A method and device for obtaining the height of a target object

Abstract

The embodiments of the present application provide a method and device for acquiring the height of a target object, wherein the method for acquiring the height of a target object comprises: acquiring a spot image on the surface of the target object, wherein the spot image is obtained by making a light source emit a laser of a target frequency band to illuminate the target object and filtering with a filter of the target frequency band, and the target frequency band is selected by analyzing the spectral characteristics of the radiation of the target object; acquiring a matching object from the spot image according to the characteristics of the laser emitted by the light source, and calculating the gradient value of the matching object; acquiring the height information of the target object by searching a mapping table according to the gradient value, wherein the mapping table is obtained by calibration. Some embodiments of the present application can effectively filter out the interference of the light source radiated by the target object itself on the spot image, thereby affecting the accuracy of acquiring the height of the target object according to the spot image.

Description

Technical Field

[0001] The present application relates to the field of measurement, and specifically, embodiments of the present application relate to a method and device for acquiring target height. Background Art

[0002] In the field of height measurement of target objects (in the field of metal smelting such as steel), accurate measurement of the height of the target object (for example, the height of molten steel in a ladle) has always been a difficult point. For example, the role of measuring the liquid level in a ladle is multi-faceted: for example, in the casting process, the casting mechanism can control the opening of the ladle slide according to the molten steel level and then control the flow of molten steel injected into the ingot mold, so that the molten steel level in the mold rises steadily at the rising speed required by the mold casting process, thereby improving the quality of the ingot and preventing accidents such as splashing and overflowing steel. In addition, the temperature of the molten steel is strictly required before the casting operation. Molten steel temperature measuring equipment will be deployed on the production line to measure the temperature of the molten steel. During the measurement process, it is necessary to ensure that the rod is immersed in a precise position to obtain accurate results and avoid the rod connection mechanism from contacting the liquid surface to cause ablation. Therefore, it is objectively necessary to calculate the correct liquid level of the ladle in advance.

[0003] Based on actual factory surveys and patent paper retrieval of Baosteel and other steel companies, there are currently two main methods for measuring the liquid level of high-temperature liquid metals such as molten steel, in addition to the traditional method of workers estimating with the naked eye. One is the contact measurement method, including immersion of probes and scale rods, contact with conductive rods, etc. The other is non-contact measurement, including the use of ultrasonic, infrared rangefinders, lasers or cameras and other instruments and equipment to measure the liquid level at a distance based on various principles.

[0004] There is no need to elaborate on the shortcomings of the most common manual visual observation method. The accuracy is completely uncontrollable and extremely dependent on the experience and state of the measurement personnel.

[0005] The contact measurement method has a high calculation accuracy for the liquid level, and can achieve millimeter-level detection accuracy under optimal conditions. However, the detection medium (including probes, scale rods, conductive rods, etc.) wears out very quickly, and the servo-type mechanical structure that controls the temperature measurement medium is too close to the molten steel. After working for a long time in a high-temperature and highly polluted industrial environment, the mechanical error increases dramatically, and the maintenance cost is also very unsatisfactory. It is basically not feasible to implement in the actual production process.

[0006] The advantages of non-contact measurement methods are that they are easy to maintain and the equipment deployment is relatively economical, but they have their own defects, which makes it difficult for the measurement accuracy to meet the objective requirements: 1. There are methods that analyze and process the surface image of the ladle based on the Sobel operator, Hough transform, etc., to obtain the liquid surface contour and the outer edge contour of the ladle, and then reverse the liquid surface height based on the contour, such as Figure 1 and Figure 2As shown. The disadvantage of this method is that it relies on the integrity and smoothness of the outer contour of the ladle. However, in the actual production process, the outer contour of the ladle is irregularly deformed due to collision, wear, molten steel splashing and adhesion, which will lead to obvious contour fitting errors. The scum on the surface of the liquid surface will also seriously mislead the image fitting and measurement accuracy. 2. Ultrasonic measurement has also been widely studied and applied in the field of liquid level measurement, but the theoretical basis of ultrasonic measurement is completely based on the speed of sound. The special feature of the target liquid level of molten steel is that the temperature on the surface of the ladle will be heated by the molten steel, and the temperature rise range and range are unknown. The speed of sound is extremely sensitive to the temperature. The change of the speed of sound will cause the ultrasonic measurement results to deviate from the true value. Therefore, the ultrasonic measurement method is not suitable for the measurement requirements in this field. 3. There are also many literatures and technical studies based on laser equipment related to liquid level detection, including the camera laser combination system of laser triangulation measurement method, laser rangefinder and other equipment have long been proposed in the field of liquid level measurement. However, molten steel with a temperature of over 1500°C is itself a high radiation generator. The radiation energy of the molten steel itself will interfere with or even overwhelm the optical signal of conventional laser equipment. Therefore, laser measurement methods are severely limited under this special condition.

