“…Velocity planners fix the paths that will be followed by each robot, then find a velocity schedule along those paths that avoids collisions [5,29,30,31,32,33,34]. Priority planners assign a priority to each robot, then plan for individual robots in decreasing order of priority, treating higher priority robots as moving obstacles [4,35,36,37,38,39]. The choice of priority ordering is critical, leading to a number of heuristics for choosing priority orders that are likely to lead to a solution [38,40,41].…”