Measuring pipe-undulation shape by laser-beam scanning pipe inner-wall-shape inspection sensor

Abstract

We have investigated reconstruction of the pipe-undulation shape throughout the length of a pipe from the measured data of the interior profiles by using a laser-beam scanning sensor. This sensor has been studied for detailed noncontact mapping of the interior geometry of pipes. The sensor, which is based on the optical triangulation, employs a laser-beam scanner placed between a laser diode and a position sensor. In this article, we develop a model for calculating a curvature of ridgeline on an inner wall of a pipe, and derive a formula to compute the curvature form of the pipe. By using this formula, it is possible to lead the whole pipe-undulation shape of the measured pipe in an iterative manner. Then we apply it to an actual measurement of a pipe, which was constructed for experiment. We find that the reconstruction is successful for the short section (up to 7 m) with expected accuracy (within about 20%) and we could derive a rough shape for a whole length of the conduit.

Keywords

• curvature measurement
• curved pipe
• pipe interior geometry mapping
• laser-beam scanning sensor
• optical triangulation