[0007] There are also semi-contact measurement methods such as the combination of a scale bar and a visual system, whose disadvantages are basically similar to those of contact measurement. Summary of the invention

[0008] The purpose of the embodiments of the present application is to provide a method and device for acquiring the height of a target. Some embodiments of the present application apply laser triangulation technology to special liquid height measurement, and use narrowband filtering technology to suppress the background radiation of high-radiation objects such as target objects (for example, molten steel), thereby improving the signal-to-noise ratio of the system light source signal. In some embodiments of the present application, the band selection of narrowband filtering is based on the spectral characteristic curve of specific targets such as molten steel, and the trough position with weak background light intensity is selected in a targeted manner, and the light sensitivity curve of the CCD camera is combined to comprehensively select the optimal light source band of about 400nm. Although the basic principle of some embodiments of the present application is derived from the laser triangulation method, the relative position of the light source and the camera is adjusted for the reliability and maintainability of the optical system, the optical path structure is changed from a right triangle to a non-right triangle, and the height calculation method is replaced from a triangular geometry formula to a mapping table search, which is a variant reconstruction of the classic laser triangulation method. The data in the mapping table is calibrated for sample collection with measured data, and the missing data of the collected samples are supplemented by a combination of bilinear interpolation and unilinear interpolation methods based on the measured data, thereby effectively improving the accuracy and speed of the height measurement of the target liquid level of the high-radiation light signal measured by the laser triangulation method.

[0009] In a first aspect, some embodiments of the present application provide a method for acquiring the height of a target object, the method comprising: acquiring a spot image on the surface of the target object, wherein the spot image is imaged by causing a light source to emit a laser of a target frequency band to illuminate the target object and filtering with a filter of the target frequency band, and the target frequency band is selected by analyzing the spectral characteristics of radiation radiated by the target object; acquiring a matching object from the spot image according to the characteristics of the laser emitted by the light source, and calculating a gradient value of the matching object; and acquiring the height information of the target object by searching a mapping table based on the gradient value, wherein the mapping table is acquired by calibration.

[0010] Some embodiments of the present application combine the spectral characteristics of the radiation emitted by the target object to select the target frequency band emitted by the laser light source and the filtering frequency band of the narrow-band filter before the camera imaging, which can effectively filter out the interference of the light source radiated by the target object itself on the spot image, thereby affecting the accuracy of obtaining the height of the target object based on the spot image; in addition, the embodiments of the present application adopt a table lookup method to obtain the height of the target object based on the spot image. On the one hand, it reduces the amount of calculation compared with the formula calculation method, and on the other hand, it can effectively improve the relative position of the light source and the camera (that is, improve the standard laser triangulation method described below), so as to facilitate the placement of the camera and laser light source near the target object.

[0011] In some embodiments, the target frequency band is near a balance point, wherein the balance point is determined by determining that the radiation spectrum of the target object is weak and the camera's photosensitivity reaches a set threshold.

[0012] Some embodiments of the present application can determine the characteristics of the light waves radiated by the target object and the photosensitivity characteristics of the camera to select the target frequency band, effectively overcoming the influence of the light signal radiated by the target object on the spot image, thereby affecting the height accuracy of the determined target object.

[0013] In some embodiments, the target object is molten steel, the wavelength corresponding to the target frequency band is 400 nanometers, and obtaining the spot image of the target object includes: using a blue-violet laser as a light source, and obtaining the spot image by filtering the background light wave interference generated by the molten steel with a narrow-band filter, wherein the wavelength range corresponding to the blue-violet laser is 390 nanometers to 410 nanometers, and the transmission wavelength of the narrow-band filter is 400 nanometers and the bandwidth is ±10 nanometers.

[0014] Some embodiments of the present application use a blue-violet laser with a central wavelength of 400 nanometers and a cutoff range of 390-410 nanometers as a light source, and cooperate with a narrow-band filter with a transmission wavelength of also 400 nanometers and a bandwidth of ±10 nanometers to efficiently suppress the background light wave interference generated by the molten steel itself, thereby realizing the laser triangulation measurement method for accurate measurement of the molten steel level in a high temperature and high radiation environment.

