Dynamic arc adaptive temperature field measuring device and measuring method

Abstract

The invention discloses a self-adaptive temperature field measuring device and method for a dynamic arc. The device comprises an arc generating mechanism, an image collecting device, a reflecting mirror set, an angle reference component and a processing unit. The angle reference component is installed on the arc generation mechanism, the central axis is coaxial with the geometric installation axis of the arc generation mechanism, and an angle scale structure is arranged on the surface and used for establishing the mapping relation between the pixel position and the observation angle. The reflector group is arranged on the side of the arc generation mechanism and is used for reflecting radiation light from different directions of the dynamic arc to the same image acquisition device so as to realize multi-view imaging; the processing unit determines the projection angle of each visual angle in real time in the dynamic discharge process, performs tomography reconstruction based on multi-visual-angle radiation information, obtains emission coefficient distribution of an arc section, adaptively distinguishes a high-temperature region from a low-temperature region according to isoline topological characteristics, performs temperature mapping, and realizes accurate reconstruction of a dynamic arc temperature field. And the stability and reliability of measurement under the dynamic working condition are improved.

Description

Technical Field

[0001] This invention relates to dynamic arc temperature field measurement, and more particularly to an adaptive temperature field measurement device and method for dynamic arcs. Background Technology

[0002] Dynamic electric arcs are widely present in high-power discharges, plasma processing, and power equipment operation. Their temperature field distribution directly affects discharge stability, energy transfer efficiency, and equipment safety. Therefore, accurate measurement of the temperature field of dynamic electric arcs is of great significance. Existing technologies for measuring the temperature field of electric arcs mainly include optical imaging measurements based on fixed arrangements of multiple cameras or multiple viewpoints, and tomographic reconstruction methods combining spectral information. These methods typically rely on predetermined observation angles, fixed optical path structures, or static models to complete temperature field inversion. However, in practical applications, dynamic electric arcs often exhibit position drift, morphological changes, and oscillations during discharge, causing the effective projection angles at different viewpoints to change over time. The assumption of fixed angles is difficult to hold in the long term, leading to deviations between the reconstructed model and the actual physical state. Furthermore, existing methods often focus on mapping the emission intensity as a whole using a single threshold or empirical parameter, making it difficult to adaptively distinguish between high-temperature and low-temperature regions based on the radiation characteristics of different areas within the arc, thus affecting the accuracy and stability of the temperature inversion results. The aforementioned problems mean that existing technologies generally suffer from insufficient adaptability to changes in operating conditions, limited reconstruction accuracy, and poor consistency of temperature field timing when measuring dynamic electric arcs, thus restricting their application effectiveness in complex dynamic discharge environments. Summary of the Invention

[0003] Purpose of the invention: The purpose of this invention is to provide an adaptive temperature field measurement device for dynamic arcs that can achieve multi-view adaptive calibration, real-time angle determination, and is suitable for temperature field reconstruction during dynamic arc discharge; on the other hand, it provides an adaptive temperature field measurement method for dynamic arcs.

[0004] Technical Solution: The adaptive temperature field measuring device for dynamic electric arcs of the present invention includes an arc generating mechanism for generating dynamic electric arcs, an image acquisition device, and a reflector group; it also includes an angle reference component and a processing unit electrically connected to the image acquisition device; the angle reference component is movably mounted on the arc generating mechanism, and its central axis is coaxial with the geometric mounting axis of the arc generating mechanism; the surface of the angle reference component has an angle scale structure that can be recognized by the image acquisition device and used to determine angle information; the reflector group is disposed on the side of the arc generating mechanism and is used to reflect radiation light from different directions of the dynamic electric arc to the image acquisition device.

[0005] Preferably, the geometric mounting axis of the arc generating mechanism is not used to characterize the instantaneous physical axis of the dynamic arc during the discharge process, but rather serves as a predetermined spatial reference axis for establishing a stable observation coordinate system during the calibration phase.

[0006] Preferably, the angle reference component is a cylinder, and the angle scale structure is a circumferential scale engraved on its cylindrical sidewall.

[0007] Preferably, the angle reference component is a metal cylinder, the diameter and height of which are set so that it can be completely imaged by the image acquisition device without obstructing the main radiation area of ​​the electric arc; the angle scale is set circumferentially along the side wall of the cylinder, covering the complete angle range, and the scale interval and scale accuracy meet the resolution requirements of the projection angle calibration.

