The term engineering has a positive meaning, typically describing
the act of creating something beneficial to industry or society. But
add the word reverse, and it becomes something quite different. Reverse
engineering is often associated with the sometimes-illegal act of
copying an original design for competitive purposes, but this
perception is quickly changing.
A
new, more-positive definition of reverse engineering is unfolding. For
many modern manufacturers, the term now describes the process of
capturing a part with a 3-D scanner, reconstructing the measurement
data (point clouds) into highly accurate polygon or NURBS surfaces, and
using the resulting digital model for applications such as product
design, tool and mold design and verification, customized
manufacturing, recreating legacy parts, engineering analysis, and
computer-aided inspection.
Reverse engineering is fundamentally different from traditional
CAD/CAM. With its roots in drawing, CAD/CAM software is limited to
prescriptive modeling methods. In other words, pre-defined geometry
must be prescribed by an expert to a software tool for the purpose of
modeling. CAD/CAM starts in the virtual world with a goal to produce
better products in the real world.
With its roots in imaging, reverse engineering offers descriptive
modeling methods. The software extracts geometry and topology
information from measurement data and describes it to a user. Reverse
engineering starts in the real world with a goal to produce
high-quality digital models in the virtual world that can be used by
CAD/CAM/CAE applications.
Combining the two methods creates a complete closed-loop solution-from real to virtual to real.
Dual representations of data and physical phenomena have been behind
many scientific breakthroughs. Take physics, for example. Maxwell,
Hertz and others made great progress in understanding light as part of
an electromagnetic spectrum. But it wasn't until discrete-particle
models (photons) were set side-by-side with their continuous brethren
that physics made a quantum leap. Today, models of light-as-a-wave and
light-as-a-particle work side-by-side.
Engineers routinely examine mechanical and electrical events
(signals, noise, vibration) in both the time and frequency domains.
Problems that are extremely difficult to solve in one domain are often
simple to solve in the other. The invention of the Fourier transform,
which allows any time domain measurement to be examined in the
frequency domain, has driven spectacular progress in many fields.
The two digital domains in the manufacturing world could be thought
of as the shape domain (traditional CAD) and the point domain (reverse
engineering). Traditional CAD is based on mathematics that define
continuous curves and surfaces. It's great at modeling new products,
particularly those with simpler boundaries. But, it's cumbersome for
capturing the complexity of the existing world.
The natural complement to continuous mathematics is discrete
mathematics-handling geometry as sets of discrete points. This is what
reverse engineering does. Discrete modeling bridges the gap between the
point domain of measurement and the shape domain of design. When
combined with the continuous mathematics of CAD/CAM, discrete modeling
represents the next quantum leap in product design and manufacturing.
Reverse engineering aligns the physical and digital worlds, ensuring
that the design model is an accurate representation of the as-built
product. This alignment is often missing in CAD/CAM, where changes
required to adapt a design to manufacturing create differences between
the CAD model and the physical product. Accurate alignment between the
digital representation and as-built product provides major benefits,
including the following:
* Faster development cycles due to fewer design iterations
* More accurate computer-aided engineering analysis
* Better fit and finish of final products
* Less manufacturing waste
* The ability to customize products in mass quantities
* Faster and more accurate quality inspections
Here are just a few examples of how reverse engineering is making its presence felt in today's manufacturing environment:
* In the automotive world, Japanese manufacturers are using reverse
engineering to shorten the process of developing a full-scale car
design from three months to three days. Racing teams are using new
digital processes to capture, recreate, and test engine and body parts
that are critical to a car's on-track performance.
* Aerospace companies employ reverse engineering to create digital
inventories of legacy parts, and to cut first-article inspection of
turbines and other parts by 40% or more.
* In the medical market, reverse engineering processes are the
foundation for mass manufacturing of hearing instruments, orthodontic
devices, and dental appliances that are custom-made to fit an
individual perfectly. These new products look better, feel comfortable,
and are more effective in treating medical conditions.
And there are many more uses. My company, Raindrop Geomagic, has
helped designers and engineers capture scan data from physical parts
and create highly accurate digital models for applications such as
digital dentistry, the historic preservation of the Statue of Liberty,
the redesign of a retro Harley-Davidson gas tank, and quality
inspection to ensure that circuit breakers will last 400 years. The
possibilities are virtually endless.
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