It's expensive to fly a 747, especially if you're training the pilot and not moving passengers. That's why airline pilots sharpen their skills in a flight simulator, where they don't burn any jet fuel.

Complex materials handling systems are also expensive propositions. No one wants to go through the expense of implementing a new solution, only to find that the automated storage systems, conveyors, guided vehicles or controls can't get the job done.

That's where simulation software comes into play. Think of these packages as a flight simulator for the warehouse or factory. Not only do they test new designs in a virtual world, but simulation software also produces an animated representation of a system in action. It actually shows the storage/retrieval machines, guided vehicles, and conveyors moving loads.

'Simulation software is an engineering tool,' says Matthew Rohrer, director of simulation products and services, Brooks Automation (801-736-3201). 'It's software that helps you build and prove models of your system.'

In fact, there are two types of software that fall under the simulation wing today.

First are simulation systems that model the operation whether it's a new system, an upgrade or even an entire supply chain. That model takes into account how the equipment works together as well as the inherent variability of these operations.

Next are emulation systems used to test programmable logic controllers (PLCs) and other control systems that direct materials handling operations.

Both identify bottlenecks and fine tune the system before going live.

'Simulation software allows you to electronically mirror your processes, including all the variability you might have in a materials handling situation,' says Peter Tiernan, director of marketing, Lanner Group, Inc. (713-532-8008).

It's that variability that can make all the difference when going from a static design to an operating system. Generally recognized design principles, sometimes referred to as industry standards, for materials handling systems are quite static. Simulation, on the other hand, provides a dynamic view of the system, including the variability of the manufacturing and distribution world.

What's more, industry standards can't replicate what happens when solutions such as an automatic guided vehicle system (AGVS) or automated storage and retrieval system (AS/RS) integrate with other materials handling equipment.

'Industry standards give you a starting point to figure out how many cranes you need in an AS/RS,' says Len Copus, simulation manager, Siemens Dematic (877-725-7500). 'But once you integrate those systems with an input conveyor, a forklift, or an AGV, there are handshake and timing issues that standards don't account for. Simulation is most powerful in helping you understand what happens.'

While simulation is a modeling and engineering tool, emulation is a testing tool that tests in a lab the control systems that will direct a materials handling system. Programmers can move individual as well as multiple loads through the system under the PLC control, for instance, and test all possible routings.

'Instead of going onsite and hooking up the PLC to the system, you can hook the control system up to a computer and test the code,' says Debbie Kotlarek, director of simulation and consulting, HK Systems (800-457-9783). 'That allows us to see if there are problems before going live.'

The number one reason companies simulate their systems is to prove an engineering design before going live. In fact, many customers insist on a simulation of the system before they will sign off on a project as insurance against failure.

'With a manual system, you can always add more people to increase the throughput,' says Florian Kompel, systems engineer, Swisslog Logistics(800-525-1841). 'But you can't just add another crane to an automated solution if it won't handle the peaks. Simulation gives customers the confidence that the solution you provide them is going to work.'

But that's not the only reason to simulate. It also reduces the design and implementation time. 'We recently simulated an AS/RS system with two load handlers that could each handle two cases,' says David Clary, systems engineer, Cleco Systems, Inc., an FKI Logistex company (770-795-9077). 'There were so many iterations of putaways and retrievals that you could never do that on paper. The time you spend on programming versus what you can get out of the system is pretty impressive.'

Finally, simulation allows you to look beyond the four walls of the facility. 'If you look out today, the manufacturing floor or the distribution center has to be connected to the rest of the supply chain,' says Vivek Bapat, director of marketing for simulation solutions, Rockwell Automation, (412-741-3727). 'Simulation software provides the tools to model the activity of an entire supply chain.'

That allows a user to not only decide how many cranes are needed-or not needed-in an AS/RS system, but where warehouses and distribution centers should be located.

'We recently built a model of Unilever's supply chain distribution network,' says Tiernan of the Lanner Group. 'To the user at Unilever, it looks like an Excel spreadsheet that queries them for information. But their entire network is operating in the background.'

While both simulation and emulation can go a long way toward proving a materials handling design and control system, there are limitations to the programs.

To start, simulation software can't create a materials handling design. 'You have to have a concept,' says Kotlarek of HK Systems. 'Simulation will evaluate those concepts.'

Nor can simulation find the optimal solution, only the best of tested solutions

What's more, as with all software, simulation is only as good as the data put into the system. Bad data produces flawed results.

Finally, to get the most out of simulation, the project objectives should be clearly defined. 'Just wanting to optimize your facility is not specific or clear enough to justify using simulation,' says Rohrer of Brooks Automation. 'But if you want to get 20% more throughput in your facility, simulation can tell you how close you can get to that goal.'

The biggest decision may not be to use simulation, but whether to do it in-house or outsource it to an expert with simulation experience.

Historically, most companies have turned to consultants or systems integrators to provide the service for them as part of the design process.

'The biggest advantage an integrator brings to the table is knowledge of the controls of a system,' says Kotlarek of HK Systems. 'A user may know that the conveyor is moving at 60 feet per minute. But an integrator understands the mechanical and electrical controls and can translate that into the software.'

But the real benefit of simulation comes from having more model users with the tools in their hands. That may be a warehouse or plant manager who wants to simulate changes to the facility and their impact on operations or the number of personnel required. It may also include a vice president of logistics who wants to model changes to the overall supply chain.

In recent years, the price of simulation software packages has come down dramatically, making the packages more attractive to doing simulation in-house. But there's more to the decision than just the cost of the software itself.

A successful simulation strategy needs someone who can be trained to operate the software. Preferably, that's someone who can be dedicated to the position, and who understands materials handling as well as distribution and manufacturing systems.

Since that person should also be dedicated to simulation, Rohrer of Brooks Automation says most companies should have two medium-to-large projects a year, like a facility redesign, in order to justify doing simulation in-house.

'If I was sitting out there with one project that needs to be done, I would turn to a consultant with simulation experience,' agrees Bapat of Rockwell Automation. 'If my company has made a commitment to using simulation going forward, then I would create a team to do these things internally.'

In any case, simulation and emulation are two software packages that can save any warehouse or shop floor from a flawed materials handling system.

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