Noncontact dimensional metrology by triangulation under laser plane lighting : development of new ambulatory instruments / Métrologie dimensionnelle sans contact par triangulation sous éclairage par plans laser : développement de nouveaux instruments ambulatoires

• Main Author: Demeyere, Michaël
• Format: Others
• Language: en
• Published: Universite catholique de Louvain 2006
• Subjects: Ambulatoire; Structured lighting; Eclairage structuré; Triangulation laser; Métrologie dimensionnelle
• Online Access: http://edoc.bib.ucl.ac.be:81/ETD-db/collection/available/BelnUcetd-03092006-140258/

Dimensional metrology is of prime importance in the industrial and scientific domains, particularly in the field of quality control of manufactured products. In robotics too: without dimensional sensors, robots would be nothing else more than automatons, going through the same repetitive tasks again and again in a carefully controlled environment. This thesis deals with a noncontact measurement technique involving active vision, called triangulation under laser plane lighting. This optomechatronic method consists in projecting a laser sheet on an object or a surface under test, and analyzing the intersecting curve on an image taken by a camera. It allows making a wide variety of dimensional, noncontact and nondestructive, measurements (length, area, volume, diameter, curvature, reverse engineering,...). The original approach of the work is that the focus is brought on the determination of specific, restricted dimensional information on objects of diverse, but a priori known, shapes with the objective of achieving metrological performances in agreement with the industrial requirements. Furthermore, ambulatory instruments­i.e. devices that are at least portable, or even handheld­are exclusively aimed, using low-cost components. Another objective is to obtain systems for which an industrial transposition to innovative instrumental products is feasible. The text is divided in two distinct parts, both strongly correlated. The first one deals with all the theoretical aspects of the method: camera model, passage from 2-D image to 3-D scene, image processing, calibration, accuracy analysis... The performances of the developed models are also studied, in terms of robustness and repeatability. The second part describes four innovative applications of our own: the diameter measurement of cylindrical and of spherical objects, dimensional measurements in the building sector and the determination of the road surface microtexture. The achieved accuracies are globally of about 1%.