An automatic temperature calibration device and calibration method based on infrared thermal imaging technology

Abstract

The present invention provides a temperature automatic calibration device and calibration method based on infrared thermal imaging technology. The steps are as follows: determine the test temperature and test distance, and the host computer respectively issues a check temperature instruction and a check distance instruction; the blackbody control lower computer adjusts the temperature of the blackbody to the test temperature; the motion control lower computer drives the infrared detector to move until the distance between the infrared detector and the blackbody reaches the test distance; the host computer issues a grab infrared image instruction, and the infrared detector collects an infrared image; the host computer performs non-uniformity correction processing on the infrared image to obtain a corrected infrared image, and further uses an image enhancement algorithm to remove the noise of the image; interpolation processing is performed on each pixel in the denoised infrared image to obtain the final temperature value of the blackbody. The present invention has a good automation level, can effectively solve the problems of cumbersome process and low efficiency in the manual infrared thermal imaging temperature calibration process; has good accuracy and has a good application effect in the industrial environment.

Description

Technical Field

[0001] The present invention relates to the technical field of temperature calibration, and in particular to an automatic temperature calibration device and a calibration method based on infrared thermal imaging technology. Background Art

[0002] Infrared thermal imaging temperature measurement technology converts the invisible infrared energy emitted by an object into a visible thermal image. Different colors in the thermal image represent different temperatures of the object being measured. As the distance between the infrared thermal imaging temperature measurement device and the object being measured increases, the heat energy radiated by the object being measured will gradually decay, causing the temperature detected by the temperature measurement device at a distance to be lower than the actual temperature, and the accuracy is reduced, making it difficult to meet the application requirements of high-precision temperature measurement. Therefore, in order to avoid the influence of distance on radiation temperature measurement, it is necessary to establish a compensation model for temperature measurement attenuation, and it is usually necessary to consider temperature compensation and calibration at different temperatures of the object being measured and at different distances. Existing infrared thermal imaging temperature measurement calibration usually uses manual methods to adjust the blackbody temperature and the movement of the infrared thermal imaging temperature measurement device, and it is necessary to manually record the blackbody temperature, distance, and detection temperature parameters. This process is relatively cumbersome and consumes a lot of manpower and material resources. Therefore, how to realize an automatic temperature calibration device based on infrared thermal imaging technology to replace manual temperature detection and recording has become a technical problem that needs to be solved in this field. Summary of the invention

[0003] In view of the technical problem that the existing infrared thermal imaging temperature measurement calibration still requires manual participation and the process is cumbersome and inefficient, the present invention proposes an automatic temperature calibration device and calibration method based on infrared thermal imaging technology. Through the cooperation of the upper computer and the lower computer, the blackbody temperature and position are automatically adjusted and the infrared thermal imaging temperature measuring device is moved, thereby realizing automatic temperature detection and recording at different distances under different blackbody temperatures and positions, improving the automation level of infrared thermal imaging temperature measurement, and solving the problem of low efficiency of existing manual infrared thermal imaging temperature calibration.

[0004] In order to achieve the above object, the technical solution of the present invention is implemented as follows: a temperature automatic calibration method based on infrared thermal imaging technology, the steps of which are as follows:

[0005] Step 1: Determine the initialized test temperature t and test distance d. The upper computer sends a temperature verification instruction to the blackbody control lower computer according to the test temperature, and the upper computer sends a distance verification instruction to the motion control lower computer according to the test distance;

[0006] Step 2: After the blackbody control lower computer receives the temperature verification instruction sent by the upper computer, it compares the current temperature T of the blackbody with the test temperature t in the temperature verification instruction, and adjusts the temperature of the blackbody to the test temperature t;

[0007] Step 3: The lower-level motion control unit drives the infrared detector to move according to the distance verification instruction until the distance between the infrared detector and the blackbody reaches the test distance;

[0008] Step 4: The lower-level blackbody control unit issues a start / stop command and sends the current position to the upper-level computer, triggering the upper-level computer to issue an instruction to capture an infrared image. The infrared detector captures an infrared image of the test temperature of the blackbody at the current test distance, and the lower-level motion control unit uploads the captured infrared image to the upper-level computer;

[0009] Step 5: The upper-level computer performs non-uniformity correction on the obtained infrared image to obtain a corrected infrared image, and further removes image noise to improve the image quality;

[0010] Step 6: Interpolation processing is performed on each pixel in the infrared image with improved image quality, and the temperature values of each pixel are extracted and averaged to obtain the final temperature value of the current blackbody at the test temperature and test distance.

[0011] The upper-level computer is connected to the lower-level blackbody control unit and the lower-level motion control unit respectively based on the HTTP protocol; the verification temperature instruction of the test temperature is transmitted in the JSON file format, and the upper-level computer uses the HTTP protocol to send the verification temperature instruction to the lower-level motion control unit in the JSON format; the corrected infrared image is denoised using an image enhancement algorithm to improve the image quality for better visualization display of high-quality infrared images.

[0012] The verification temperature instruction or verification distance instruction in the JSON format includes id, type, value, and timestamp. Among them, id is the authentication code of an instruction, type is the flag for calibrating the instruction type, type = 0 represents that the instruction type is the blackbody temperature adjustment instruction, type = 1 represents that the instruction type is the distance adjustment instruction, value is the temperature or distance parameter value passed by the instruction, and timestamp is the time stamp used to record the time point when the instruction is sent.