[0008] Preferably, it further includes a support mechanism, which is fixedly installed on the arc generating mechanism, and the angle reference component is rotatably installed on the support mechanism so that the angle reference component can move into or out of the imaging field of view of the image acquisition device and can rotate on the support mechanism along the axis of the angle reference component.

[0009] Preferably, the reflector group includes at least five planar reflectors, each with a different mirror surface normal direction, and each mirror surface is positioned facing the discharge area of ​​the arc generating mechanism.

[0010] Preferably, the reflector group is designed to allow radiation from different spatial directions of the dynamic electric arc to be reflected and simultaneously enter the imaging plane of the same image acquisition device, thereby forming multiple electric arc field-of-view sub-images corresponding to different projection angles in a single frame image.

[0011] Preferably, the device further includes an optical imaging unit disposed between the mirror group and the image acquisition device. The optical imaging unit includes at least a narrowband filter, the center wavelength of which corresponds to a characteristic atomic spectral line of the dynamic electric arc.

[0012] Preferably, the processing unit is an industrial control computer or an embedded processor.

[0013] An adaptive temperature field measurement method for dynamic electric arcs based on the above-mentioned device includes the following:

[0014] Without igniting the dynamic electric arc, the angle reference component is moved into the imaging field of view, and the angle scale images of the angle reference component under at least five different viewing angles are synchronously acquired by the reflector group and the image acquisition device as calibration images. After completion, the angle reference component is moved out of the imaging field of view.

[0015] Based on the calibration image, the processing unit identifies the angle scale structure of the angle reference component and establishes a mapping relationship between the pixel coordinates of the calibration image and the corresponding observation angle by fitting.

[0016] The dynamic electric arc is ignited, and the single-spectral radiation projection images of the dynamic electric arc are simultaneously acquired from at least five different viewing angles by the reflector group and the image acquisition device.

[0017] For the multi-view images acquired at each moment, the brightness centroid position of the electric arc in each single-view sub-image is extracted, and the real-time projection angle corresponding to each single-view sub-image at that moment is determined according to the mapping relationship.

[0018] Using the real-time projection angle as input, the projection data of each single-view sub-image at the corresponding time are reconstructed by tomography to obtain the two-dimensional emission coefficient distribution of the arc cross section at that time.

[0019] The two-dimensional emission coefficient distributions of multiple cross sections are combined along the arc axis to form a three-dimensional emission coefficient field of the arc.

[0020] Contour topology analysis is performed on the three-dimensional emission coefficient field or its layer-by-layer two-dimensional cross-section. High-temperature and low-temperature regions are adaptively identified according to preset rules, and the emission coefficients are mapped to temperature using corresponding functional relationships to generate the three-dimensional temperature field of the electric arc at that moment, or the temperature field distribution that changes with time.

[0021] Preferably, the preset rule for distinguishing between high-temperature and low-temperature regions is as follows: in the normalized emission coefficient distribution map, the closed contour line where the maximum emission coefficient is located is taken as the reference boundary; within the reference boundary, if there is an independent region completely surrounded by a closed contour line with a higher value, then the independent region is determined to be a high-temperature region, and the remaining regions within the reference boundary and the regions outside the boundary are determined to be low-temperature regions.

[0022] Preferably, the closed contour line where the emission coefficient reaches its maximum value is the only closed contour line where the emission coefficient reaches its global maximum value, and the value corresponding to this contour line can be used as the threshold for adaptive discrimination.

[0023] Preferably, the step of mapping the emission coefficient to temperature using corresponding functional relationships means that: for the determined high-temperature region, a nonlinear enhancement function that is more sensitive to changes in the emission coefficient is used for temperature calculation; for the determined low-temperature region, a smooth mapping function based on the overall distribution characteristics is used for temperature calculation to suppress the influence of noise.

[0024] Preferably, the extraction of the image feature position of the electric arc in each single-view sub-image is as follows: after establishing the mapping relationship between the pixel coordinates of the calibration image and the corresponding observation angle, the mapping relationship remains unchanged in the subsequent dynamic electric arc measurement process.

