In-situ 3D endoscopy based on fiber-optic fringe projection profilometry in production metrology

Abstract

The technological environment of industrial production processes faces constant challenges and is subject to continuous change. Requirements regarding resource and emission savings as well as lightweight construction, functionalization and individualization are key drivers of technical innovations. In particular, increasing automation, process monitoring and fast component inspection are of growing importance, which requires novel and innovative measurement approaches and instruments. In this thesis, a flexible, fiber-optic 3D endoscope based on fringe projection profilometry is presented for in-situ wear monitoring in operating forming processes. Due to specific measuring applications, different measuring head designs and positioning configurations are required. Flexible positioning necessitates strategies for registration of the reconstructed surface data in a fixed world coordinate system, which is investigated in the context of different approaches. Furthermore, algorithms and methods for adaptive data masking and improved data fusion are developed and presented, allowing for low-noise and accurate surface reconstruction while maintaining as many object points as possible. Complementary, methods for the reduction of inaccurate deviation values are developed to enable a high sensitivity and conclusiveness of the inspection. Furthermore, approaches for fast point cloud classification by adapted search trees and estimation methods are presented. Finally, the sensor is evaluated on the basis of existing standards and further developed approaches, and the influence of various environmental factors is investigated and quantified in various experiments.