[0013] The method for the lower-level blackbody control unit to adjust the temperature of the blackbody in Step 2 is as follows: The lower-level blackbody control unit obtains the current temperature T of the blackbody through the serial port protocol. If the current temperature T is consistent with the test temperature t, it enters Step 3; if the current temperature T is inconsistent with the test temperature t, the lower-level blackbody control unit sends a control temperature to the main controller of the blackbody to automatically adjust the temperature. When the current temperature T is greater than the test temperature t, the lower-level blackbody control unit automatically issues a cooling instruction through the serial port protocol; when the current temperature T is less than the test temperature t, the lower-level blackbody control unit automatically issues a heating instruction through the serial port protocol; after waiting for the blackbody to reach the test temperature t, the completion instruction is fed back to the upper-level computer via the HTTP protocol, and the upper-level computer issues a temperature verification instruction to the lower-level blackbody control unit again until the current temperature T is consistent with the test temperature t.

[0014] The implementation method for the motion control lower computer to drive the infrared detector to move in Step 3 is as follows: The laser rangefinder in the motion control lower computer is used to measure the actual distance D between the infrared detector and the black body. If the actual distance D is consistent with the test distance d, the motion control lower computer issues an encoder motor stop command and feeds back the result to the upper computer via the HTTP protocol. If the actual distance D is inconsistent with the test distance d, the motion control lower computer controls the trigger switch of the relay and controls the movement of the encoder motor II according to the test distance d. When the actual distance D is greater than the test distance d, the encoder motor II automatically executes a forward command. When the actual distance D is less than the test distance d, the encoder motor automatically executes a backward command. After the distance verification command is completed, the upper computer issues a distance verification command to the motion control lower computer again until the actual distance D is consistent with the test distance d.

[0015] The method for capturing black body pictures using the single black body spatial and time division multiplexing method in Step 4 is as follows: Before the upper computer issues a picture capture command to the infrared detector, the upper computer issues a motion control command to the black body control lower computer. The black body control lower computer takes spatial division measures to move the black body to the upper left corner, lower left corner, lower right corner, and upper right corner of the captured picture of the 320*240 pixel matrix respectively, and stops moving when it reaches the upper left corner, upper right corner, lower left corner, or lower right corner of the pixel of the captured infrared picture, and then notifies the upper computer to issue a picture capture command. During the picture capture process, 6 pictures are continuously captured in a time division manner to ensure that more black body pictures at different angles are captured at the current temperature and distance, and the captured pictures are uploaded to the upper computer. The method for moving the black body is to control the automatic adjustment device to move according to the actual distance corresponding to each pixel unit at different preset positions. The upper computer queries the actual distance that needs to be moved at the pixel position of the current black body in the infrared detector in the database. The average value of the temperature values of the black body in the 24 captured pictures is used as the final temperature value of the current black body position.

[0016] The method for non-uniformity correction processing is: Based on the gain and offset of non-uniformity correction for the maximum and minimum black body temperatures, temperature correction processing is performed. The correction formula is as follows: a[i] = g[i] * n[i] + o[i], where, is the gain coefficient; is the offset coefficient; n[i] is the pixel value to be calibrated; a[i] is the calibrated pixel value; in g[i] and o[i], d represents the difference between the mean value of all pixels at the maximum temperature and the mean value of all pixels at the minimum temperature, d1 represents the difference between the mean value of pixels at the minimum temperature and the mean value of pixels of the object to be corrected, and d2 represents the difference between the mean value of pixels of the object to be corrected and the mean value of all pixels at the maximum temperature; h represents the mean value of all pixels at the maximum temperature, l represents the mean value of all pixels at the maximum temperature, n represents the mean value of all pixels of the object to be corrected, and i represents the value of the pixel at the corresponding position; According to the usage experience accumulated usually, know the temperature difference range of the object to be measured, so as to determine the maximum temperature and the minimum temperature.

[0017] The image enhancement algorithm is as follows: perform hierarchical processing on the saliency of the target region M and the background B of the black body in the infrared image, set the priority MG and weight value MW of the gray level of the target region to be greater than the priority BG and weight value BW of the gray level of the background, adjust the contrast between the black body target and the background, and enhance the saliency of the black body target region; perform two non-subsampled shearlet transforms on the enhanced infrared image, decompose it into a low-pass subband image and a band-pass subband image, and fuse the two low-pass subband images according to the low-pass subband fusion strategy Fuse the two band-pass subband images according to the band-pass subband fusion strategy Finally, inverse transform through NSST to obtain the fused infrared image; where, C j0 (m,n) is the low-pass subband coefficient, C j,l (m,n) is the band-pass subband coefficient, j represents the decomposition scale, l represents the decomposition direction, and (m,n) represents the position of the pixel, represents the fused low-pass subband coefficient, is the fused band-pass subband coefficient, ω I1 、ω 12 represent the proportion coefficients of each low-pass subband fusion when the two low-pass subbands are fused, is the low-pass subband coefficient of image I1, is the low-pass subband coefficient of image I2, is the band-pass subband coefficient of image I2, is the band-pass subband coefficient of image I1;

[0018] Record the final temperature value of the blackbody at the set test distance and test temperature in the current constant temperature environment. The host computer automatically issues a new verification position command. The test position is incremented automatically based on the previous test position, and the single increment value is set to Δk meters. When the distance set by the host computer reaches the maximum distance K2 meters, the host computer sends a reset command to the motion control lower computer, and the reset distance is the nearest distance K1 meters, completing the temperature detection at different test distances under the current blackbody test temperature; the host computer continues to issue a new test temperature, and the test temperature is incremented based on the previous test temperature setting. The single increment value is set to Δt °C until the test temperature reaches the upper limit of the blackbody temperature (t + Δt °C), completing the automatic temperature detection and recording at different blackbody temperatures and different distances.