[0025] Preferably, the tomographic reconstruction employs an iterative algorithm, which is either the Simultaneous Algebraic Reconstruction Technique (ART) or the Maximum Likelihood Expectation Maximization (MLEM) algorithm.

[0026] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: By introducing an angle reference component that can be recognized by the image acquisition device into the arc generating mechanism, and combining it with a reflector group to achieve multi-view radiation information acquisition under the same image acquisition device, an imaging structure that can complete multi-view measurement without the need for multiple cameras to synchronize is formed; at the same time, the correspondence between pixel position and observation angle is established by using calibration images, and the projection angle of each view is determined in real time during dynamic discharge. The two-dimensional emission coefficient distribution of the arc cross section is obtained by combining tomographic reconstruction method. On this basis, the high temperature zone and the low temperature zone are adaptively distinguished according to the topological characteristics of contour lines and mapped to temperature respectively, realizing the accurate reconstruction of the dynamic arc temperature field. This not only improves the angle matching accuracy of multi-view measurement under dynamic working conditions, but also solves the problem of temperature inversion error accumulation caused by fixed observation angle and rough regional division in the prior art, significantly improving the stability and reliability of dynamic arc temperature field measurement. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the calibration state of the device of the present invention;

[0028] Figure 2 This is a schematic diagram of the measurement state of the device of the present invention;

[0029] Figure 3 This is a schematic diagram of the angle reference component and support mechanism of the present invention;

[0030] Figure 4 Here is an example diagram of the emission coefficient measured in this invention;

[0031] Figure 5 This is an example diagram of the temperature field measured by the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be further described below with reference to the accompanying drawings.

[0033] like Figures 1-5 As shown, this embodiment provides an adaptive temperature field measurement device for dynamic electric arcs and a measurement method based on the device, which is used to illustrate the specific implementation of the present invention for multi-view adaptive calibration and temperature field reconstruction under dynamic discharge conditions.

[0034] like Figures 1-3As shown, the dynamic arc adaptive temperature field measuring device of this embodiment includes an arc generating mechanism 1, an angle reference component 3, a support mechanism 4, a reflector group 5, an optical imaging unit 6, an image acquisition device 7, and a processing unit 2. The arc generating mechanism 1 includes a welding torch at the top and a water-cooled copper plate as the counter electrode. The welding torch is fixedly installed above the water-cooled copper plate, forming a discharge space for generating a dynamic arc. The axis of the welding torch is substantially perpendicular to the surface of the water-cooled copper plate. The angle reference component 3 is movably installed on the arc generating mechanism 1, and its central axis is coaxial with the geometric installation axis of the arc generating mechanism 1. This geometric installation axis is not used to characterize the instantaneous physical axis of the dynamic arc during the discharge process, but rather serves as a pre-determined spatial reference axis for establishing a stable observation coordinate system during the calibration phase. The angle reference component 3 is a metal cylinder with an angle scale structure engraved circumferentially on its sidewalls, covering a range of 0°-360°. The angle reference component 3 is a stainless steel cylinder with a diameter of 20mm-40mm and a height of 50mm-100mm. The angle scale interval is 6°, and the angle calibration accuracy is better than ±0.2°. The above-mentioned size setting allows it to be completely imaged by the image acquisition device 7 and used for angle calibration without significantly obstructing the main radiation area of ​​the electric arc.

[0035] The support mechanism 4 is used to support the angle reference component 3. The support mechanism 4 is fixedly installed on the water-cooled copper plate of the arc generating mechanism 1. The angle reference component 3 is rotated and movably installed on the support mechanism 4 on the water-cooled copper plate, so that the operator can manually place (move in) or remove (move out) the angle reference component 3 along its axis into (moves in) or from the imaging field of view of the image acquisition device 7, and can manually rotate and fine adjust it around its own axis.

