A temperature measurement method and system based on machine vision and negative thermal expansion structure

Abstract

This invention discloses a temperature measurement method and system based on machine vision and a negative thermal expansion structure, belonging to the field of temperature measurement technology. It rapidly measures temperature by utilizing the deformation caused by the thermal contraction and expansion of the negative thermal expansion structure. The method includes: placing the negative thermal expansion structure in the environment to be measured, with an industrial camera horizontally positioned alongside the structure; the industrial camera acquiring a deformation image and performing grayscale processing; binarizing the obtained grayscale image; performing edge detection and coordinate extraction on the acquired image; and calculating the temperature of the environment based on the deformation of the negative thermal expansion structure. The temperature measurement system includes: a negative thermal expansion structure, a lens, an industrial camera, and a camera mount; the industrial camera is placed on the camera mount and horizontally alongside the negative thermal expansion structure. This method solves the problem of distance affecting the measurement accuracy of temperature sensors, offering significant advantages for long-distance measurements and measurements of both high and low temperatures.

Description

Technical Field

[0001] This invention belongs to the field of temperature measurement technology, specifically relating to a temperature measurement method and system based on machine vision and negative thermal expansion structure. Background Technology

[0002] Currently, temperature detection technology is relatively mature. Common temperature detection methods include pressure-based temperature measurement, resistance temperature measurement, radiation temperature measurement, and infrared measurement. Pressure-based temperature measurement has a simple structure and high mechanical strength, but it suffers from significant heat loss and a slow response time; furthermore, pressure temperature sensors can only perform contact measurements. Thermocouple temperature measurement offers high accuracy and good reproducibility, but it requires an external power supply and cannot be used in environments with strong vibrations. Radiation temperature measurement can measure relatively high temperatures and has a fast response time, but the emissivity of the measured object and the absorptivity of the intermediate medium in the radiation channel can affect the measurement results.

[0003] Most materials have the property of thermal expansion and contraction. However, the thermal expansion and contraction of materials can accelerate the aging of machine parts, reduce their performance, and even cause the contact surfaces to separate and fall off. Using negative thermal expansion materials can greatly reduce the thermal stress caused by temperature changes.

[0004] To address the issues of temperature sensor measurement accuracy caused by heat loss and limitations in application scenarios in existing temperature detection methods, it is necessary to find a temperature measurement method that can obtain more accurate on-site temperatures in various situations and at both higher and lower temperatures. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a temperature measurement method and system based on machine vision and negative thermal expansion structure, so as to solve the problem that the measurement accuracy of temperature sensors is affected by heat loss and limited application scenarios in the prior art. It can quickly measure the temperature of the environment to be measured, and has obvious advantages for long-distance and short-distance measurement as well as high and low temperature measurement.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention discloses a temperature measurement method based on machine vision and negative thermal expansion structure, comprising the following steps:

[0008] The negative thermal expansion structure is placed in the test environment, and an industrial camera is placed horizontally alongside the negative thermal expansion structure. Deformation images are acquired using the industrial camera and then converted to grayscale. The resulting grayscale images are then binarized. Edge detection and coordinate extraction are performed on the binarized images. When the temperature changes, the negative thermal expansion structure contracts when heated and expands when cooled, resulting in shape changes and corresponding deformation. The temperature of the environment is calculated based on the deformation of the negative thermal expansion structure.

[0009] Preferably, the coefficient of thermal expansion of the negative thermal expansion structure satisfies the following relationship with temperature:

[0010] α = 2a / l(T - T0)

[0011] Where α is the coefficient of thermal expansion of the negative thermal expansion structure, a is the horizontal displacement of the vertex B of the I-shaped bimaterial rod after deformation relative to the center point o, l is the original length of the negative thermal expansion structure, T is the measurement temperature, and T0 is the original temperature.

[0012] More preferably, 'a' satisfies the following relationship with each component of the structural change of the negative thermal expansion structure:

[0013] a=u+hsinθ

[0014] Where u is half of the horizontal displacement of the I-shaped double material rod, h is the height of the I-shaped double material rod, and θ is the angle between point B and the vertical direction after the I-shaped double material rod is deformed.

[0015] Preferably, the total horizontal displacement of the negative thermal expansion structure and the horizontal displacement of half of the I-shaped bimaterial rod satisfy the following relationship:

[0016] u = x / 2m

[0017] Where x is the total horizontal displacement of the negative thermal expansion structure, and m is the number of single-row components of the I-shaped dual-material rod in the negative thermal expansion structure;

[0018] The sensor calculates the temperature value by identifying the total horizontal displacement x of the negative thermal expansion structure, without needing to identify the horizontal deformation u of a single I-shaped bimaterial rod.