[0019] A calibration device using a temperature automatic calibration method based on infrared thermal imaging technology, including a host computer, a blackbody control lower computer, and a motion control lower computer. The host computer is connected to the blackbody control lower computer and the motion control lower computer respectively through network communication. The blackbody control lower computer is connected to the blackbody. An automatic adjustment device is provided under the blackbody, and the automatic adjustment device is connected to the blackbody control lower computer; the motion control lower computer is respectively connected to a calibration mechanism, a laser rangefinder, and a moving mechanism. The calibration mechanism is arranged above the motion control lower computer, and the laser rangefinder is arranged corresponding to the calibration mechanism up and down. The laser rangefinder is used to measure the distance between the blackbody and the calibration mechanism. The motion control lower computer is connected to the moving mechanism through a relay.

[0020] The automatic adjustment device includes a horizontal sliding mechanism and a vertical lifting mechanism. The vertical lifting mechanism is slidably arranged in the horizontal sliding mechanism. Encoder motors are provided in both the horizontal sliding mechanism and the vertical lifting mechanism. The blackbody control lower computer adjusts the left - right movement of the blackbody by controlling the forward or reverse rotation of the encoder motor in the horizontal sliding mechanism, and adjusts the up - down movement of the blackbody by controlling the forward or reverse rotation of the encoder motor in the vertical lifting mechanism; an encoder motor II is provided in the moving mechanism. The motion control lower computer adjusts the distance between the calibration mechanism and the blackbody by controlling the rotation of the encoder motor II; the calibration mechanism includes an infrared detector, a controller, and a data processing module. The controller is respectively connected to the data processing module, the infrared detector, and the motion control lower computer. The data processing module realizes the verification of the distance, and the controller controls the infrared detector to capture infrared images according to the control instruction.

[0021] The lower computer for blackbody control adjusts the blackbody temperature through a custom serial port protocol. The custom serial port protocol is used to connect the lower computer for blackbody control to the blackbody, and can both obtain and adjust the blackbody temperature. Common commands are as follows: Start / Stop: 10 60 00 10 00 10 91 AC / 10 60 00 10 00 00 8D A0; Set temperature to 0°C: 1066 00 A0 00 00 9A 8C; Read the current temperature: 10 30 00 C0 00 10 44 90.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) The present invention has a relatively high level of automation and can effectively solve the problems such as the cumbersome process and low efficiency in the manual infrared thermal imaging temperature calibration process.

[0024] (2) The present invention has good accuracy and has good applicability in temperature measurement and calibration in an industrial environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0026] Figure 1 It is a schematic flow chart of the infrared thermal imaging temperature automatic calibration method of the present invention.

[0027] Figure 2 It is a schematic structural diagram of the infrared thermal imaging temperature automatic calibration device of the present invention.

[0028] Figure 3 It is a schematic diagram of the data transmission format of the present invention.

[0029] Figure 4 It is a flow chart of the blackbody temperature verification of the present invention.

[0030] Figure 5 It is a flow chart of the distance verification of the present invention.

[0031] Figure 6 It is a position diagram of the blackbody movement of the present invention.

[0032] Figure 7 It is an effect diagram of the infrared image capture of the present invention.

[0033] Figure 8 It is a processing flow chart of the image enhancement algorithm of the present invention.

[0034] Figure 9 This is the original image captured by the blackbody of the present invention.

[0035] Figure 10 is Figure 9 The effect diagram of the blackbody after image enhancement processing. Specific implementation manners

[0036] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] Embodiment 1

[0038] As Figure 2 shown, a temperature automatic calibration device based on infrared thermal imaging technology includes a host computer, a blackbody control slave computer, and a motion control slave computer. The host computer is connected to the blackbody control slave computer and the motion control slave computer respectively through network communication. The blackbody control slave computer is connected to the blackbody. An automatic adjustment device is provided below the blackbody, and the automatic adjustment device is connected to the blackbody control slave computer. The automatic adjustment device includes a horizontal sliding mechanism and a vertical lifting mechanism. The vertical lifting mechanism is slidably disposed in the horizontal sliding mechanism. Encoder motors are provided in both the horizontal sliding mechanism and the vertical lifting mechanism. The blackbody control slave computer adjusts the up, down, left, and right movement of the blackbody by controlling the forward or reverse rotation of the encoder motor. The motion control slave computer is respectively connected to a calibration movement mechanism, a laser rangefinder, and a moving mechanism. The calibration movement mechanism is disposed above the motion control slave computer. The laser rangefinder is disposed corresponding to the calibration movement mechanism up and down. The laser rangefinder is used to measure the distance between the blackbody and the calibration movement mechanism. The motion control slave computer is connected to the moving mechanism through a relay. An encoder motor is provided in the moving mechanism. The motion control slave computer adjusts the distance between the calibration movement mechanism and the blackbody by controlling the rotation of the encoder motor. The calibration movement mechanism includes an infrared detector, a controller, and a data processing module. The controller is respectively connected to the data processing module, the infrared detector, and the motion control slave computer. The data processing module can perform distance calibration, and the controller can control the infrared detector to capture infrared images according to control instructions.