[0036] In this embodiment, the support mechanism 4 is an adjustable bracket sleeve, which is fixedly installed on the water-cooled copper plate or its supporting base of the arc generating mechanism 1. This fixed installation is detachable, allowing the support mechanism 4 to be moved out of the imaging field of view as a whole after calibration. The adjustable bracket sleeve houses and supports the precision angle measuring column 3. The precision angle reference component 3, the angle measuring column, can be manually inserted or removed along the axial direction of the bracket sleeve, and can be manually rotated around its central axis by the operator within the sleeve. The water-cooled copper plate has cooling water channels machined inside, and is equipped with a cooling water inlet and outlet. Forced water cooling is achieved through an external water pump and circulation pipeline. The device is powered by an external AC power grid and is electrically connected to the processing unit 2, the image acquisition device 7, and the water pump via a power cord.

[0037] During the system calibration phase, the operator manually inserts the angle reference component 3 along the axis of the support mechanism 4 into the imaging field of view of the image acquisition device 7, and calibrates the imaging plane of the image acquisition device using the angle scale structure set on its side wall. This is equivalent to pre-determining a fixed coordinate origin and angle reference in space. After calibration, the operator removes the angle reference component 3 and its corresponding support mechanism 4 from the arc generating mechanism 1 and moves them out of the imaging field of view of the image acquisition device 7, ensuring that neither is located in the optical imaging path during the measurement phase, thus avoiding obstruction and interference with the dynamic arc radiation. Subsequently, during the ignition of the dynamic arc and the occurrence of oscillation, deflection, or shape changes, the arc axis is no longer assumed to remain constant. Instead, the actual observation angle corresponding to each projection viewpoint is determined in real time by analyzing the relative position changes of the arc image in this fixed coordinate system, thereby achieving accurate measurement of the dynamic arc temperature field.

[0038] The reflector group 5 is located to the side of the arc generating mechanism 1 and includes at least five plane reflectors. The normal directions of the mirror surfaces of each plane reflector are different, and all are oriented towards the discharge area of ​​the arc generating mechanism 1. Each plane reflector is mounted on a rigid support frame via an adjustable mirror mount. During initial installation, with the assistance of a laser collimator or theodolite, the mirror mounts are adjusted to converge the reflected light paths to the entrance pupil of the image acquisition device 7, ensuring that each viewpoint sub-image is clear and separated on the imaging plane. After adjustment, the mirror mount fixing screws are tightened. Through the reflector group 5, the radiation light from different spatial directions of the dynamic arc is reflected and simultaneously enters the imaging plane of the same image acquisition device 7, thereby forming multiple arc field-of-view sub-images corresponding to different projection angles in a single frame image. The optical imaging unit 6 is located between the reflector group 5 and the image acquisition device 7 and includes an imaging lens, a neutral density filter, and a narrowband filter. The center wavelength of the narrowband filter corresponds to a characteristic atomic spectral line of the dynamic electric arc, such as the Ar I 696.5 nm spectral line, with a bandwidth of 10 nm. It is used to filter out the radiation of the electric arc at this single characteristic spectral line and suppress the continuous spectral background. The image acquisition device 7 is a high-speed camera connected to the optical imaging unit 6, used to acquire single-spectral-line radiation projection images of the dynamic electric arc at a preset frame rate. In this embodiment, the camera frame rate can be set to 1000 frames / second, with a resolution of, for example, 1280×720 pixels, and it is connected to the subsequent processing unit via a high-speed data interface. The processing unit 2 is an industrial control computer (ICC) electrically connected to the image acquisition device 7. The ICC of the processing unit 2 contains an image batch processing module, an emission coefficient field tomography reconstruction module, and a temperature field calculation and analysis module (e.g., developed based on MATLAB or Python), used to control the image acquisition process and perform all calculations.

[0039] In this embodiment, the reflector group 5 includes at least five planar reflectors. This number is based on relevant literature and analysis of existing technologies, representing the minimum amount of support data required for multi-view tomographic reconstruction. By pre-designing the mirror normal direction of each reflector, five field-of-view sub-maps with different projection angles can be formed in a single frame image, achieving the minimum support requirement for multi-view projection angles.