[0015] In some embodiments, the characteristic of the laser emitted by the light source is a straight line, and the matching object is a matching line segment. The matching object is obtained from the spot image according to the characteristic of the laser emitted by the light source, and the gradient value of the matching object is calculated, including: detecting the edge of the spot image to obtain a spot feature pattern; obtaining description parameters of the linear object in the spot feature pattern, and screening out at least one straight line segment; obtaining the matching line segment based on the at least one straight line segment, and calculating the gradient value of the matching line segment.

[0016] Some embodiments of the present application can further highlight the spot information of the laser line through edge detection.

[0017] In some embodiments, before detecting the edge of the light spot image and obtaining the light spot characteristic pattern, the target height acquisition method includes: performing threshold segmentation on the light spot image to remove noise on the light spot image.

[0018] Some embodiments of the present application can effectively remove noise on the spot image through threshold segmentation.

[0019] In some embodiments, the at least one straight line segment includes a plurality of straight line segments, and the obtaining of the matching line segment based on the at least one straight line segment and the calculation of the gradient value of the matching line segment include: eliminating interference line segments in the at least one straight line segment according to the slope to obtain the matching line segment.

[0020] Some embodiments of the present application effectively eliminate the influence of interfering line segments and improve the accuracy of calculating the liquid level height of the target object.

[0021] In some embodiments, the mapping table is obtained by the following calibration method: obtaining multiple gradient values ​​of the liquid surface of the target object, obtaining the liquid surface height value H of each gradient value corresponding to the multiple gradient values ​​in a contact manner, and recording each gradient value and the corresponding liquid surface height value in the mapping table.

[0022] Some embodiments of the present application use a mapping table that pre-acquires the correspondence between the gradient and the liquid level height (the height is obtained by contact), which can save the amount of calculation required to obtain the height value based on the spot image and improve the processing speed.

[0023] In some embodiments, the elements in the mapping table are completed by an interpolation algorithm.

[0024] Some embodiments of the present application can supplement the missing sample data between the maximum gradient value and the minimum gradient value within the sample range through an interpolation method.

[0025] In some embodiments, the interpolation algorithm includes at least one of a bilinear interpolation method and a single linear interpolation method, wherein the calculation formula of the single linear interpolation method is as follows:

[0026]

[0027]

[0028] Among them, Hmax corresponds to the liquid level height value mapped by the out-of-bounds maximum value Vmax, Hmin corresponds to the liquid level height value mapped by the out-of-bounds minimum value Vmin, and H1 and H2 correspond to the corresponding mapping values ​​of V1 and V2 in the calibration sample respectively.

[0029] Some embodiments of the present application use a combination of bilinear interpolation and unilinear interpolation methods to complete missing data of collected samples.

[0030] In a second aspect, some embodiments of the present application provide a device for acquiring the height of a target object, comprising: an acquisition module, configured to acquire a spot image on the surface of the target object, wherein the spot image is imaged by making a light source emit a laser of a target frequency band to irradiate the target object and filtering with a filter of the target frequency band, and the target frequency band is selected by analyzing the spectral characteristics of radiation from the target object; a matching object acquisition module, configured to acquire a matching object from the spot image according to the characteristics of the laser emitted by the light source, and calculate a gradient value of the matching object; a height information acquisition module, configured to acquire the height information of the target object by searching a mapping table based on the gradient value, wherein the mapping table is acquired by calibration.

[0031] In a third aspect, some embodiments of the present application provide a target height acquisition system, comprising: the target height acquisition device described in the second aspect above; a light source, configured to emit a laser signal of a target frequency band to the target to form a light spot on the surface of the target; a camera, configured to shoot the light spot after filtering the light signal with a narrowband filter to obtain a light spot image, and provide the light spot image to the target height measurement device.

[0032] In some embodiments, the target height measurement system further includes a fixing frame, wherein the light source and the camera are located on the fixing frame.

[0033] In a fourth aspect, some embodiments of the present application provide a computer-readable storage medium having a computer program stored thereon, and when the program is executed by a processor, the method described in the first aspect above can be implemented.

[0034] In a fifth aspect, some embodiments of the present application provide an information processing device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor can implement the method described in the first aspect when executing the program. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0036] Figure 1 This is one of the system composition diagrams of the laser triangulation method of the related art;

[0037] Figure 2 A schematic diagram of the optical principle of the laser triangulation method of the related art;

[0038] Figure 3 A flow chart of a method for obtaining the height of a target object provided in an embodiment of the present application;

[0039] Figure 4 A schematic diagram of the radiation frequency band of molten steel provided in an embodiment of the present application;

[0040] Figure 5 A light spot image taken by a camera provided in an embodiment of the present application;

[0041] Figure 6 A composition diagram of a molten steel height acquisition system provided in an embodiment of the present application;

[0042] Figure 7 A flow chart of a method for obtaining molten steel height provided in an embodiment of the present application;

[0043] Figure 8 In the embodiment of the present application, the captured spot image is filtered by the Canny operator to obtain an image with edge extraction feature information;

[0044] Fig. 9 The line segment markers are extracted after performing Hough transform on the captured image in the embodiment of the present application;

[0045] Fig.10 A schematic diagram of selecting gradient points on an image captured by an embodiment of the present application;

[0046] Fig.11 A block diagram of the target height acquisition device provided in an embodiment of the present application;

[0047] Fig.12 A schematic diagram of the composition of an information processing device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application.

