CN-116164854-B - Temperature measurement method and system based on machine vision and negative thermal expansion structure

CN116164854BCN 116164854 BCN116164854 BCN 116164854BCN-116164854-B

Abstract

The invention discloses a temperature measuring method and a temperature measuring system based on machine vision and a negative thermal expansion structure, which belong to the technical field of temperature measurement, and the temperature is rapidly measured through deformation quantity generated by thermal shrinkage and cold expansion of the negative thermal expansion structure; the industrial camera collects deformation images and carries out grey-scale treatment, the grey-scale images are binarized, edge detection and coordinate extraction are carried out on the obtained images, and the temperature of the environment is calculated according to the deformation quantity of the negative thermal expansion structure. The temperature measurement system comprises a negative thermal expansion structure, a lens, an industrial camera and a camera support, wherein the industrial camera is arranged on the camera support and is horizontally arranged with the negative thermal expansion structure. The problem that the measurement accuracy of the temperature sensor is affected due to the distance problem is solved, and the method has obvious advantages for long-distance measurement and measurement at higher temperature or lower temperature.

Inventors

ZHANG ZHENGKAI
LI PENGJU
WEN QINGGUO
MA YAWEN
ZHU JIANWEI
LU HONGJIE

Assignees

西安建筑科技大学

Dates

Publication Date: 20260505
Application Date: 20230228

Claims (8)

1. The temperature measurement method based on the machine vision and the negative thermal expansion structure is characterized by comprising the following steps of: The method comprises the steps of placing a negative thermal expansion structure in an environment to be detected, horizontally placing an industrial camera and the negative thermal expansion structure, collecting a deformation image by the industrial camera, carrying out gray-scale treatment, carrying out gray-scale image binarization on the obtained gray-scale image, carrying out edge detection and coordinate extraction on the image obtained by binarization, carrying out thermal shrinkage and cold expansion on the negative thermal expansion structure when the temperature changes, generating corresponding deformation quantity when the shape changes, and calculating the temperature of the environment according to the deformation quantity of the negative thermal expansion structure; the following relationship is satisfied between the thermal expansion coefficient and the temperature of the negative thermal expansion structure: Wherein, the Is the thermal expansion coefficient of the negative thermal expansion structure, The vertex B of the deformed I-shaped bi-material rod is opposite to the center point The displacement in the horizontal direction is used to move the movable element, Is the original length of the negative thermal expansion structure, In order to measure the temperature of the material, Is the original temperature; The following relationship is satisfied between each component in the structural change of the negative thermal expansion structure: Wherein, the 1/2,H of the horizontal displacement of the I-shaped bi-material rod is the height of the I-shaped bi-material rod, The included angle between the point B and the vertical direction after the deformation of the I-shaped dual-material rod.
2. The temperature measurement method based on machine vision and a negative thermal expansion structure according to claim 1, wherein the total displacement of the negative thermal expansion structure in the horizontal direction and the horizontal displacement of the 1/2I-shaped bi-material rod satisfy the following relationship: Wherein, the Is the total displacement of the negative thermal expansion structure in the horizontal direction, The number of single-row components of the I-shaped dual-material rod in the negative thermal expansion structure; the sensor calculates the temperature value by identifying the total displacement x of the negative thermal expansion structure in the horizontal direction, and does not need to identify the deformation u of the single I-shaped bi-material rod in the horizontal direction.
3. The method for measuring temperature based on machine vision and negative thermal expansion structure according to claim 2, wherein, The following relationship is satisfied: Wherein, the The negative thermal expansion structure is heated to shrink and displace at the left side in the horizontal direction; The negative thermal expansion structure is heated to shrink and displace on the right side in the horizontal direction.
4. The method of claim 1, wherein the industrial camera is an infrared camera or a normal camera.
5. The method of claim 1, wherein the negative thermal expansion structure is a cell structure negative thermal expansion structure.
6. The temperature measurement method based on the machine vision and the negative thermal expansion structure according to claim 1, wherein the gray image binarization processing is performed by a dynamic threshold segmentation method.
7. The method of claim 1, wherein the sensitivity of the method varies with the sensitivity of the negative thermal expansion structure to temperature.
8. The temperature measurement system based on the machine vision and the negative thermal expansion structure adopted by the temperature measurement method according to any one of claims 1-7 is characterized by comprising a negative thermal expansion structure (1) and a vision mechanism; The vision mechanism comprises a camera support (4), an industrial camera (3) which is arranged on the camera support (4) and is horizontally arranged with the negative thermal expansion structure (1), and a lens (2) which is arranged at the front end of the industrial camera (3).