[0039] In order to obtain more accurate blackbody temperature measurement results, blackbody temperature measurement is performed at different positions. The automatic adjustment device adjusts the up, down, left, and right movement of the blackbody. The movement process is as Figure 6As shown. The blackbody control lower computer adjusts the blackbody temperature through a custom serial port protocol. This serial port protocol is used to connect the blackbody control lower computer and the blackbody, and can both obtain and adjust the blackbody temperature. Common commands are as follows: Start / Stop: 10 60 00 10 00 10 91 AC / 10 60 00 10 0000 8D A0; Set temperature (0°C): 10 66 00 A0 00 00 9A 8C; Read current temperature: 10 30 00 C0 00 1044 90.

[0040] The upper computer is used for overall system control, and can send blackbody temperature verification instructions and position movement instructions to the blackbody control lower computer, as well as send distance verification instructions to the motion control lower computer. The blackbody control lower computer is used to receive the temperature verification instructions from the upper computer and adjust the blackbody temperature, or control the automatic adjustment device according to the position movement instructions to realize the up, down, left, and right position movement of the blackbody, and feedback to the upper computer that the blackbody has reached the set temperature value and position, triggering the upper computer to send a capture instruction. The motion control lower computer is used to receive the distance verification instructions from the upper computer, adjust the movement of the encoder motor of the moving mechanism, and feedback to the upper computer that the set distance has been reached.

[0041] Embodiment 2

[0042] A temperature automatic calibration method based on infrared thermal imaging technology proposed by the present invention has a process as Figure 1 shown, and the specific working process steps are as follows:

[0043] Step 1: The upper computer determines the initialized test temperature and test distance, and sends a temperature verification instruction to the blackbody control lower computer and a distance verification instruction to the motion control lower computer based on the HTTP protocol.

[0044] The temperature calibration of the present invention is carried out in an experimental environment with an ambient temperature default of 25°C. First, manually input the parameters of the temperature and distance of the initialized blackbody to the upper computer. (1) Temperature of the initialized blackbody: According to the infrared thermal imaging temperature measurement principle, usually the temperature of the highest point in the entire image is used as the temperature acquisition result. Therefore, the set test temperature of the initialized blackbody needs to exceed the indoor constant temperature. To facilitate the accurate and rapid detection of the blackbody temperature by the calibration core of the infrared thermal imaging, considering the actual temperature calibration requirements of the user, the blackbody temperature can be arbitrarily set by the user through the serial port protocol. In the present invention, the test temperature t of the initialized blackbody is set to 40°C, and the maximum value is the upper limit temperature of the blackbody as an example to set the blackbody. Adjust the blackbody temperature through the serial port protocol. (2) Distance: According to the actual temperature measurement requirements of different scenarios, usually the distance between the infrared detector and the measured object is 1 - 50 meters. Therefore, to ensure the calibration accuracy of the user's temperature measurement requirements, the distance can also be arbitrarily set by the user. The distance range for temperature measurement in the present invention is K1 - K2. During the initialization process, the closest distance is set to K1, and the farthest distance is set to K2.

[0045] The host computer sends the temperature verification instruction for initializing the test temperature to the blackbody control slave computer through the HTTP protocol, so that the main controller of the blackbody can verify whether the initial test temperature t is consistent with the current actual temperature T of the blackbody. The HTTP transmission website is set to http: / / 192.168.0.1 / report. For the convenience of reading and writing, the temperature verification instruction of the test temperature in the present invention is transmitted in the JSON file format, and the data format structure is defined as Figure 3 shown. For example: data = {id: "aq13579", type: "0", value: "40.0", timestamp: "151234456644"}, where id is a unique authentication code for an instruction, type is a flag for calibrating the instruction type, type = 0 represents that the instruction type is a blackbody temperature adjustment instruction, value is the parameter value passed by the instruction, value = 40.0 represents that the temperature parameter value passed by the instruction is 40 °C, and timestamp is a timestamp for recording the time point when the instruction is sent.

[0046] Step 2: After receiving the temperature verification instruction sent by the host computer, the blackbody control slave computer compares the current temperature T of the blackbody with the test temperature t in the temperature verification instruction, and adjusts the temperature of the blackbody to the test temperature t.

[0047] Obtain the current blackbody temperature T through the serial port protocol. The blackbody temperature verification process is as Figure 4 shown. If the current temperature T is consistent with the test temperature t, the host computer continues to send the temperature verification instruction to the motion control slave computer in JSON format through the HTTP protocol and waits for the blackbody to reach the preset temperature. If the current temperature T is inconsistent with the test temperature t, according to the test temperature set by the host computer, the blackbody control slave computer sends a control temperature to the main controller and automatically adjusts the temperature. When the current temperature T is greater than the test temperature t, the blackbody control slave computer automatically issues a cooling instruction. When the current temperature T is less than the test temperature t, the blackbody control slave computer automatically issues a heating instruction through the serial port protocol. After waiting for the blackbody to reach the test temperature t, the completion instruction is fed back to the host computer through the HTTP protocol http: / / 192.168.0.3 / perform, and the host computer sends the temperature verification instruction to the blackbody control slave computer again until the current temperature T is consistent with the test temperature t and the blackbody temperature update is completed.

