Device and method for measuring digital image of sample surface deformation based on sub-pixel angular point recognition

Abstract

The invention belongs to the technical field of digital image measurement and geotechnical engineering tests, and relates to a device and method for measuring a digital image of sample surface deformation based on sub-pixel angular point recognition. The measuring device is composed of a novel image measurement pressure chamber, a CMOS industrial camera, a camera bracket, a flexible lens hood, a computer and matched measurement software. The method comprises the steps of separating a sample into a plurality of four-node finite elements through squares printed on the sample, and angular pointsof the grid serve as nodes of the finite element; the deformation of feature points are tracked in real time based on edge detection and angular point recognition of sub-pixels; and whole-surface deformation information of the sample is captured through two plane mirror forming an angle of 120 degrees behind the sample, and splicing and error correction are performed on three images so as to realize deformation observation for the whole surface. The device and method are low in cost, simple in device, high in environmental applicability and high in measurement accuracy, can measure and track the deformation of the feature points in real time and obtain a deformation field and a strain field of the whole surface.

Description

technical field [0001] The invention belongs to the technical field of digital image measurement and geotechnical engineering test, and relates to a digital image measurement device and method for a sample surface based on sub-pixel corner point recognition. Background technique [0002] Deformation measurement of specimen is one of the most important contents in experimental mechanics, and it is also an important part of geotechnical engineering test. The traditional sample deformation measurement mostly uses measurement methods such as strain gauges, Hall effect sensors, local deformation measurement sensors, and eddy current sensors. These methods have the following disadvantages: (1) average measurement, (2) contact measurement, (3) The measurement accuracy is not high or there are few measurement points. At the same time, the overall deformation image of the sample cannot be obtained, and the strain field of the local arbitrary point deformation of the sample cannot be...

AI Technical Summary

Problems solved by technology

The traditional sample deformation measurement mostly uses measurement methods such as strain gauges, Hall effect sensors, local deformation measurement sensors, and eddy current sensors. These methods have the following disadvantages: (1) average measurement, (2) contact measurement, (3) The measurement accuracy is not high or there are few measurement points

At the same time, the overall deformation image of the sample cannot be obtained, and the strain field of the local arbitrary point deformation of the sample cannot be obtained, so it is difficult to study the local deformation characteristics of the sample; and, for the measurement environment under some special conditions, the measurement The means will have higher requirements, such as measuring the deformation of a soil sample in a water pressure container, the traditional measurement method will interfere with the sample, and it is very troublesome to operate in an underwater pressure environment

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