Calibration method and device for a line structured light sensor based on mechanical motion

Abstract

The invention relates to a calibration method for a line-structured light sensor based on mechanical movement and a device. The device comprises a camera, a laser, a calibration plane and a movement mechanism. The method comprises the steps that 1) a z-axis of a world coordinate system taking the calibration plane as the ground acts as the vertical direction, an intrinsic parameter A of the camera and an extrinsic parameter of a first checkerboard are acquired by using Zhengyou Zhang checkerboard calibration, and included angle alpha between a z-axis of a camera coordinate system and the vertical direction is acquired by using the extrinsic parameter; 2) the distance between corresponding points on adjacent laser stripes and corresponding image point coordinates are calculated; 3) a normal vector of a structured light plane is solved; and 4) an included angle theta between the structured light plane and the vertical direction is calculated according to the normal vector acquired in the step 3) and the included angle alpha between the z-axis of the camera coordinate system and the vertical direction, and the coordinates of a point on the structured light plane in the camera coordinate system are further acquired so as to complete calibration for a structured light plane equation.

Description

technical field [0001] The invention belongs to the technical field of measurement and relates to the improvement of a structured light parameter calibration method. Background technique [0002] The structured light visual inspection method has the advantages of large range, non-contact, large field of view and good system flexibility. It has been widely used in industrial environments, especially in the field of welding in recent years. The calibration of structured light parameters mainly uses the internal parameters of the camera and other auxiliary tools to determine the plane equation of the light plane in the camera coordinate system. The purpose of the line structure cursor calibration is to reconstruct the three-dimensional world coordinates from the two-dimensional image coordinates to realize three-dimensional measurement. [0003] There are currently several methods for calibrating structured light sensors: one is the sawtooth target. Due to the sawtooth reflec...

AI Technical Summary

Problems solved by technology

Due to the sawtooth reflection, the accuracy of the image points extracted by this method is poor, and external equipment is required to strictly adjust the light plane to be perpendicular to a certain reference plane, which is not suitable for on-site calibration; the second is the mechanical adjustment method

However, this method has many artificial adjustment links and the accuracy is not high.

The third is the filament scattering method, but the accuracy of this method is not high and the calibration process is more complicated. The fourth is the planar target method based on free movement, which is more commonly used

This method needs to solve nonlinear equations with constraints, and introduces nonlinear optimization. The method is complicated, slow, sensitive to initial value selection and noise, and cannot guarantee that the parameters converge to the global optimum.

Images