[0048] Step 3: The motion control slave computer controls the coded motor to start and drive the infrared detector to move according to the verification distance instruction until the distance between the infrared detector and the blackbody reaches the test distance.

[0049] After completing a blackbody temperature adjustment, the host computer initializes the distance verification instruction and sends it to the lower-level motion control computer via the HTTP protocol, so that the lower-level motion control computer can verify whether the test distance from the blackbody is consistent with the current actual distance. The HTTP transmission URL is set to http: / / 192.168.0.2 / report. The distance verification instruction is also transmitted in the form of a JSON file. For example: data = {id: "aq02468", type: "1", value: "4.0", timestamp: "151234458899"}, where type = 1 indicates that the instruction type is a distance instruction, and value = 4.0 indicates that the distance parameter value passed by the instruction is 4 meters.

[0050] The laser rangefinder in the lower-level motion control computer is used to feedback distance information and can verify whether the current actual distance information is consistent with the test distance information sent by the host computer. After receiving the distance verification instruction sent by the host computer, the lower-level motion control computer uses the calibration movement control in the lower-level motion control computer to control the measurement distance D of the laser rangefinder. The data processing module of the calibration movement executes the distance verification instruction and compares the measurement distance D with the test distance d in the distance verification instruction sent by the host computer. The distance verification process is as Figure 5 shown. (1) If the measurement distance D is consistent with the test distance d, the lower-level motion control computer starts the encoder motor stop command and feedbacks the result to the host computer via the HTTP protocol http: / / 192.168.0.3 / perform. (2) If the measurement distance D is inconsistent with the test distance d, then according to the test distance requirement of the host computer, the lower-level motion control computer controls the trigger switch of the relay and controls the encoder motor to move according to the trigger parameter - the test distance d. When the measurement distance D is greater than the test distance d, the encoder motor automatically executes the forward instruction. When the measurement distance D is less than the test distance d, the encoder motor automatically executes the backward instruction. After the above instructions are completed, the host computer sends the distance verification instruction to the lower-level motion control computer again until the measurement D is consistent with the test distance d, and the position update of the infrared thermal imaging temperature measurement calibration device is completed, thereby realizing the temperature detection at the set test distance.

[0051] Step 4: The lower-level blackbody control computer starts the stop command and sends the current position to the host computer, triggering the host computer to send the infrared image capture instruction. The infrared detector captures the infrared image of the blackbody test temperature at the current distance, and the lower-level motion control computer uploads the captured infrared image to the host computer.

[0052] After the above steps are completed, the blackbody temperature has reached the set temperature, and at the same time, the infrared detector and the blackbody have also reached the set test distance. At this time, the lower-level motion control unit issues a stop command, stops the movement of the lower-level motion control unit, and feeds back the current position to the upper-level computer, triggering the upper-level computer to capture the infrared image of the blackbody. However, before capturing the image, in order to remove the temperature measurement deviation caused by the inconsistency of each focal plane area and ensure the accuracy of obtaining the blackbody temperature, the present invention provides a method of single blackbody spatial and time division multiplexing for capturing blackbody images. Before the upper-level computer issues a blackbody image capture command, the upper-level computer first issues motion control to the lower-level blackbody control unit. Next, the lower-level blackbody control unit will take spatial division measures and move the blackbody to the upper left corner, lower left corner, lower right corner, and upper right corner of the captured image of the 320*240 pixel matrix through program control. After one cycle of movement, the blackbody is reset. The positions where the blackbody moves are as Figure 6 shown. The present invention moves according to the actual distance corresponding to each pixel unit at preset different positions. The upper-level computer can query the database to find out how much actual distance needs to be moved at the pixel position of the current blackbody in the infrared detector. Every time the blackbody moves to one of the 4 positions of the upper left corner, upper right corner, lower left corner, or lower right corner of the captured infrared image pixel, the lower-level blackbody control unit stops moving and notifies the upper-level computer to issue a capture command. During the capture process, 6 pictures are continuously captured in a time division manner, so as to ensure that more blackbody pictures at different angles are captured at the current temperature and distance (a total of 24 pictures), and the pictures are uploaded to the upper-level system control computer. The captured infrared image of the 320*240 pixel matrix is as Figure 7 shown. In the figure, Max is the highest temperature value of the pixel temperature, Cnt is the pixel temperature value of the middle point of the picture pixel, and Min is the lowest temperature value of the pixel temperature. When the upper-level computer calculates the blackbody temperature, it obtains the current blackbody temperature by taking the average value of Max, Cnt, and Min.

[0053] Step Five: The upper-level computer performs non-uniformity correction processing on the obtained infrared image to obtain a corrected infrared image, and uses an image enhancement algorithm to perform fusion and denoising processing on the corrected infrared image.

