Mechatronics Sizzles with Modeling, Simulation

Thanks to the Power of Computers and the Fidelity of Simulations, an Entire Mechatronics Solution Sometimes Can be Tried Out and Verified Before Anything is Actually Built

By Hank Hogan

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The same weekend the 2013 Super Bowl went dark due to a power outage, Russ Klisch, president of Lakefront Brewery, was hoping to avoid a somewhat similar fate. The Milwaukee-based craft brewer was installing a new filler, the machine that puts a beverage in a bottle.

Unlike the big game, Lakefront's switchover went off without a shutdown. This was, in part, due to the successful application of mechanical, electrical, control and software, or mechatronics, expertise. The new machine has proven effective, Klisch reports.

"Our uptime went from 80-90% to 99% runtime," he says. "We were running around 125 bottles a minute.
Now we're up to about 190 bottles a minute."

These results and how they were achieved illustrate some important points about mechatronics. Thanks to the greater integration of functions and more software, mechatronic systems are growing more complex. As a result, modeling is increasingly important. This greater upfront work can pay off in more capable systems and/or the completion of projects in less total time. But there are downsides to this approach, one being a need for greater modeling and software expertise. Such model-based design methods also take longer to produce hardware, and this lack of physical proof of progress can be seen as a disadvantage.

Better Bottling

In the case of beer bottling, the filling machine is important to more than the quantity of product produced. It has to be precise, ±1.5 ml. For a 12-oz bottle that translates to 0.4% accuracy. What's more, filling has to be done without dissolving oxygen in the beer, as too much of the gas makes for a flat and stale taste. The industry specification is that dissolved oxygen be below 100 parts per billion. There's also the need to ensure the safety of the beverage by preventing bacterial growth.

The new filler easily betters the oxygen content mark, according to Klisch. It's also more hygienic and accurate than the old machine.

Other improvements include a 50% or better reduction in the time it takes to change over from one product to another, which is an important benefit in the craft beer market. The new filler is more energy-efficient and more tightly integrated with other machines in the plant. Thus, when there is a problem, conveyors and other supporting equipment stop automatically.

The filler is a product of Waukesha, Wisconsin-based KHS USA, a machine builder with long experience in the beverage industry. Director of engineering Jeff Gilberg says the filler process involves pulling a vacuum on a bottle, purging it with carbon dioxide, filling it with a precise amount of the beverage, and finishing by injecting water. There are slight variations in the process between different types of beer.

Also Read: Mechatronics: Think Inside the Box

The new filler was smaller than others the company had built before, and it faced cost constraints while still needing to ensure product quality. That, in turn, demanded certain mechatronic performance specifications. "We had to make sure that the fit for the servo drives was proper, so we could have the right torque requirements for this small application and be cost-effective in doing it," Gilberg says.

Accomplishing this involved some simulation, using software from SolidWorks and PTC. KHS also used Rockwell Automation's motion analyzing and control logic simulation software, along with one of its programmable automaton controllers tightly synchronized with the same brand of servo drives and motors via an EtherNet/IP network.

The hardware provided motion control without a dedicated network, while the combination of simulation software allowed prediction of torque load to within 10%. Getting the simulation right was important, as having too small motors would keep the machine from working properly, while too large motors would be expensive and inefficient.

There are three servomotors on the machine that handle the motion. These motors are independent mechanically, but are synchronized electronically, so they appear to act as one, according to Gilberg. Valves and other functions on the machine are controlled using essentially the same logic and approach that bigger filling machines follow.

Since the successful rollout of the smaller filler, KHS has sold additional machines to several of the nearly 3,000 craft brewers in the U.S. One result has been dramatic increases in efficiency, with some end users getting as much product out in one shift as they previously did in two.

Growing Complexity

As this project shows, the software side of mechatronics is becoming more complex, something that Tony Lennon, industrial automation specialist with MathWorks, points out. The mathematical computing software company's platform for modeling and simulating dynamic systems is Simulink, which can help automate the chore of creating software. It does so by generating code from a model-based design.

This automated approach saves time and prevents errors, Lennon says. "In regard to code generation, Simulink can generate ANSI/ISO C code for microprocessors, IEC 61131 structured text for PLC systems and HDL for FPGAs."

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