Welding Joint Features Extraction Algorithm for Laser Triangulation Sensors Applied to Root Pass Control

Algoritmo de Extração das Características da Junta para Sensores de Triangulação Laser Aplicados ao Controle do Passe de Raiz

Abstract

Joint geometry measurement is a key task for welding automation. Among the sensors used for this purpose, the Laser Triangulation Sensors for welding (LTS) are the ones that best characterize the joint geometry. Root gap measurement is especially important for success in the automated root pass deposition, with production and quality benefits in different applications, such as pipeline construction for the Oil & Gas industry. The measurement of this feature is sensitive to noises generated by welding and joint surface reflexivity. The image processing algorithms for gap measurement available in literature do not have the desired characteristics of measurement error and flexibility for dimensional variability of welding joints. This paper presents a new algorithm for root gap measurement of “V” type joints using a linear adjustment technique. This developed algorithm was evaluated from measurement errors found in images captured before and during orbital welding procedure of a standard test piece. The same images were processed with pattern correlation algorithm and derivative algorithm, both presented in academic papers. The proposed algorithm presented the best results of measurement error, robustness and flexibility.

Key-words:
Adaptive welding; Control and welding automation; Intelligent systems; Orbital welding; Productivity