"Perspectives", a monthly column authored by
Todd Grimm for "Time-Compression Technologies."

This column was published in the
May 2005 issue. For more great articles,
visit the "Time-Compression Technologies'"
Web site at www.timecompress.com.

Virtual Versus Physical: Will Computer-Generated Virtual Prototypes Obsolete Rapid Prototyping?

by todd grimm

It is alluring to envision a design process where there are no physical models or prototypes. It is appealing to imagine product development without the delays and expense needed for the development of physical prototypes. And with advances in compute power, software applications and imaging systems, it is increasingly feasible to use virtual prototypes in lieu of physical, rapid prototypes.

But is this a practical reality or far-fetched fantasy? Will computer generated virtual prototypes replace and obsolete rapid prototyping?

The application of virtual prototyping in the product development process is not fantasy. It is used today, and with further developments, the number and breadth of applications will increase. However, proclamations that virtual will replace physical prototyping are pure fantasy, at least in our lifetimes.

Virtual Prototyping

Visualization, simulation and analysis are the hallmarks of virtual prototyping. Through digital representations, virtual prototyping provides a predictive tool for parts, sub-assemblies and products that have yet to take form in the real world. At one extreme, virtual prototyping is conducted in a virtual reality. With a CAVE* or power-wall*, design teams are fully immersed in a digital world that includes sensory feedback with haptic devices. At the other extreme, it may be as basic as a 3D, stereographic projection from a desktop computer screen. Between these two extremes lies a whole host of CAE tools that perform complex calculations and present the results through vivid displays of 3D digital data.

While few have access to immersive environments, there are many users of CAE applications, and there are a growing number of users of stereoscopic display devices. So, virtual prototyping has been proven to be practical and viable. Virtual prototyping is a reality.

However, just because virtual prototyping is possible does not mean that it will replace physical prototyping. Such a belief is based on the assumption that physical and virtual prototypes are mutually exclusive. And nothing could be further from the truth.

The Right Tool

Physical and virtual prototypes are not competitive technologies. They are complementary. The strengths and advantage of one technology will address the weaknesses and limitations of the other. In the future, industry leaders will have both technologies and the ability to select the best for the task at hand.

Imagine a design review meeting attended by engineers, marketing managers and executive management. If this meeting were to take place in a corporate conference room, which prototyping method would be preferred? Which would be most efficient? For most, presenting a physical prototype is both the preferred and most efficient method. Now, if this meeting were conducted in four cities around the globe, the virtual prototype may be the best choice.

Virtual prototyping applications will be those where rapid prototyping is impractical, impossible or inefficient. Applications may include prototyping of early design concepts and extremely complex, large products. For early concept models, where changes are fast and frequent, the virtual world may be the most practical and efficient. When reviewing and refining an aircraft design, physical prototypes of all components would be prohibitive in both cost and time. In such a case, virtual prototyping would be an ideal solution. However, for a form and fit evaluation of a reasonably sized part or assembly, rapid prototyping is will continue to be the best practice.

Another application where the virtual prototype will be ideal is in the area of simulation and analysis. Since rapid prototypes cannot deliver an exact match to the mechanical, thermal and electrical properties of a manufactured item, advanced CAE tools will fill the void between rapid prototype and prototype tooling. With greater speed, less cost and more accurate testing results, the virtual prototype is ideal for functional analysis. It is also ideal when the analysis is performed on something that cannot be witnessed in a rapid prototype, such as fluid flow.

Rapid prototypes will be the preferred solution when evaluating subtle, intangible aspects such as ergonomics. Without vast improvement in haptic devices, the virtual prototype will be a poor predictor of the fit of a pistol grip or the balance of a handheld power tool. Consumers often judge the quality of a product by its heft, the sound of a door closing or the texture of its finish. These are things that virtual prototypes do not convey.

Virtual Obstacles are Real

When building the virtual world, an incorrect assumption or an improper input value will produce a very real, virtual prototype that is inaccurate. The definition of these variables requires significant knowledge and experience. It also demands a significant amount of time. In many cases, it will be more efficient, productive and cost effective to let a rapid prototyping machine produce a physical prototype while the product design team tackles other action items.

Perhaps the greatest barrier to virtual prototyping overtaking rapid prototyping has nothing to do with technology. As history shows, the biggest barrier to new technology adoption lies within each of us.

Although those that do not use rapid prototyping may cite accuracy, material properties or surface finish as the obstacles to its use, for many the real reason is a resistance to change. The number of users of rapid prototyping would be much larger if change was not an issue. It is easier and safer to stay status quo. Changing technologies or processes requires efforts, opens the door to risk and moves us from our comfort zones.

Change will be a fundamental barrier to the adoption of virtual prototyping. Shifting to this technology takes effort and creates a risk potential. However, it also requires change at a fundamental level. Virtual prototyping asks that the user change the way that he communicates and the way that he receives communications. The virtual world is not real. So, the five senses either are stimulated to create the illusion of reality or are completely ignored. Seeking concrete answers, hard facts and an ability to test the real thing, many people will resist making a decision based on virtual information.

Knowing that the input is not real and understanding the limits of the virtual environment, product development professionals are unlikely to blindly trust the data that a virtual prototype provides.

Are all of the constraints and inputs correct? Is the visual simulation accurate? These are two of the many questions that will loom in the mind of the engineer or designer. Presently, there is no way that the virtual prototype can address these nagging concerns. As a result, the product design team will seek to confirm the virtual data with a physical prototype.

In the early days of rapid prototyping, there were predictions that it would replace NC/CNC machining. Fifteen years later, these predictions have proved false. The same will be true with similar predictions for the future of virtual prototyping.

Virtual prototyping will not replace rapid prototyping, but it will affect it. If virtual prototyping becomes widely used, it may significantly reduce the number of rapid prototypes that are made. In this scenario, a single rapid prototype would be used to verify the results of numerous virtual iterations. But this is not a foregone conclusion. There is the possibility that virtual prototyping increases the number of rapid prototypes.

Which of these realities will come true? Only time will tell.

* CAVE (Cave Automatic Virtual Environment) has four, five or six surfaces on which the digital image is projected. This surrounds the viewer with the virtual environment. Power-walls have one ore more rear-projection screens.


For more information, please contact Todd Grimm, Grimm and Associates, Inc. (Edgewood, KY) at (859) 331-5340 or email at tgrimm@tagrimm.com, or email at tgrimm@tagrimm.com.


Contact information:
printer friendly version Todd Grimm
T. A. Grimm & Associates, Inc.
3028 Beth Court, Edgewood, Kentucky 41017
Phone: (859) 331-5340      Fax: (859) 514-9721
tgrimm@tagrimm.com      www.tagrimm.com


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