the warehouse-like environment. The novelty of this work
includes: (1) proposing a topological map extraction based on the property of
warehouse-like environment to reduce the scale of constructed IP model; (2)
proposing one-way passage constraint to prevent the robots from having
unsolvable collisions in the passage. (3) developing a heuristic architecture
that IP model can always have feasible initial solution to ensure its
solvability. Numerous simulations demonstrate the efficiency and performance of
the proposed algorithm.