[0054] The lower-level motion control unit uploads the captured picture to the upper-level system control computer. Next, it is necessary to obtain the temperature of the captured infrared image of the blackbody. Before this, due to the manufacturing process of the infrared detector, the photoelectric response rate of each detection pixel on the focal plane is different (the temperature value detected by the detection element on the focal plane is called the pixel value, and each focal plane has 320*240 pixel values), and there is a non-uniformity problem in the captured infrared image. Based on the gain and bias of the non-uniformity correction of the maximum and minimum blackbody temperatures, temperature correction processing is performed. The correction formula is as follows: a[i] = g[i]*n[i] + o[i], where, is the gain coefficient; is the offset; n[i] is the pixel value to be calibrated; a[i] is the calibrated pixel value; in g[i] and o[i], d represents the difference between the average value of all pixels at the maximum temperature and the average value of all pixels at the minimum temperature (for the 320*240 pixel values on the focal plane, taking the average is called the pixel average), d1 represents the difference between the pixel average at the minimum temperature and the pixel average of the object to be corrected, and d2 represents the difference between the pixel average of the object to be corrected and the average value of all pixels at the maximum temperature. h represents the average value of all pixels at the maximum temperature, l represents the average value of all pixels at the maximum temperature, n represents the average value of all pixels of the object to be corrected, and i represents the value of the pixel at the corresponding position. Among them, according to the usage experience accumulated usually, the temperature difference range of the object to be measured can be roughly known, so as to determine the maximum temperature and the minimum temperature. Use blackbody to simulate the maximum temperature and the minimum temperature respectively, and obtain the average value of the corresponding pixel data of each focal plane at the maximum and minimum temperatures through 40 simulations, so that the corrected detector can accurately present the temperature image. Since infrared thermal imaging usually uses a 14-bit processor, however, most of the current image processors on the market can only process 8-bit image data, so then the pixel values on the focal plane are linearly weighted and compressed into 8-bit data.

[0055] To ensure that the image details are enhanced and match the total dynamic range of the original infrared image background, and to ensure that in scenes with significant temperature changes, while completing the dynamic digital image compression, the details of the image are maintained as much as possible. The present invention provides an image enhancement algorithm. The processing flow of the image enhancement algorithm is as Figure 8 shown. First, the saliency of the blackbody target area M and the background B in the infrared image is classified and processed. Set the priority MG and weight MW of the blackbody target gray level to be greater than the priority BG and weight BW of the background gray level, adjust the contrast between the blackbody target and the background, and enhance the saliency of the blackbody target area. Then, the enhanced infrared image is subjected to two non-subsampled shearlet transforms (NSST), decomposed into a low-pass subband image and a band-pass subband image. The low-pass subband image contains most of the information of the blackbody target area, and the band-pass subband image contains local detail information such as the edges and textures of the infrared image. The results of the two non-subsampled shearlet transforms (NSST) are different because the enhanced contrasts are different, and the information contained in the generated images is different. One infrared image is over-enhanced and contains more information about the blackbody target area, and one infrared image is under-enhanced and contains more edge detail information. And NSST does not undergo a subsampling operation when decomposing the layers, which can effectively suppress the pseudo-Gibbs phenomenon and maintain the continuity of the image data. The low-pass subband and band-pass subband coefficients are C j0 (m,n) and C j,l (m,n), j represents the decomposition scale, l represents the decomposition direction, and (m, n) represents the position of the pixel. According to the low-pass subband fusion strategy fuse the two low-pass subband images, and according to the band-pass subband fusion strategy Fuse two band-pass sub-band images, and finally inverse transform through NSST to obtain the fused image, thus providing guarantee for accurate acquisition of blackbody temperature. After decomposing the two enhanced images through NSST, the information contained in different frequencies is different, and fusing them can effectively enhance the information volume contained in the image, thus providing guarantee for accurate acquisition of blackbody temperature. The effect of the original image is as Figure 9 , and the effect after image enhancement is as Figure 10 shown. From the comparison between Figure 9 and Figure 10 , it can be seen that the image after enhancement preserves significantly more details than the previous one, and the texture of the blackbody is clearer.

[0056] Step Six: Perform interpolation processing on each pixel in the infrared image after improving the image quality, extract the temperature values of each pixel and average them to obtain the final temperature value of the current blackbody at the test temperature and test distance.

[0057] After data compression is completed, further calculate the average value of the blackbody temperature values of the 24 collected images as the final temperature value of the current blackbody position. Record the final temperature value of the blackbody at the set test distance and test temperature in the current constant temperature environment. Further, the upper computer automatically issues a new position, which is incremented based on the previous position setting. The specific increment value can be set manually through the upper computer program. To ensure the accuracy of temperature calibration, the present invention sets the single increment value to Δk meters. After the new position is issued, the laser rangefinder in the motion control lower computer continues to feedback the current actual distance, and the laser rangefinder in the motion control lower computer judges again whether the position information matches, that is, loop to execute Steps Three, Four, and Five. When the distance set by the upper computer reaches K2 meters, the upper computer sends a reset command to the motion control lower computer, and the reset distance is the nearest distance K1 meters, completing the temperature detection at different test distances under the current blackbody test temperature. Reset means completing a cycle of temperature measurement at different distances under the current temperature, which is convenient for temperature measurement at different distances under the next temperature value. When measuring the next temperature value, it still starts from K1 meters. Further, the upper computer continues to issue a new test temperature, which is incremented based on the previous test temperature setting, and the single increment value is set to Δt °C. Next, continue to execute Steps One, Two, Three, Four, and Five until the test temperature reaches the upper limit of the blackbody temperature, that is, complete the automatic temperature detection and recording at different blackbody temperatures and different distances.

