A Calibration Method for 3D Visual Inspection Based on Single Camera

Abstract

The invention discloses a calibration method for three-dimensional vision detection based on a single camera. The method adopts a single camera and an automatic focusing lens to automatically complete three-dimensional calibration in a multi-layer calibration manner, specifically including using a calibration board to perform multi-dimensional calibration in the direction of the imaging optical axis. Layer discrete calibration and calibration audit with calibration audit device, the final calibration error of the system after audit is less than two pixel units, which provides accuracy guarantee for 3D inspection with single camera in some occasions, simplifies 3D inspection structure and reduces equipment complexity degree.

Description

technical field [0001] The invention relates to the field of machine vision automatic processing, in particular to a single-camera-based calibration method for three-dimensional vision detection. Background technique [0002] In the field of laser precision welding, it is often necessary to weld the three-dimensional trajectory in space. Due to the concentration of laser energy and the easy deformation of the product to be welded, the allowable position offset during welding is small, and the general welding system cannot guarantee the welding quality. For this reason, a vision system is often used for three-dimensional detection of the position of the weld. The existing solution is to measure in three dimensions with two cameras or use binocular stereo vision for measurement. The welding seam positioning method using a single camera is mainly a seam tracking system, but this method requires the seam to have certain characteristics, such as straight seam, arc-shaped seam, et...

AI Technical Summary

Problems solved by technology

The welding seam positioning method using a single camera is mainly a seam tracking system, but this method requires the seam to have certain characteristics, such as straight seam, arc-shaped seam, etc., the seam recognition efficiency is low, and the system cannot quickly acquire The complete path of special-shaped welds, not suitable for high-speed laser welding

[0003] Invention patent "A Method of Focusing and Ranging Based on a Single Camera" (CN101858741A) uses imaging systems at different object distances to calculate the distance of an object, relying on finding matching pixels in close-up images and long-range images at different object distances point, the product needs to have uniquely identifiable features, such as the need to identify a straight weld on a horizontal plane, this system cannot achieve

Moreover, this method is aimed at image processing of a single imaging surface, and cannot calibrate the imaging parameters of each spatial layer within a specified spatial range, and is not suitable for visual inspection of three-dimensional workpieces.

The invention patent "A Distance Measuring Device Based on a Focusing Camera and Its Application Method" (CN201710949345A) is applied to the distance measurement of the grain depot environment, and the measurement accuracy is greater than 5mm. This method is not suitable for trajectory measurement or industrial precision measurement

There is no perfect 3D calibration method based on single camera

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