[0019] More preferably, x satisfies the following relationship:

[0020] x = x1 + x2

[0021] Where x1 is the leftward contraction displacement of the negative thermal expansion structure in the horizontal direction when heated; x2 is the rightward contraction displacement of the negative thermal expansion structure in the horizontal direction when heated.

[0022] Preferably, the industrial camera is an infrared camera or a conventional camera.

[0023] Preferably, the negative thermal expansion structure is a cell-based negative thermal expansion structure.

[0024] Preferably, a dynamic threshold segmentation method is used for grayscale image binarization.

[0025] Preferably, the sensitivity of this temperature measurement method varies with the temperature sensitivity of the negative thermal expansion structure.

[0026] The present invention also discloses a temperature measurement system based on machine vision and negative thermal expansion structure used in the above temperature measurement method, including a negative thermal expansion structure and a vision mechanism;

[0027] The vision mechanism includes: a camera mount, an industrial camera mounted on the camera mount and placed horizontally with the negative thermal expansion structure, and a lens placed at the front end of the industrial camera.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This invention discloses a temperature measurement method based on machine vision and a negative thermal expansion structure. The negative thermal expansion structure is placed in the test environment. As the temperature of the environment changes, the negative thermal expansion structure undergoes thermal contraction and expansion, resulting in corresponding deformation. An industrial camera is placed horizontally alongside the negative thermal expansion structure to accurately capture its deformation image. The image is then converted to grayscale to simplify the matrix and improve computational speed. The resulting grayscale image is then binarized to obtain an image with a larger visual difference, facilitating edge detection and coordinate extraction. After obtaining the original coordinates and deformation coordinates of the negative thermal expansion structure, the deformation value of the structure is calculated. The temperature of the surrounding environment is then calculated based on this deformation value. By utilizing the property of thermal contraction and expansion of the negative thermal expansion structure under temperature changes, the temperature measurement is transformed into the measurement of the horizontal deformation displacement caused by temperature changes. This allows for relatively accurate on-site temperature measurement at a greater distance. Furthermore, the negative thermal expansion material generates less thermal stress during temperature changes, resulting in superior performance and significant advantages for long-distance and high-temperature measurements.

[0030] Furthermore, the industrial camera can be an infrared camera or a regular camera, and different cameras can be selected for different application environments. There are no restrictions on the types of cameras, and the selection range is wide. This setting expands the scope of application of this temperature measurement method.

[0031] Furthermore, the negative thermal expansion structure is unrestricted and can be any cell structure.

[0032] Furthermore, the detection method is based on machine vision recognition technology, and the sensitivity of the detection method varies with the temperature sensitivity of the negative thermal expansion material used.

[0033] This invention also discloses a temperature measurement system based on machine vision and a negative thermal expansion structure, including a negative thermal expansion structure and a vision mechanism composed of a lens, an industrial camera, and a camera bracket. The negative thermal expansion structure is placed in the environment to be measured, and the industrial camera is placed on the camera bracket and horizontally positioned with the negative thermal expansion structure. Due to temperature changes, the negative thermal expansion structure undergoes corresponding deformation. After accurately acquiring the deformation image, the industrial camera performs grayscale processing and grayscale image binarization, followed by edge detection and coordinate extraction to obtain the original coordinates and deformation coordinates, thereby obtaining the deformation of the negative thermal expansion structure. The ambient temperature is then obtained according to the relationship formula. This temperature measurement system based on machine vision and a negative thermal expansion structure offers flexible and diverse optional structures, a simple overall design, independent components, and no physical connection, effectively solving the problem in the prior art where the measurement accuracy of sensors is affected by intermediate medium transmission factors such as distance. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the temperature measurement system based on machine vision and negative thermal expansion structure disclosed in this invention.

[0035] Figure 2 This is a schematic diagram of the shape change of the negative thermal expansion structure of the present invention after thermal deformation;

[0036] Figure 3 This is a schematic diagram of the thermal deformation of the single-cell structure of the negative thermal expansion structure of the present invention.

[0037] Among them: 1- Negative thermal expansion structure; 2- Lens; 3- Industrial camera; 4- Camera bracket. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] The present invention will now be described in further detail with reference to the accompanying drawings:

[0041] The negative thermal expansion structure is placed in the test environment, and the industrial camera is placed on the camera bracket and placed horizontally with the negative thermal expansion structure.

