A smart flat-coil eddy-current sensor for metal-tag recognition

Abstract

This paper describes a smart eddy-current sensor for locating and identifying metal tags used to recognize buried pipes. We first describe the tags used and the technology of our locator, which is based on the induction-balance principle. We also describe an essential measurement-distance system controlling the sampling of data. An originality of the detector is the use of two flat coils carved onto an epoxy-resin support to generate the best possible electromagnetic field. The tags are made up of metal pieces of varying sizes separated by spaces of varying sizes. Intelligent pattern-recognition methods and their combination by the theory of evidence, which provide good and reliable recognition, are briefly presented. Finally, the system's performance for various depths of burial is analysed and ways to improve these results are presented.