[0040] Processing unit 2 is used to perform angle scale recognition processing on the calibration image. The processing method includes: preprocessing the calibration image to enhance the scale structure features, and automatically extracting the position parameters of the scale lines in the image based on the regular distribution characteristics of the scale lines on the sidewall of the angle reference component 3; on this basis, using the projection position of the axis center of the angle reference component 3 in the image as the angle calculation reference, converting the spatial position relationship of any pixel point in the image relative to the reference into the corresponding projection angle value, thereby establishing a mapping relationship between image pixel coordinates and actual projection angles. Scale line extraction and angle mapping can be implemented using conventional image processing and geometric calculation methods in the field. Specifically, the arc brightness distribution in each single-view sub-image can be analyzed, the centroid coordinates of the arc brightness distribution at the corresponding time can be calculated, and the centroid coordinates can be substituted into a pre-established mapping function between pixel coordinates and observation angles to obtain the real-time projection angles of the dynamic arc in each field-of-view sub-image across multiple frames; the specific algorithm form is not limited.

[0041] In terms of program logic, processing unit 2 executes multiple functional modules sequentially according to a preset process order. These modules call each other sequentially and pass results based on data dependencies. During the calibration phase, after establishing the angle mapping function, the calibration image processing module outputs a "calibration complete" status message to the system control module. Upon receiving this status message, the system control module enters the measurement preparation state and stops calling calibration-related image processing flows, retaining only the image acquisition and data processing logic corresponding to the measurement flow.

[0042] In the measurement preparation state, the operator must move the angle reference component 3 along with the support mechanism 4 out of the imaging field of view of the image acquisition device 7, ensuring it is not located in the optical imaging path. Once the condition that the angle reference component 3 is not within the imaging field of view is met, the processing unit 2 begins processing the subsequently acquired image data according to the measurement procedure, thereby achieving the process switch from the calibration stage to the measurement stage. This process switch is completed through the cooperation of the program control logic of the processing unit 2 and manual operation.

[0043] In this embodiment, each planar mirror in the mirror assembly 5 is fixedly mounted on the same support frame via a mirror mount, and the relative positional relationship between the mirrors remains fixed after installation. The mirror surface of each mirror faces the discharge area of ​​the arc generating mechanism 1, and its mirror normal direction is preset so that the arc radiation light reflected by each mirror forms a field of view sub-map corresponding to different projection angles, and is imaged separately on the imaging plane of the image acquisition device 7.

[0044] Based on the above-described device, the dynamic arc adaptive temperature field measurement method of this embodiment includes the following steps:

[0045] The dynamic arc adaptive temperature field measuring device of this embodiment sequentially goes through a calibration state and a measurement state during operation. In the calibration state, the angle reference component 3 is manually moved into the imaging field of view of the image acquisition device 7, and each reflector of the reflector group 5 is fixed. The reflector group 5 and the image acquisition device 7 synchronously acquire angle scale images of the angle reference component 3 from five (or more) different viewing angles, which are used as calibration images. Based on the calibration images, the processing unit 2 identifies the angle scale structure of the angle reference component 3 and establishes a mapping function between the pixel coordinates of the calibration image and the corresponding observation angle by fitting. After the calibration is completed and the angle mapping function is established, the angle reference component 3 and the support mechanism 4 are manually moved out of the imaging field of view and locked, and the device switches to the measurement state.

[0046] During measurement, the angle reference component 3 and the support mechanism 4 are not within the imaging field of view. The arc generating mechanism 1 continuously generates a dynamic arc. The reflector group 5, the optical imaging unit 6, and the image acquisition device 7 work together to continuously acquire multi-view radiation image sequences of the dynamic arc. During measurement, the processing unit 2 continuously runs the image processing, angle calculation, tomographic reconstruction, and temperature inversion processes until the measurement task is completed.

[0047] To ensure measurement accuracy, the relative positions of the reflector group 5, optical imaging unit 6, and image acquisition device 7 are fixed and installed on a rigid support or a platform with vibration isolation function to ensure the stability of the imaging optical path throughout the entire process from calibration to measurement.

[0048] Step 1: System calibration and angle mapping establishment:

[0049] With the electric arc ignited, the angle reference component 3 is positioned within the imaging field of view of the image acquisition device 7 using the support mechanism 4. The axial position of the angle reference component 3 is aligned with the geometric mounting axis of the arc generating mechanism 1 as a reference. The image acquisition device 7 is activated, and the angle reference component 3 is observed from five (or more) angles via the reflector group 5. A clear calibration image containing the angle reference component 3 and its scale is acquired using a relatively long exposure time (e.g., 30,000 μs). Upon completion, the angle reference component 3 and the support mechanism 4 are immediately removed from the field of view to avoid interfering with subsequent arc measurements.

