I think we can all agree that “control systems” such as Warehouse Management Systems (WMS) and Warehouse Control Systems (WCS) are at the heart of every Materials Handling Automation (MHA) system. It is the control software that determines how efficiently pick modules are replenished, orders are picked, and containers are routed to packing, sorting, and shipping areas. Compared to the cost of a new picking and sorting conveyor system, changes to the software of an existing system are relative cheap.

Robert J. Graves, Sr. Professor of Emerging Technologies at Dartmouth College (Robert.graves@dartmouth.edu), said in a report on the subject “If you can get 30% to 35% improvement with software changes, you’re addressing the most cost-effective way to improve throughput”. Graves, working with one of his Dartmouth PhD students a few years ago, applied a relative new concept in controls software known as Holonic Controls Architecture to an MHA system.

Graves understood that future MHA systems need to cope with frequent changes and disturbances. As such, their control systems will require constant adaptation and high flexibility. Holonic control software is a highly distributed control paradigm that promises to handle these problems successfully. It is based on the concept of autonomous co-operating agents, called ‘holons’.

The purpose of Graves’s exercise was to see how this new software concept can lead to improvements in throughput, uptime and accuracy over traditional control architecture. Working with a real-world system description, control code, system simulator and test order data provided by Vanderlande Industries, Graves was able to complete head-to-head testing with a rebuilt system against the original control code.

The result: “We were able to demonstrate throughput improvements of up to 35% with a revised control system verses the original control system”, Graves said. He believes that his test project is an example of how the MHA industry and the academic world can successfully work together to innovate.

Final Thoughts

What this really points out is that companies that are not keeping their control system up-to-date, especially with regard to advanced software concepts, will eventually become non-competitive. Worse yet, their systems will eventually become antiquated. Once that happens, service technicians will not be able to put “Humpty-Dumpty” back together again.

While frequently upgrading your current control systems is relatively cheap, non-disruptive, and proven to be productive; replacing those systems is not cheap, will disrupt operations, and most likely increase customer dissatisfaction during the process.

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