March 13, 1998

Have you considered using real models?

No, I'm not talking about the glamorous models who grace the covers of fashion magazines and walk down fashion-show runways or about the software-based models that electronics engineers routinely use to simulate circuitry, waveforms, ICs, and system performance with nanosecond precision.

Most design engineers don't design just an IC or a pc board, and they cannot ship a simulation. They actually have to produce a complete product, such as a cellular phone, an em-bedded controller, a power supply, or a data-acquisition system. As these products get smaller, it becomes challenging to fit all their parts into an enclosure. Parts locations, clearances, thermal issues, appearances, human factors, and assembly sequences are critical to the design and to circuit performance.

But don't despair. Only a few years ago, the easiest way for a designer to do a 3-D physical simulation was to build a mockup from cardboard, plastic, wood, or even clay. Now, however, solid-modeling software lets you build realistic models of your major system elements, such as the power supply, pc board, keyboard, and display, and manipulate them on-screen. These models need not be photorealistic to be effective, either. Even a basic 3-D silhouette (named after the man who popularized them, Étienne de Silhouette (1709 to 1767), Louis XV's minister of finance) can provide much of the information and reality you need.

Such modeling lets you see the impact of changes, such as trimming a pc board by a few millimeters or shifting a taller component on a pc board so that the component is not underneath a thicker component on the front panel. You can also determine the overall weight and center-of-gravity location, especially important for handheld products.

You can go even further with these modeling packages. Most of them link to "rapid-prototyping" systems, which create a 3-D part before your eyes. They accomplish this task by driving a laser beam that dances along the top surface of a photosensitive polymer, which hardens where the beam hits the liquid. Within 5 to 20 minutes, you have a hard-plastic part of reasonably high dimensional accuracy that you can use for further study or for testing with potential users.

Don't stop with just mechanical modeling. Other software packages let you create a virtual-reality picture of your product's front panel, keyboard, and display on a PC screen and then respond to user inputs with appropriate display messages, as if the user had the final product in hand. With these packages, you can quickly and conveniently test possible user sequences and messages and determine that what seems obvious to you, as a product designer, is perhaps confusing and frustrating to the people who are supposed to actually buy your design.

Reference

1. Teague, Paul, "Why engineers seek solid ground," Design News, Jan 19, 1998, pg 64. id-modeling software lets you build realistic models of your major system elements, such as the power supply, pc board, keyboard, and display, and

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