3-D Vision Measurement System and Method for Small-Diameter Pipeline

As precision key components, it is challenging to achieve high-precision measurements of the internal surface morphology and parameters of small-diameter pipelines because of their limited internal space. Most existing methods can achieve a rough evaluation of pipeline quality but it is difficult to meet the high-precision measurement requirements of small-diameter pipelines, and many methods cannot be applied due to the diameter limitations. In order to realize high-precision 3-D measurement in confined space, a novel 3-D vision measurement system and method for small-diameter pipeline is proposed in this article. Based on the principle prototype of the multicamera differential binocular vision sensor, a measurement system is constructed and the measurement method and algorithm are proposed based on the morphology and confined space of the small-diameter pipeline. The board-level industrial cameras combined with the structural parameter design enable the measurement system to be applied to the internal measurement of small-diameter pipelines. Experiments show that the proposed measurement system and method can achieve high-precision measurement of pipelines with diameters from 80 to 240 mm, with a diameter measurement accuracy of 0.035 mm, a coaxiality measurement accuracy of 0.066 mm, and a marker size measurement accuracy of 0.024 mm.