Reader Question

Your article on task interleaving in a distribution center was excellent, but I have a follow-up question.

Which is the mathematic algorithm that a WMS uses to do this optimization?

Distribution Center Manager
Industrial Distribution Company

Category: Distribution

Expert Panelist Response: From Tom Kozenski, VP of Product Strategy, RedPrairie

The algorithm is based on this logic sequence:

  • Firstly, the WMS sorts the list of potential tasks in the work queue based on the permissions of the user /vehicle combination (example – Case Handler on a Cherry-Picker)
  • Then sort that list by priority, listing the most important tasks first
  • Lastly, the algorithm will select the closest task with that highest priority. This selection is done by calculating the distance of each “task candidate” by using the 3D Warehouse Map. It calculates distances for each of the highest priority task. It optimally uses access points between aisles, so that it can accurately determine if a location in the next aisle is actually closer than a location in the same aisle where the operator is currently stationed. This eliminates unnecessary travel time.

Key point – All of this logic has to occur with sub-second response time, as the operators are on either RF or Voice technology and do not want to stand waiting for long periods of time waiting for their next assignment.   

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