A height calibration method and system based on a fixed-focus lens

Abstract

The invention belongs to the field of height calibration, and specifically discloses a height calibration method and system based on a prime lens. The method comprises the following steps of acquiringheight pixel values of different height calibration gauge blocks by using a prime lens assembly, acquiring distance pixel values from the centers of the different height calibration gauge blocks to the edge of a stage by using a telecentric lens assembly, calculating distance coefficients of each calibration gauge block by a distance coefficient calculation module based on the respective height pixel values and distance pixel values, determining a distance coefficient mean by a distance coefficient mean calculation module according to the distance coefficients of the respective calibration gauge blocks, calculating a conversion coefficient between the nominal height of the calibration gauge blocks and a height pixel value by a conversion coefficient calculation module, constructing a relationship model between the actual height and height pixel value and the distance pixel value based on the distance coefficients and the conversion coefficient, and realizing height measurement of a part to be tested by the model. The height calibration method and system provided by the invention have good applicability for height and thickness measurement of thin soft material parts, and can be developed for large-scale inspection on a production line.

Description

Technical field [0001] The invention belongs to the field of height calibration, and more specifically, relates to a height calibration method and system based on a fixed focus lens. Background technique [0002] The application of fixed focus lens in machine vision is very common. Its fixed angle of view can get a larger field of view and measurement range under the condition of long working distance. It is especially suitable for orthographic projection surfaces with large dimensions and low precision requirements. Automatic measurement occasions. However, for the measurement in the height direction, the working distance of the fixed focus lens changes due to the change of the length and width dimensions, and the observation size of the measuring object in the fixed focus field of view will change. The original method of calibrating image pixels at a fixed working distance will not be able to Meet the requirements of measurement accuracy. Therefore, it is necessary to re-stud...

AI Technical Summary

Problems solved by technology

However, for the measurement in the height direction, due to the change of the length and width, the working distance of the fixed-focus lens will change, and the observed size of the measured object in the fixed-focus field of view will change. The original method of calibrating image pixels with a fixed working distance will not be able to Meet the measurement accuracy requirements

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