TY - THES

T1 - Autonomous crack detection on ring joint surfaces of tubing elements

AU - Pogats, Jakob

N1 - embargoed until 27-10-2021

PY - 2016

Y1 - 2016

N2 - This Master thesis documents the development, testing and deployment of an autonomous camera system. This system can be used to record the crack development in TBM tubing elements during full scale load tests. A DSLR camera is mounted on a motorized linear guidance both controlled by a program on an industrial computer. To cover a larger area of the tubing’s ring joint surface, the linear guidance changes the position of the camera table and thereby alters the picture section. The ring joint surface is recorded after the completion of each load step. The pictures are then prepared to be analyzed using a SIFT algorithm, a Brute-Force Matcher and a homography estimation implemented in the software. The program detects significant features in the picture and monitors changes in the relative position of these features between different load steps. In zones with plastic deformation or around a crack, the relative distance changes between these features are greater than the changes in neighboring positions. The software uses a color scale to highlight these areas. The cracks can then be analyzed to determine opening angle, crack width, crack length and the course of the crack. The same program controlling the motorized linear guidance was also used to transfer the position and orientation of a total station. The objective of this application is to use a total station or a 3D laser scanner on a vertically mounted linear guidance in a TBM rear carriage. The instrument can pass through all levels of the TBM and transformation parameters between different levels can be determined. These can be used to register 3D laser scans. The 3D scanners are used to monitor and document the deformation of the outer liner. Due to the obstructed visibility and limited space in a TBM rear carriage, more than one 3D scan is necessary to record the entire cross section of the tunnel. The linear guidance system has the advantage of being compact and the potential to get all 3D scans in one coordinate system. This simplifies the procedure of using multiple 3D scans.

AB - This Master thesis documents the development, testing and deployment of an autonomous camera system. This system can be used to record the crack development in TBM tubing elements during full scale load tests. A DSLR camera is mounted on a motorized linear guidance both controlled by a program on an industrial computer. To cover a larger area of the tubing’s ring joint surface, the linear guidance changes the position of the camera table and thereby alters the picture section. The ring joint surface is recorded after the completion of each load step. The pictures are then prepared to be analyzed using a SIFT algorithm, a Brute-Force Matcher and a homography estimation implemented in the software. The program detects significant features in the picture and monitors changes in the relative position of these features between different load steps. In zones with plastic deformation or around a crack, the relative distance changes between these features are greater than the changes in neighboring positions. The software uses a color scale to highlight these areas. The cracks can then be analyzed to determine opening angle, crack width, crack length and the course of the crack. The same program controlling the motorized linear guidance was also used to transfer the position and orientation of a total station. The objective of this application is to use a total station or a 3D laser scanner on a vertically mounted linear guidance in a TBM rear carriage. The instrument can pass through all levels of the TBM and transformation parameters between different levels can be determined. These can be used to register 3D laser scans. The 3D scanners are used to monitor and document the deformation of the outer liner. Due to the obstructed visibility and limited space in a TBM rear carriage, more than one 3D scan is necessary to record the entire cross section of the tunnel. The linear guidance system has the advantage of being compact and the potential to get all 3D scans in one coordinate system. This simplifies the procedure of using multiple 3D scans.

KW - tubing test

KW - crack detection

KW - linear guidance

KW - autonomous camera

KW - SIFT

KW - features

KW - Brute-Force matcher

KW - homography

KW - crack development

KW - ring joint surface

KW - 3D-Scanner

KW - 3D scan

KW - Tübbingtest

KW - Risserkennung

KW - Linearführung

KW - autonomes Kamerasystem

KW - SIFT

KW - signifikante Punkte

KW - Brute-Force matcher

KW - Projektivität

KW - Rissausbreitung

KW - Ringfuge

KW - 3D-Scanner

KW - 3D Scan

KW - Niklasdorf

KW - Tübbingprüfstand

M3 - Master's Thesis

ER -