3D Vision Measurement System for Internal Surface of Slender Pipeline

Slender pipeline structures are widely used in industrial fields, where defects on their internal surfaces directly impact equipment safety and service life. Existing methods for 3D measurement of internal surface in slender pipelines face limitations such as incomplete 360° coverage and accumulated pose errors over long distances. To address these problems, this paper proposes a multi-sensor fusion 3D vision measurement system. The system integrates a structured light vision sensor, a pose measurement unit, and a motion control unit. The structured light vision sensor reconstructs complete single cross-section by synchronously capturing the internal laser stripe with multiple cameras and stitching the multi-view data. The pose measurement unit utilizes a laser rangefinder to project a positioning spot onto a flat plate, while a camera captures the spot image and an inclinometer provides attitude data, enabling pose measurement. The motion control unit drives the axial movement of the measurement system along the pipeline. To achieve global integration, data from the pose measurement unit enable the transformation of local cross-sections into a unified global coordinate system. In simulation experiments on a slender pipeline with a diameter of 155 mm and a length of 1000 mm, the system achieved a pipeline diameter measurement accuracy of 0.01 mm and an RMSE of 0.74 mm for the reconstructed internal surface point cloud.