134 S. Carter The new method also makes the test-up process much easier and faster because the practitioner no longer needs to track the accelerometer orientations, which has traditionally been an arduous process. It also eliminates the need to align triaxial accelerometers with the global coordinate system, simplifying the instrumentation process. These steps are eliminated from the test set-up process because the new method computes highly accurate local-to-global coordinate transformation matrices for all the accelerometers. The practitioner just needs to verify that the accelerometers are plugged in and labeled correctly in the channel set-up. As an example, the standard Sandia labeling convention for triaxial accelerometer channels is X+, Y+, and Z+for the X, Y, and Z channels, respectively. As such, labeling the channel directions in the channel table has been reduced to a simple copy and paste procedure. Lastly, the speed and reliability of the new method has made it sensible to measure test geometries solely for documentation purposes on tests that do not use test geometries. Examples of these test types include vibration testing, flight tests, and road load data acquisition. This eliminates the need to track accelerometer orientations (as described above) and provides a test set-up communication tool. This is a significant benefit because data from these test types can be handled by several people in different groups (such as environments engineers, analysts, test engineers, systems engineers, etc.) over long periods of time. Conclusions A method has been presented for generating a test geometry with PCMM probe data and an automated geometry generation script. It is significantly more accurate than the standard methods, especially hand measurements, which enables several benefits related to speed, reliability, and the ease of test set-up. The high level of automation also means that the practitioner can shift more of their focus to setting up and performing a fast and high-quality test, rather than expending significant effort to document the accelerometer directions and generate the test geometry. A common idiom is “price, speed, quality, pick two.” At a high level, it may seem that the PCMM based method only provides speed and quality. This method does require a high initial investment to purchase the PCMM and develop the geometry generation script. However, the time reductions in the test set-up and increased lab throughput could make the new method more cost effective than initially expected. Future efforts could focus on improving the method through more advanced data collection and processing techniques. The user must be able to reach the accelerometer with the probe tip in the PCMM based method, which can be challenging depending on part geometry. This could potentially be eliminated with non-contacting measurement techniques, such as a laser line probe or photogrammetry. The method could also be further automated through the use feature extraction techniques, so the practitioner does not need to provide accelerometer dimension data. It would also be informative to perform objective evaluations of the new method as compared to the industry standard methods, with a focus on speed and accuracy gains. The current evaluations were mostly subjective, with a single backto-back comparison. A more thorough study of the benefits could lead to a better application of the different geometry generation methods available to the practitioner (e.g., knowing when hand measurements or the PCMM are more convenient and faster to use). References 1. van der Seijs, M., Harvie, J., Song, D.: Road noise NVH: embedding suspension test benches in NVH design using virtual points and the TPA frame. In: Proceedings of IMAC XXXIX, the 39th International Modal Analysis Conference (2021) 2. Shakarji, C.: Least-squares fitting algorithms of the NIST algorithm testing system. J. Res. Nat. Inst. Stand. Technol. 103, 633–641 (1998) 3. Chernov, N., Lesory, C.: Least squares fitting of circles. J. Math. Imaging Vision. 23, 239–252 (2005) 4. 8-Axis QuatumS FaroArm/ScanArm V2 Specifications, 2020, [Online]. Available: https://downloads.faro.com/index.php/s/ pJdbrkR8X7Y5Cq8?dir=undefined&path=%2FEnglishUS&openfile=39313
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