[0050] Processing unit 2 performs preprocessing on the calibration image, including grayscale conversion and filtering for noise reduction. It then uses an image recognition algorithm to automatically extract the contour and angle scale lines of the angle reference component 3. Through geometric relationship calculation or function fitting, it establishes an angle mapping function between the coordinates of each pixel on the image plane and the actual spatial angle value, achieving pixel-level precision angle calibration.

[0051] Step 2: Acquisition of dynamic arc multi-view image sequence:

[0052] An optical imaging unit 6 is mounted in front of the lens of an image acquisition device 7. A dynamic electric arc (potentially an oscillating or deflecting arc) between the welding torch and the water-cooled copper plate is ignited. A high-speed camera 7 is set to perform high-speed continuous imaging with a short exposure time (e.g., 100 μs). Radiation from different directions of the dynamic arc is reflected by the mirror group 5 and passes through the optical imaging unit 6, forming five (or more) arc sub-images from different perspectives on a single frame image of the high-speed camera in the image acquisition device 7. This allows for the continuous acquisition of a multi-view, single-spectral-line (696.5 nm) arc radiation image sequence.

[0053] Step 3: Real-time projection angle is automatically determined:

[0054] For each captured image frame, processing unit 2 first performs image segmentation to obtain sub-images corresponding to each viewpoint. Each sub-image undergoes preprocessing such as background subtraction, noise suppression, and intensity normalization. Subsequently, the centroid coordinates of the arc brightness distribution in each sub-image are calculated; the centroid represents the principal projection direction of the arc radiation at that viewpoint. Substituting these centroid coordinates into the angle mapping function established in step one allows for the real-time calculation of the precise projection angle corresponding to each viewpoint sub-image in that frame. Since the arc is dynamic, the centroid position differs between frames, therefore the calculated projection angle also varies with time (frame order).

[0055] The angle mapping function is a deterministic functional relationship established during the calibration process in step one. It is used to map pixel positions in the image coordinate system to the corresponding actual spatial projection angles. During the measurement process, processing unit 2 independently calculates the centroid of each viewpoint sub-image for each frame of the acquired image, and substitutes the obtained centroid coordinates into the angle mapping function to obtain the projection angle value corresponding to that frame of the image. The above calculation process is repeated for each frame of the image to achieve continuous updating of the projection angle over time.

[0056] Step 4: Emission coefficient field tomography reconstruction:

[0057] The tomographic reconstruction module of processing unit 2 receives the real-time projection angle and corresponding sub-image projection data of each frame. The grid size of the reconstruction section is set to M×M, preferably 100×100 in this embodiment. In this embodiment, the reconstruction of the emission coefficient field is achieved using an iterative tomographic reconstruction method. After obtaining the multi-view projection angle and projection intensity data at the corresponding moment, processing unit 2 iteratively updates the emission coefficient distribution based on a preset spatial grid, gradually approximating the actual collected projection data with the projection result calculated from the current emission coefficient distribution, until the preset convergence condition is met. The iterative reconstruction method can be implemented using synchronous algebraic reconstruction technology (ART), maximum likelihood expectation-maximization algorithm (MLEM), or other equivalent algebraic tomographic reconstruction algorithms. The specific iteration form and parameter settings can be adjusted according to application requirements. Using the projection data of the current frame, the two-dimensional emission coefficient distribution of the arc section at that moment is solved on the set grid. To obtain three-dimensional information, multiple sections can be selected at fixed intervals along the arc axis, the above two-dimensional reconstruction process can be repeated, and all two-dimensional distribution data can be stacked to form a three-dimensional emission coefficient field. Figure 4 Here is an example diagram of the yOz section of the obtained three-dimensional emission coefficient field.

