What has your WMS vendor done for you lately?

One of the challenges identified at last summer's workshops for the Material Handling and Logistics Roadmap was the use of optimization tools to improve warehouse operations. It was widely believed that the state of the art far exceeds the state of practice. That is, we know how to optimize certain aspects of warehouse operations, and yet very few firms are making use of the algorithms and tools that make it happen. How come?

Let's take order picker routing as an example. In many manual order picking environments, the WMS batches orders into a pick list for the worker. Deciding which orders should go into the batch is actually a difficult problem, but let's skip that for now. Once the batch is determined, the lines must be sequenced such that the picker travels as little as possible. That is, we wish to minimize the length of the picking tour, thereby maximizing the worker's productivity.

[Source: www.directindustry.com]

Sequencing pick locations to minimize the length of a tour is a form of the famous "traveling salesman problem" (TSP), which asks in what sequence a salesman should visit a collection of cities in order to minimize his travel time. The TSP has received more attention in the operations research community than perhaps any other problem, and we now have very efficient methods for solving very large instances. For order picker routing, that means optimal methods exist to solve almost any problem. And by "optimal" I don't mean "very good" or "excellent." I mean we can generate picking tours that are provably as short as possible, and we can do it very quickly.

Which brings me back to the WMS. How many WMS vendors actually optimize order picker routes? I don't know the answer to that question, but an anonymous vendor in a land far, far away once confessed with chagrin that they used the most naïve algorithm imaginable. When asked why, the engineer told me, "Customers haven't requested optimization." There you have it—a perfectly rational explanation! What this vendor was telling me was essentially, "We build into our product what our customers want, not what we think they might want."

And now the $64,000 question for WMS customers: Have you asked for optimal routing methods? Do you know they exist? Have you asked for optimal slotting methods, which also exist? Have you asked for details on the order batching algorithms under the hood?

If you are a WMS vendor that uses optimal routing algorithms for order picking, by all means write to let me know. I'll be glad to update this post. If you are a WMS user wishing your WMS was as good as it could be...

You do not have, because you do not ask.