[0058] After the above steps are completed, the system controls the host computer to automatically generate a temperature measurement record table with different distances at different temperatures, and feedbacks the table to the user, thereby helping the user to achieve infrared thermal imaging temperature compensation at custom temperatures and distances, effectively replacing manual temperature detection and recording. At the same time, the automatic temperature calibration method provided by the present invention can also provide a reasonable reference for relevant calibration departments in formulating temperature calibration plans.

[0059] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An automatic temperature calibration method based on infrared thermal imaging technology, characterized in that, The steps are as follows: Step 1: Determine the initialized test temperature t and test distance d. The host computer sends a temperature verification instruction to the blackbody control slave computer according to the test temperature, and sends a distance verification instruction to the motion control slave computer according to the test distance; Step 2: After receiving the temperature verification instruction sent by the host computer, the blackbody control slave computer compares the current temperature T of the blackbody with the test temperature t in the temperature verification instruction, and adjusts the temperature of the blackbody to the test temperature t; Step 3: The motion control slave computer drives the infrared detector to move according to the distance verification instruction until the distance between the infrared detector and the blackbody reaches the test distance; Step 4: The blackbody control slave computer starts a stop command, sends the current position to the host computer, triggers the host computer to send a command to capture an infrared image. The infrared detector collects an infrared image of the test temperature of the blackbody at the current test distance, and the motion control slave computer uploads the captured infrared image to the host computer; Step 5: The host computer performs non-uniformity correction processing on the obtained infrared image to obtain a corrected infrared image, and further removes image noise to improve the image quality; The method of the non-uniformity correction process is as follows: temperature correction is performed based on the gain and bias of the non-uniformity correction for the maximum blackbody temperature and the minimum temperature, and the correction formula is as follows: , where is the gain coefficient; is the bias coefficient; is the pixel value to be calibrated; is the calibrated pixel value; in represents the difference between the mean of all pixels at the maximum temperature and the mean of all pixels at the minimum temperature, represents the difference between the mean of pixels at the minimum temperature and the mean of pixels of the object to be corrected, represents the difference between the mean of pixels of the object to be corrected and the mean of all pixels at the maximum temperature; represents the mean of all pixels at the maximum temperature, represents the mean of all pixels at the maximum temperature, represents the mean of all pixels of the object to be corrected, represents the value of the pixel at the corresponding position; knowing the temperature difference range of the object to be measured according to the accumulated usage experience usually, so as to determine the maximum temperature and the minimum temperature; Step 6: Perform interpolation processing on each pixel in the infrared image with improved image quality, extract the temperature values of each pixel and average them to obtain the final temperature value of the current blackbody at the test temperature and test distance.

2. The temperature automatic calibration method based on infrared thermal imaging technology according to claim 1, wherein The host computer is connected to the blackbody control slave computer and the motion control slave computer respectively based on the HTTP protocol; the temperature verification instruction of the test temperature is transmitted in the JSON file format, and the host computer uses the HTTP protocol to send the temperature verification instruction to the motion control slave computer in the JSON format; an image enhancement algorithm is used to denoise the corrected infrared image to improve the image quality for better visualization display of high-quality infrared images.

3. The temperature automatic calibration method based on infrared thermal imaging technology according to claim 2, wherein The JSON-format temperature verification instruction or distance verification instruction includes id, type, value, and timestamp. Among them, id is the authentication code of an instruction, type is the flag for calibrating the instruction type, type = 0 represents that the instruction type is a blackbody temperature adjustment instruction, type = 1 represents that the instruction type is a distance adjustment instruction, value is the temperature or distance parameter value passed by the instruction, and timestamp is the time stamp used to record the time point when the instruction is sent.

4. The temperature automatic calibration method based on infrared thermal imaging technology according to claim 2 or 3, characterized in that The method for the blackbody control slave computer to adjust the temperature of the blackbody in Step 2 is as follows: The blackbody control slave computer obtains the current temperature T of the blackbody through the serial port protocol. If the current temperature T is consistent with the test temperature t, go to Step 3; if the current temperature T is inconsistent with the test temperature t, the blackbody control slave computer sends a control temperature to the main controller of the blackbody to automatically adjust the temperature. When the current temperature T is greater than the test temperature t, the blackbody control slave computer automatically sends a temperature reduction instruction through the serial port protocol; when the current temperature T is less than the test temperature t, the blackbody control slave computer automatically sends a temperature increase instruction through the serial port protocol; after waiting for the blackbody to reach the test temperature t, feedback the completion instruction to the host computer through the HTTP protocol, and the host computer sends a temperature verification instruction to the blackbody control slave computer again until the current temperature T is consistent with the test temperature t.

5. The temperature automatic calibration method based on infrared thermal imaging technology according to claim 4, characterized in that, The implementation method for the motion control lower computer to drive the infrared detector to move in step three is as follows: The laser rangefinder in the motion control lower computer is used to measure the actual distance D between the infrared detector and the black body. If the actual distance D is consistent with the test distance d, the motion control lower computer issues a command to stop the encoder motor and feeds back the result to the upper computer via the HTTP protocol. If the actual distance D is inconsistent with the test distance d, the motion control lower computer controls the trigger switch of the relay and controls the movement of encoder motor II according to the test distance d. When the actual distance D is greater than the test distance d, encoder motor II automatically executes a forward command. When the actual distance D is less than the test distance d, the encoder motor automatically executes a backward command. After the distance verification command is completed, the upper computer issues another distance verification command to the motion control lower computer until the actual distance D is consistent with the test distance d.