[0058] Step 5: Adaptive discrimination and temperature field calculation in high and low temperature regions:

[0059] The reconstructed (normalized) emission coefficient field is analyzed layer by layer (two-dimensional cross-section) or as a whole (three-dimensional volume data). Contour lines of the emission coefficient field are calculated. The adaptive discrimination rule is as follows: First, a unique closed contour line is found where the emission coefficient reaches its global maximum value, and this is used as the baseline boundary. Then, within the region enclosed by this baseline boundary, it is searched to see if there exists an independent region completely surrounded by a closed contour line with a higher value (e.g., 0.9). If such a region exists, it is determined to be a high-temperature region; a minimum connected area threshold can be set when determining a high-temperature region to exclude noise spikes; the remaining regions within the baseline boundary and the regions outside the boundary are determined to be low-temperature regions. Contour line extraction can be implemented based on a two-dimensional matrix interpolation algorithm or a digital contour extraction method; the above adaptive discrimination rule is executed by the processing unit 2 through program logic, and its implementation can be accomplished using conventional image or matrix analysis methods in this field, with no specific limitation on the implementation method.

[0060] Finally, temperature mapping is performed based on the standard temperature method to determine the relationship between the relative magnitude of the emission coefficient and temperature. For the emission coefficient characteristics of different temperature regions, a piecewise fitting model is used for temperature mapping to improve inversion accuracy and physical plausibility: for the high-temperature region, a nonlinear enhancement function sensitive to changes in the emission coefficient (e.g., [missing information]) is selected. Where ε represents the normalized emission coefficient value at the current pixel or voxel position, This represents the temperature value mapped from the emission coefficient ε within the high-temperature region (core region) of the electric arc. The constant term in the function is an example value; its specific value is calculated by performing the aforementioned measurement and reconstruction process on a standard plasma source with a known temperature (such as a standard-temperature electric arc or blackbody furnace), and fitting and calibrating the reconstructed emission coefficient with the standard temperature to highlight the high-temperature gradient of the arc core. For the low-temperature region, a smooth mapping function based on the overall distribution characteristics (e.g., ...) is selected. Where ε represents the normalized emission coefficient value at the current pixel or voxel position, This represents the temperature value corresponding to the emission coefficient ε within the low-temperature region. The constant term in the function is an example value; its specific value is obtained by performing the aforementioned measurement and reconstruction process on a standard plasma source with a known temperature (such as a standard-temperature electric arc or blackbody furnace), and then fitting and calibrating the reconstructed emission coefficient with the standard temperature. This generates a two-dimensional temperature field of the arc cross-section at that moment, or stacks it into a three-dimensional temperature field. Figure 5 Here is an example diagram of the yOz cross section of the obtained temperature field.

[0061] The calibration process for the temperature mapping function is an offline process performed once or periodically. Its procedure is completely consistent with the actual measurement process, except that the dynamic arc is replaced by a standard plasma radiation source or blackbody radiation source with a known temperature. By performing the same image acquisition, angle determination, and emission coefficient reconstruction process as in steps three and four on this standard radiation source, the corresponding emission coefficient value is obtained, and a correspondence is established between this value and the known standard temperature, thus obtaining the mapping parameters for subsequent measurements. After this calibration process is completed, the obtained parameters are directly used in the online measurement stage and do not need to be repeated during the measurement process.

[0062] Step Six: Full-Time Temperature Field Evolution Analysis:

[0063] Repeat steps three through five for the entire image sequence acquired by the high-speed camera. This will allow you to obtain the spatial distribution and temporal evolution of the temperature field throughout the entire process of the dynamic electric arc from ignition to extinction, achieving true dynamic online measurement.

[0064] When the measurement task is completed or needs to be terminated, the processing unit 2 stops the trigger signal of the image acquisition device 7, the high-speed camera ends continuous acquisition, and the arc generating mechanism 1 stops discharging. The system returns to the non-working state, and if necessary, the angle reference component 3 and the support mechanism 4 can be moved back into the imaging field of view to re-execute the calibration process.

[0065] This embodiment solves the problem of real-time calibration of dynamic arc projection angle by using a movable precision angle reference component 3. Based on single-spectral-line tomography reconstruction, it innovatively distinguishes high and low temperature regions and performs differentiated temperature inversion according to the contour topology of the emission coefficient field, thereby realizing high-precision and high-robust measurement of dynamic and asymmetric arc temperature field.

