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Small Tool, Big Potential

3D scanning tool becomes portable with Matrox 4Sight

There is no question that Henry Ford revolutionized the manufacturing industry; it was the Ford Motor Company, after all, that was first to build mass-produced cars on an assembly line. Almost one hundred years since the first Model T, modern auto makers still face many challenges in terms of design and production.

Perceptron (Plymouth, Michigan) understands the demands of today's auto industry. Founded in 1981, the company was a pioneer in the field of machine vision, and has since developed a number of technical innovations used by the world's largest auto makers. One example is ScanWorks®, a versatile 3D scanning tool launched in 2000. A mechanical arm equipped with a V4i Sensor having a custom laser, camera, and control electronics, along with an off-the-shelf industrial computer, ScanWorks® simplifies reverse engineering, point cloud-to-CAD comparison, 3D visualization and inspection applications.

"Human beings live in a physical world, a 3-dimensional world," says Rhex Edwards Director of Sales & Marketing, Technology Components Group. "But computers exist in two dimensions." Translating human vision into a computer's 2D system has sent engineers and programmers scratching their heads since the early days of computing; algorithms that generate 3D data use a lot of processing resources. Three-dimensional visualization has become much more attainable in the wake of powerful processor chipsets; today's technology allows computers to 'function' in 3D systems. "Furthermore, the ability to collect data and instantly share it with colleagues and suppliers around the world increases communication beyond anything imaginable just a few years ago," Edwards adds. Better communication translates into fewer questions when problem arise; everyone involved has the same information in the 3D image - information that can be shared by many disciplines of engineering as necessary.

All-in-one tool

"ScanWorks® is designed to be a complete subsystem," explains Mike Morris, Product Development Manager for ScanWorks®. "It includes all the hardware and software needed to collect data and prepare it for customer use."

Image 1

The Matrox 4Sight M controls the camera, and performs image
processing operations and mathematical transforms on
the ScanWorks® sensor.

Using triangulation, a Perceptron ScanWorks® sensor captures profiles generated by the intersection of a projected laser plane and the target topography. Controlled by a Matrox 4Sight-M industrial computer, the camera acquires the image of the beam's reflection. The Matrox 4Sight M then performs a number of image processing operations and mathematical transforms creating a raw data stream. This data stream, consisting of many thousands of individual points per second, is transferred, via a standard Ethernet cable to the user's PC / laptop for live display and further processing. A technician uses the mechanical arm which carries the ScanWorks sensor to acquire the profiles for each of the object's surfaces in the part's design coordinate frame. The ScanWorks software merges the data together (potentially several million points) to produce accurate digital 3D part topography.

ScanWorks® software further processes the data to a user's specifications, and the result is a point cloud that can be used for reverse engineering, prototyping, or inspection. Most of Perceptron's direct clients are manufacturers of automobiles or automobile components, so ScanWorks® is the tool of choice for myriad automotive assembly, design, and production applications. Indeed, one customer resolved a design flaw in an ornamental plastic part for a car's body panel. After scanning the part and comparing it to the original CAD drawing, the customer determined that the part had been manufactured correctly. Further investigation showed the parts were warm when placed in the shipping dunnage. "ScanWorks® helped the customer trace the problem to the shipping and handling procedures," recalls Edwards. "That avoided a potentially costly tooling rework problem." In a prototyping and design application, a design engineer molds a body panel with complex curves out of clay for a new model. "With the point cloud generated by ScanWorks®, the algorithms can resolve the equation for a curve in a fraction of the time it would take a developer," explains Morris.

Image 2

A part is scanned with the probe.

Image 3

Image 4

The 3D images of the scanned part.

With the exception of the Matrox 4Sight M, all of the ScanWorks® V4i Sensor's components are custom-built for Perceptron: the camera, lens, laser and electronic controls. The V4i sensor projects an optical beam accurate to 24 micrometers at 2 sigma. The camera captures the image data at a rate on the order of 456 000 points/second. Portability is key for ScanWorks®, and Morris says the compact Matrox 4Sight M platform fit Perceptron's performance requirements. ScanWorks® software was designed in-house as well. "Perceptron has been doing machine vision for 25 years, we just ported our algorithms to the Matrox [4Sight M] hardware platform," says Morris.

Making the connections

During ScanWorks'® infancy, the engineering team at Perceptron focused on the most important design objective: to create portable equipment that could be calibrated quickly with minimal additional tools; customers need to transport it to the job site with a minimum of delay. As a result, Edwards says the engineers faced many challenges in the integration domain. "We had to get the laser, camera, lens and mounts to work together to meet our performance goals." And meeting the accuracy specifications for the micrometer category was no small engineering challenge. Edwards says the engineers persevered, and developed not one, but a family of ScanWorks® products that address the varying situations Perceptron's customers encounter. "This resulted in more choices for our customers, fewer overall parts, and a more robust solution for everyone," he says.

Managing the image processing tasks also presented development challenges. Given the vast amount of data the sensor can generate, Morris correctly predicted the need to off-load the image processing tasks from the user's PC / laptop. "The volume of data we need to process can swamp any CPU," Morris notes. "During our development phases, we pushed the camera and laser to their limits, and we watched how many CPU cycles we were chewing up in our algorithms." ScanWorks®, then, uses a dedicated Matrox 4Sight M for as much of the image processing tasks as possible. To enhance the data throughput capability, Morris's team opted for a dedicated 10/100 Ethernet transfer protocol. They optimized the network parameters and thread priority model, so the results move swiftly to the user's laptop or desktop. Due to the large amount of data ScanWorks® provides the users must use high-end computers.

Today and tomorrow

ScanWorks® solutions provide portability, flexibility, and accuracy for almost any engineering activity where information about the form and size of an object are important. By collecting this data quickly at the source, it can be used to make informed decisions about the product, tooling, or processes that create the product. This translates into savings in time and money while reducing the overall risks associated with inadequate data or information. And it's a cost effective solution too since one system can be upgraded by software to perform many different functions. World-renown automakers such as Audi, BMW, Ford, GM, Mercedes-Benz, Toyota, and Volkswagen know this all too well, making Perceptron one of the biggest customers for the laser, camera, and processing hardware suppliers within their respective market niches.

All images courtesy of Perceptron.

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