[0042] Due to temperature changes, the negative thermal expansion structure undergoes corresponding deformation. After the industrial camera acquires the deformation image, it is processed into grayscale. The resulting grayscale image is then subjected to dynamic thresholding (grayscale image binarization) to obtain an image with a large visual difference, so as to perform edge detection and coordinate extraction. After obtaining the original coordinates and deformation coordinates, the deformation of the negative thermal expansion structure is obtained, and the ambient temperature is obtained according to the relationship.

[0043] See Figure 1 This is a schematic diagram of the temperature measurement system based on machine vision and negative thermal expansion structure disclosed in this invention. As can be seen from the figure, the temperature measurement system based on machine vision and negative thermal expansion structure includes a negative thermal expansion structure 1 and a vision mechanism composed of a lens 2, an industrial camera 3, and a camera bracket 4. The negative thermal expansion structure 1 is placed in the environment to be measured, the industrial camera 3 is placed on the camera bracket 4 and is placed horizontally with the negative thermal expansion structure 1, and the lens 2 is placed in front of the industrial camera 3. Due to temperature changes, the negative thermal expansion structure 1 undergoes corresponding deformation. The industrial camera 3 is placed horizontally with the negative thermal expansion structure 1. After accurately acquiring the deformation image, grayscale processing and grayscale image binarization are performed, followed by edge detection and coordinate extraction to obtain the original coordinates and deformation coordinates. Then, the deformation of the negative thermal expansion structure 1 is obtained, and the ambient temperature is obtained according to the relationship.

[0044] See Figure 2 This is a schematic diagram of the shape change of the negative thermal expansion structure after being heated and deformed. As can be seen from the figure, x1 is the leftward contraction displacement of the negative thermal expansion structure in the horizontal direction when heated; x2 is the rightward contraction displacement of the negative thermal expansion structure in the horizontal direction when heated.

[0045] See Figure 3This is a schematic diagram of the thermal deformation of the unit cell structure of the negative thermal expansion structure of the present invention. As can be seen from the figure, h is the height of the I-shaped double material rod, θ is the angle between point B and the vertical direction after the deformation of the I-shaped double material rod, l is the original length of the negative thermal expansion structure, and u is 1 / 2 of the horizontal displacement of the I-shaped double material rod.

[0046] This invention discloses a temperature measurement method based on machine vision and negative thermal expansion structure, specifically including:

[0047] S1. Place the negative thermal expansion structure 1 in the test environment. The negative thermal expansion structure 1 and the industrial camera 3 are placed horizontally. Due to temperature changes, the negative thermal expansion structure 1 will deform accordingly. The industrial camera 3 will collect the deformation image. The internal and external parameter matrix of the industrial camera 3 will be obtained through the calibration of the industrial camera 3. The image captured by the industrial camera 3 will be corrected.

[0048] S2 and industrial camera 3 acquire images before and after deformation, which are then processed by grayscale and grayscale binarization and transmitted to the computer processing module to obtain images with large visual differences in order to perform edge detection and coordinate extraction. After obtaining the original coordinates and deformation coordinates, the deformation of the negative thermal expansion structure 1 is obtained, and the horizontal displacement of the I-shaped rod is obtained.

[0049] S3. Utilizing the property that the negative thermal expansion structure 1 will shrink and expand when subjected to temperature changes, a relationship is established with the displacement generated in the horizontal direction, so that the temperature value is output through the relationship when the displacement is measured.

[0050] The relationship between the coefficient of thermal expansion and the deformation of negative thermal expansion structure 1 is as follows:

[0051] α = 2a / l(T - T0)

[0052] Where α is the coefficient of thermal expansion of the negative thermal expansion structure 1, a is the horizontal displacement of the vertex B of the I-shaped dual-material rod after deformation relative to the center point o, l is the original length of the negative thermal expansion structure 1, T is the measurement temperature, and T0 is the original temperature.

[0053] Furthermore, the relationship between a and the components of the structural change in the negative thermal expansion structure 1 is as follows:

[0054] a=u+hsinθ

[0055] Where u is half of the horizontal displacement of the I-shaped double material rod, h is the height of the I-shaped double material rod, and θ is the angle between point B and the vertical direction after the I-shaped double material rod is deformed.

[0056] Furthermore, the relationship between the total horizontal displacement of the negative thermal expansion structure 1 and the horizontal displacement of half of the I-shaped bimaterial rod is as follows:

[0057] u = x / 2m

[0058] Where x is the total horizontal displacement of the negative thermal expansion structure 1, and m is the number of single-row components of the I-shaped dual-material rod in the negative thermal expansion structure.