Claims

1. An adaptive temperature field measuring device for a dynamic electric arc, comprising an arc generating mechanism (1) for generating a dynamic electric arc, an image acquisition device (7), and a reflector assembly (5); characterized in that, It also includes an angle reference component (3) and a processing unit (2) electrically connected to the image acquisition device (7); the angle reference component (3) is movably mounted on the arc generating mechanism (1), and its central axis is coaxial with the geometric mounting axis of the arc generating mechanism (1); the surface of the angle reference component (3) has an angle scale structure that can be identified and the angle information determined by the image acquisition device (7); the reflector group (5) is disposed on the side of the arc generating mechanism (1) and is used to reflect the radiation light from different directions of the dynamic arc to the image acquisition device (7).

2. The adaptive temperature field measuring device according to claim 1, characterized in that, The angle reference component (3) is a cylinder, and the angle scale structure is a circumferential scale engraved on its cylindrical sidewall.

3. The adaptive temperature field measuring device according to claim 1, characterized in that, It also includes a support mechanism (4), which is fixedly installed on the arc generating mechanism (1), and the angle reference component (3) is rotatably installed on the support mechanism (4).

4. The adaptive temperature field measuring device according to claim 1, characterized in that, The reflector group (5) includes at least five planar reflectors, each with a different mirror surface normal direction, and each mirror surface is positioned facing the discharge area of ​​the arc generating mechanism (1).

5. The adaptive temperature field measuring device according to claim 1, characterized in that, The device further includes an optical imaging unit (6), which is located between the mirror group (5) and the image acquisition device (7). The optical imaging unit (6) includes at least a narrowband filter, the center wavelength of which corresponds to a characteristic atomic spectral line of the dynamic arc.

6. The adaptive temperature field measuring device according to claim 1, characterized in that, The processing unit (2) is an industrial control computer or an embedded processor.

7. An adaptive temperature field measurement method for a dynamic electric arc based on the device described in any one of claims 1-6, characterized in that, Includes the following: Without igniting the dynamic electric arc, the angle reference component (3) is moved into the imaging field of view, and the angle scale images of the angle reference component (3) at at least five different viewing angles are synchronously acquired by the reflector group (5) and the image acquisition device (7) as calibration images. After completion, the angle reference component (3) is moved out of the imaging field of view. Based on the calibration image, the processing unit (2) identifies the angle scale structure of the angle reference component (3) and establishes the mapping relationship between the pixel coordinates of the calibration image and the corresponding observation angle by fitting. The dynamic electric arc is ignited, and the single-spectral radiation projection images of the dynamic electric arc at at least five different viewing angles are synchronously acquired by the reflector group (5) and the image acquisition device (7). For the multi-view images acquired at each moment, the brightness centroid position of the electric arc in each single-view sub-image is extracted, and the real-time projection angle corresponding to each single-view sub-image at that moment is determined according to the mapping relationship. Using the real-time projection angle as input, the projection data of each single-view sub-image at the corresponding time are reconstructed by tomography to obtain the two-dimensional emission coefficient distribution of the arc cross section at that time. The two-dimensional emission coefficient distributions of multiple cross sections are combined along the arc axis to form a three-dimensional emission coefficient field of the arc. Contour topology analysis is performed on the three-dimensional emission coefficient field or its layer-by-layer two-dimensional cross-section. High-temperature and low-temperature regions are adaptively identified according to preset rules, and the emission coefficients are mapped to temperature using corresponding functional relationships to generate the three-dimensional temperature field of the electric arc at that moment, or the temperature field distribution that changes with time.

8. The adaptive temperature field measurement method according to claim 7, characterized in that, The preset rule for distinguishing between high-temperature and low-temperature regions is as follows: In the normalized emission coefficient distribution map, the closed contour line where the maximum emission coefficient is located is taken as the reference boundary; within the reference boundary, if there is an independent region completely surrounded by a closed contour line with a higher value, then the independent region is determined to be a high-temperature region, and the remaining regions within the reference boundary and the regions outside the boundary are determined to be low-temperature regions.

9. The adaptive temperature field measurement method according to claim 7, characterized in that, After establishing the mapping relationship between the pixel coordinates of the calibration image and the corresponding observation angle, the mapping relationship remains unchanged during subsequent dynamic arc measurement.

10. The adaptive temperature field measurement method according to claim 7, characterized in that, The tomographic reconstruction employs an iterative algorithm, which may be either a synchronous algebraic reconstruction technique or a maximum likelihood expectation maximization algorithm.

Images