6. The temperature automatic calibration method based on infrared thermal imaging technology according to claim 1 or 5, characterized in that In step four, the single black body spatial and time division multiplexing method is used for black body image capture. The single black body spatial and time division multiplexing method is as follows: Before the upper computer issues a capture command to the infrared detector, the upper computer issues a motion control command to the black body control lower computer. The black body control lower computer takes spatial division measures to move the black body to the upper left corner, lower left corner, lower right corner, and upper right corner of the captured image of the 320*240 pixel matrix respectively, until it moves to the upper left corner, upper right corner, lower left corner, or lower right corner of the pixel of the captured infrared image. Then the black body control lower computer stops moving and notifies the upper computer to issue a capture command. During the capture process, 6 images are continuously captured in a time division manner to ensure that black body images at different angles are captured at the current temperature and distance, and the captured images are uploaded to the upper computer. The method for moving the black body is to control the automatic adjustment device to move according to the actual distance corresponding to each pixel unit at different preset positions. The upper computer queries the actual distance that needs to be moved at the pixel position of the current black body in the infrared detector in the database. The average value of the temperature values of the black body in the 24 captured images is taken as the final temperature value of the current black body position.

7. The temperature automatic calibration method based on infrared thermal imaging technology according to claim 2, characterized in that The image enhancement algorithm is as follows: perform hierarchical processing on the saliency of the target region M and the background B of the black body in the infrared image, set the priority MG and weight MW of the gray level of the target region to be greater than the priority BG and weight BW of the gray level of the background, adjust the contrast between the black body target and the background, and enhance the saliency of the black body target region; perform two non-subsampled shearlet transforms on the enhanced infrared image, decompose it into a low-pass subband image and a band-pass subband image, and fuse the two low-pass subband images according to the low-pass subband fusion strategy and fuse the two band-pass subband images according to the band-pass subband fusion strategy Finally, the fused infrared image is reconstructed through the NSST inverse transform; where is the low-pass subband coefficient, is the band-pass subband coefficient, represents the decomposition scale, represents the decomposition direction, represents the position of the pixel, represents the fused low-pass subband coefficient, is the fused band-pass subband coefficient, 、 represent the proportion coefficients of each low-pass subband fusion when the two low-pass subbands are fused, is the low-pass subband coefficient of image I1, is the low-pass subband coefficient of image I2, is the band-pass subband coefficient of image I2, is the band-pass subband coefficient of image I1; Record the final temperature value of the black body at the currently set constant temperature environment, test distance, and test temperature. The host computer automatically issues a new verification position command. The test position is incremented by itself based on the previous test position, and the single self-increment value is set to meters. When the distance set by the host computer reaches the maximum distance K2 meters, the host computer sends a reset command to the motion control slave computer, and the reset distance is the minimum distance K1 meters, completing the temperature detection at different test distances under the current black body test temperature; the host computer continues to issue a new test temperature, and the test temperature is incremented by itself based on the previous test temperature setting, and the single self-increment value is set to , until the test temperature reaches the upper limit of the black body temperature, completing the automated temperature detection and recording at different black body temperatures and different distances.

8. A calibration device for the temperature automatic calibration method based on infrared thermal imaging technology according to any one of claims 1-7, characterized in that, It includes an upper computer, a black body control lower computer, and a motion control lower computer. The upper computer is connected to the black body control lower computer and the motion control lower computer respectively through network communication. The black body control lower computer is connected to the black body. An automatic adjustment device is provided under the black body and is connected to the black body control lower computer. The motion control lower computer is respectively connected to a calibration movement mechanism, a laser rangefinder, and a moving mechanism. The calibration movement mechanism is arranged on the upper part of the motion control lower computer. The laser rangefinder is arranged corresponding to the calibration movement mechanism vertically. The laser rangefinder is used to measure the distance between the black body and the calibration movement mechanism. The motion control lower computer is connected to the moving mechanism through a relay.

9. The temperature automatic calibration device based on infrared thermal imaging technology according to claim 8, characterized in that, The automatic adjustment device includes a horizontal sliding mechanism and a vertical lifting mechanism. The vertical lifting mechanism is slidably disposed within the horizontal sliding mechanism. Encoder motors are provided within both the horizontal sliding mechanism and the vertical lifting mechanism. The blackbody control lower computer adjusts the left - right movement of the blackbody by controlling the forward or reverse rotation of the encoder motor within the horizontal sliding mechanism, and adjusts the up - down movement of the blackbody by controlling the forward or reverse rotation of the encoder motor within the vertical lifting mechanism. An encoder motor II is provided within the moving mechanism, and the motion control lower computer adjusts the distance between the calibration movement core and the blackbody by controlling the rotation of the encoder motor II. The calibration movement core includes an infrared detector, a controller, and a data - processing module. The controller is respectively connected to the data - processing module, the infrared detector, and the motion control lower computer. The data - processing module realizes the calibration of the distance, and the controller controls the infrared detector to capture infrared images according to the control instruction. The blackbody control lower computer adjusts the blackbody temperature through a custom serial port protocol. The custom serial port protocol is used to connect the blackbody control lower computer and the blackbody, and can both acquire and adjust the blackbody temperature.

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