[0059] Furthermore,

[0060] x = x1 + x2

[0061] Where x1 is the leftward contraction displacement of the negative thermal expansion structure 1 in the horizontal direction when heated; x2 is the rightward contraction distance of the negative thermal expansion structure 1 in the horizontal direction when heated.

[0062] Industrial camera 3 can be either an infrared camera or a regular camera;

[0063] Negative thermal expansion structure 1 is a cell-based negative thermal expansion structure;

[0064] The grayscale image is binarized using a dynamic threshold segmentation method.

[0065] The detection method is based on machine vision recognition technology, and its sensitivity varies depending on the temperature sensitivity of the negative thermal expansion material used.

[0066] In summary, this invention provides a temperature measurement method and system based on machine vision and a negative thermal expansion structure for rapid temperature measurement, addressing the problem in existing technologies where sensor measurement accuracy is affected by factors such as distance and intermediate media transmission. The temperature measurement system based on machine vision and a negative thermal expansion structure can obtain relatively accurate on-site temperatures at greater distances. Furthermore, the negative thermal expansion material generates less thermal stress during temperature changes, resulting in superior performance and significant advantages for long-distance and high-temperature measurements. This temperature measurement system based on machine vision and a negative thermal expansion structure offers flexible and diverse structural options, a simple overall design, and independent components with no physical connections.

[0067] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A temperature measurement method based on machine vision and negative thermal expansion structure, characterized in that, Includes the following steps: The negative thermal expansion structure is placed in the test environment, and the industrial camera is placed horizontally with the negative thermal expansion structure; the deformation image is acquired using the industrial camera and then grayscale processed, and the resulting grayscale image is binarized. Then, edge detection and coordinate extraction are performed on the binarized image; When the temperature changes, the negative thermal expansion structure contracts when heated and expands when cooled, resulting in shape changes and corresponding deformation. The temperature of the environment can be calculated based on the deformation of the negative thermal expansion structure. The coefficient of thermal expansion of a negative thermal expansion structure satisfies the following relationship with temperature: in, The coefficient of thermal expansion of a structure with negative thermal expansion is... The vertex B of the deformed I-shaped bimaterial rod is relative to the center point. Horizontal displacement, This is the original length of the negative thermal expansion structure. To measure temperature, The original temperature; The components of the structural change of the negative thermal expansion structure satisfy the following relationship: in, The horizontal displacement of the I-shaped double-material rod is 1 / 2, and h is the height of the I-shaped double-material rod. Let B be the angle between point B and the vertical direction after the I-shaped bimaterial rod has deformed.

2. The temperature measurement method based on machine vision and negative thermal expansion structure according to claim 1, characterized in that, The total horizontal displacement of the negative thermal expansion structure and the horizontal displacement of half of the I-shaped bimaterial rod satisfy the following relationship: in, This represents the total horizontal displacement of the structure with negative thermal expansion. The number of single-row components of I-shaped bimaterial rods in a negative thermal expansion structure; The sensor calculates the temperature value by identifying the total horizontal displacement x of the negative thermal expansion structure, without needing to identify the horizontal deformation u of a single I-shaped bimaterial rod.

3. The temperature measurement method based on machine vision and negative thermal expansion structure according to claim 2, characterized in that, The following relationship must be satisfied: in, The negative thermal expansion structure contracts and shifts to the left in the horizontal direction when heated. The negative thermal expansion structure contracts and shifts to the right in the horizontal direction when heated.

4. The temperature measurement method based on machine vision and negative thermal expansion structure according to claim 1, characterized in that, Industrial cameras are either infrared cameras or ordinary cameras.

5. The temperature measurement method based on machine vision and negative thermal expansion structure according to claim 1, characterized in that, The negative thermal expansion structure is a cell-based negative thermal expansion structure.

6. The temperature measurement method based on machine vision and negative thermal expansion structure according to claim 1, characterized in that, A dynamic threshold segmentation method is used for grayscale image binarization.

7. The temperature measurement method based on machine vision and negative thermal expansion structure according to claim 1, characterized in that, The sensitivity of this temperature measurement method varies with the temperature sensitivity of the negative thermal expansion structure.

8. The temperature measurement method according to any one of claims 1 to 7 employs a temperature measurement system based on machine vision and a negative thermal expansion structure, characterized in that... Includes a negative thermal expansion structure (1) and a visual mechanism; The vision mechanism includes: a camera bracket (4), an industrial camera (3) placed on the camera bracket (4) and horizontally positioned with the negative thermal expansion structure (1), and a lens (2) placed at the front end of the industrial camera (3).

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