Automated Measurement Grid Generation for Scanning Laser Doppler Vibrometers

Abstract

Full field measurement techniques can provide fast, accurate and detailed vibration response data for finite element model validation and are being wildly used in industrial applications. A Scanning Laser Doppler Vibrometer (SLDV) measures the full field operating deflection shapes of a structure by changing the location of the laser spot on the target surface. However the setup of a measurement and in particular the measurement grid definition, can take up a significant part of the overall measurement time. To optimise the setup time a novel technique for SLDV measurement grids has been developed. The suggested method includes an automated identification of the vibrating target, based on the measured vibration signal of a scan covering the entire field of view of the LDV. Alpha-shape techniques for target identification and geometric algorithms for shape recognition are used to define the measurement area. Novel approaches for symmetry and orientation capture allow the generation of point grids and continuous patterns for various target shapes. The introduced approach allows a quick SLDV setup of the full field scan with a minimum input from the user.