A Robotic Line Scan System with Adaptive ROI for Inspection of Defects over Convex Free-form Specular Surfaces

TL;DR

This paper introduces a robotic inspection system for free-form specular surfaces that uses adaptive ROI scanning, surface segmentation, and robust registration to detect defects accurately.

Contribution

It presents a novel integrated approach combining adaptive ROI, surface segmentation, and registration for defect inspection on complex specular surfaces.

Findings

Effective defect detection demonstrated on free-form surfaces

Robust object localization using ICP-based registration

Adaptive scanning improves inspection accuracy

Abstract

In this paper, we present a new robotic system to perform defect inspection tasks over free-form specular surfaces. The autonomous procedure is achieved by a six-DOF manipulator, equipped with a line scan camera and a high-intensity lighting system. Our method first uses the object's CAD mesh model to implement a K-means unsupervised learning algorithm that segments the object's surface into areas with similar curvature. Then, the scanning path is computed by using an adaptive algorithm that adjusts the camera's ROI to observe regions with irregular shapes properly. A novel iterative closest point-based projection registration method that robustly localizes the object in the robot's coordinate frame system is proposed to deal with the blind spot problem of specular objects captured by depth sensors. Finally, an image processing pipeline automatically detects surface defects in the captured high-resolution images. A detailed experimental study with a vision-guided robotic scanning system is reported to validate the proposed methodology.