QMT Features: December 2009
Handheld scanners check crash dummies for accuracy
A hand-held laser scanner ensures the accuracy of crash dummies, crucial in evaluating the performance of side curtain airbags in a rollover.


First Technology Safety Systems, Inc. (FTSS) in the USA use the NVision HandHeld laser scanner to ensure the accuracy of crash dummies, which are crucial in evaluating the performance of side curtain airbags in a rollover. FTSS is the world's leading provider of crash test dummies and computer crash simulation models for automotive, military and aerospace applications.

The need for scanning arose when a mathematical formula was developed to define the geometry of a dummy, which, like many others, was originally based on a physical mold. "Crash dummies have been developed over the years largely as physical molds," said FTSS Engineer Steve Goldner. "The geometry of the dummy has a major impact on crash test results but it has become essential to convert the original designs to mathematical models in order to enable improvements in manufacturing technology. It also helps avoid damage to the original mold."

FTSS engineers designed a new dummy based on the mathematical model. Since physical measurement methods could not provide the level of accuracy needed to confirm that the new design matched dummies built from the original mold, they used laser scanning to measure the new dummy. FTSS selected the NVision HandHeld scanner for this task because of its wide-stripe laser, speed, accuracy, and ease of use. The scan data is quickly converted to an STL file, which can be easily compared to a computer aided design (CAD) model.

A key advantage of the HandHeld Scanner is that it is mounted on a mechanical arm so it can move freely around parts of any size. The mechanical arm keeps track of the scanner's location so all data is collected within the same coordinate system. As FTSS technicians scanned the dummy, the scanner generated a point cloud consisting of the coordinates of individual points. FTSS technicians used integrated software that comes with the scanner to convert the point cloud to an STL polygon mesh. Reverse engineering software then converted the STL data to a surface model. Then they overlaid both the scanned model and the CAD geometry based on the mathematical formula to see how closely they matched.

They used this process to fine-tune the mathematical formulae until they were able to create a new dummy and confirm it exactly reproduced the original mold designs. To date, FTSS has reverse-engineered between 30 and 40 dummies with the NVision HandHeld scanner. This process ensures that current test dummies are consistent with those used in the past, which in turn ensures the accuracy of the crash tests that are used to evaluate automobile safety.

email: sales@nvision3d.com
www.nvision3d.com
www.ftss.com
  
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