Description

Temperature measurement method and system based on machine vision and negative thermal expansion structure Technical Field The invention belongs to the technical field of temperature measurement, and particularly relates to a temperature measurement method and system based on machine vision and a negative thermal expansion structure. Background At present, temperature detection technology is mature, and for temperature detection methods, pressure type temperature measurement, thermal resistance temperature measurement, radiation high temperature measurement and infrared measurement are available. The pressure type temperature measuring structure is simple, the mechanical strength is high, but the heat loss is large, the response time is slow, and the pressure type temperature sensor can only perform contact type measurement. The thermocouple has high temperature measurement accuracy and good reproducibility, but needs an external power supply and cannot be used in the occasion of organic vibration. The high temperature of radiation can be measured at a higher temperature, the response speed is high, but the radiation rate of the measured object and the absorption rate of the medium in the middle of the radiation channel can have a certain influence on the measurement result. Most materials have the property of thermal expansion and contraction, but the thermal expansion and contraction of the materials can accelerate the ageing of machine parts, the reduction of service performance and even the separation of contact surfaces, and the thermal stress caused by temperature change can be greatly reduced by adopting the negative thermal expansion material. Aiming at the problems of the existing temperature detection method that the measurement accuracy of the temperature sensor is affected due to heat loss, limitation of use occasions and the like, it is necessary to find a temperature measurement method capable of obtaining more accurate on-site temperature in various occasions and at higher temperature or lower temperature. Disclosure of Invention In order to overcome the defects of the prior art, the invention aims to provide a temperature measuring method and a temperature measuring system based on a machine vision and negative thermal expansion structure, which are used for solving the problem that the measuring precision of a temperature sensor is affected due to heat loss and use occasion limitation in the prior art, and can be used for rapidly measuring the temperature of an environment to be measured, and have obvious advantages for long-distance and short-distance measurement and high-temperature and low-temperature measurement. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: the invention discloses a temperature measurement method based on machine vision and a negative thermal expansion structure, which comprises the following steps: the method comprises the steps of placing a negative thermal expansion structure in an environment to be detected, horizontally placing an industrial camera and the negative thermal expansion structure, collecting a deformation image by the industrial camera, carrying out gray-scale treatment, carrying out gray-scale image binarization on the obtained gray-scale image, carrying out edge detection and coordinate extraction on the image obtained by binarization, carrying out thermal shrinkage and expansion on the negative thermal expansion structure when the temperature changes, generating corresponding deformation quantity when the shape changes, and calculating the temperature of the environment where the negative thermal expansion structure is located according to the deformation quantity of the negative thermal expansion structure. Preferably, the following relationship is satisfied between the thermal expansion coefficient of the negative thermal expansion structure and the temperature: α=2a/l(T-T0) wherein alpha is the thermal expansion coefficient of the negative thermal expansion structure, a is the displacement of the vertex B of the deformed I-shaped bi-material rod in the horizontal direction relative to the central point o, l is the original length of the negative thermal expansion structure, T is the measured temperature, and T 0 is the original temperature. Further preferably, the following relationship is satisfied between a and each component in the structural change of the negative thermal expansion structure: a=u+hsinθ Wherein u is 1/2,h of the horizontal displacement of the I-shaped dual-material rod, theta is the included angle between the point B and the vertical direction after the I-shaped dual-material rod is deformed. Preferably, the total displacement of the negative thermal expansion structure in the horizontal direction and the horizontal displacement of the 1/2I-shaped bi-material rod satisfy the following relationship: u=x/2m Wherein x is the total displacement of the negative thermal