Hardware and Signal Processing for a Novel Multi-Lap-Joint Measurement System for Automated Welding Applications

• Published in: IEEE transactions on instrumentation and measurement 2014-12, Vol.63 (12), p.3096-3110
• Main Authors: Schrattenecker, Jochen O., Schuster, Stefan, Scheiblhofer, Werner, Reinthaler, Gunther, Ennsbrunner, Helmut, Stelzer, Andreas
• Format: Article
• Language: English
• Subjects: Accuracy; Algorithms; Arc welding; Automated; Computer simulation; Hardware; Industry applications; Millimeter wave radar; Polarization; Position control; Radar; Radar signal processing; Welding
• ISSN: 0018-9456; 1557-9662
• DOI: 10.1109/TIM.2014.2326275

This paper presents a radar system for measuring the position of edges with good electrical conductivity in automated welding applications. The sensor consists of a frequency-modulated continuous-wave radar system which operates in the W-band. To estimate the position of the edge, we focus on polarimetric scattering effects introduced by discontinuities in the shape of a conducting plate. In addition to hardware designs, we propose signal models for single- and multi-step scenarios. The signal models are calculated using a field simulation tool we developed. The proposed models were used to derive a novel position estimation algorithm that allows real-time operation. Further, the accuracy limits of our concept were investigated using an analytically derived Cramér-Rao lower bound and simulations for multi-step scenarios. The simulation results were verified by measurements. Electromagnetic influences of the welding arc on the system during operation were also investigated by measurements.