[0049] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of this application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0050] Laser triangulation can achieve relatively accurate measurement results for conventional objects including solid objects and liquid surfaces at room temperature: the laser transmitter emits a light beam through a lens to form a spot pattern on the surface of the object to be measured (i.e., the target object). The camera can "see" this light spot at different angles, and the spot will be imaged on the camera's photosensitive surface. When the surface of the object to be measured changes along the optical axis, the angle of the reflected light will also change, and the image of the spot on the camera target surface will also move accordingly. The imaging position has a unique correspondence with the position of the laser axis. For a specific principle diagram, see Figure 1 and Figure 2 According to this method, the distance between the molten steel surface and the camera can be accurately measured, and the camera installation height is known information, so the height of the molten steel surface can be further deduced.

[0051] like Figure 1 As shown, the laser triangulation method of the related art includes a camera 100 and a laser 200 (ie, a laser emitter or light source), and h1, h2, and h3 in the figure represent three liquid level heights respectively. Figure 2 It can be seen that when the target liquid level rises by d, the imaging point on the sensor surface of the camera 100 also shifts by d, so the increased liquid level value can be obtained by analyzing the displacement of the imaging point. Figure 1 This is a schematic diagram of the standard laser triangulation hardware structure. The camera and light projector are rigidly connected, with the distance and angle locked. The camera shoots at an inclined angle, and the direction of the light source is perpendicular to the horizontal plane. Therefore, for planes at different heights, the angle of the light path changes when the light source is projected onto the plane and then reflected into the camera lens.

[0052] Figure 2 for Figure 1Corresponding optical principle diagram of laser triangulation measurement, the light spots projected by the light source at different horizontal heights will be reflected by the lens and will be imaged at different positions on the camera target surface. Assuming the height change of the measured plane is d, and the imaging displacement on the camera target surface after the height change is d', according to the equal angle theorem of equal sides in trigonometric geometry, it can be known that the change amplitude and direction of d are linearly related to d', so the displacement d' of the light spot on the camera target surface can be recorded by software analysis to reversely infer the target horizontal height change d. At the same time, it can also be determined that under the premise of the current fixed hardware structure, the imaging signal coordinates of the light spot at a fixed horizontal position reflected on the camera target surface are also fixed and corresponding, and the calibration method can be used to record the scale coordinates corresponding to each horizontal height in the camera target surface.

[0053] The weakness of the laser triangulation measurement technology in the related art is that it completely relies on its own laser spot imaging. For targets such as black bodies, mirror reflectors, and luminous bodies, the spot imaging pattern will be destroyed, resulting in the failure of the basic information source required to measure the target distance. For example, molten steel itself is one of the high-radiation objects. Therefore, some embodiments of the present application are based on triangulation measurement technology, and adopt spectral analysis methods and narrow-band filtering technology to implement interference light suppression, so as to overcome the shortcomings of the laser triangulation measurement technology in the related art and realize the height measurement of the molten steel liquid level.

[0054] The narrowband filter is a light-transmitting glass with a special coating treatment. It is subdivided from the bandpass filter. Its definition is the same as that of the bandpass filter, that is, this filter allows light signals to pass through in a specific band, while the light signals on both sides that deviate from this band are blocked. The passband of the narrowband filter is relatively narrow, generally less than 5% of the central wavelength value. Using a light source that matches the central wavelength of the narrowband filter can ensure that the target optical signal penetrates the filter with a slight loss while the light of other bands is cut off by the filter, thereby achieving the purpose of extracting the target light source signal (i.e., the signal corresponding to the target frequency band of the embodiment of the present application) from the strong radiation background, significantly improving the signal-to-noise ratio of the optical system.

[0055] Please see Figure 3 , Figure 3 A method for acquiring the height of a target object is provided for some embodiments of the present application, and the method for acquiring the height of a target object comprises: S101, acquiring a spot image of the surface of the target object, wherein the spot image is imaged by making a light source emit a laser of a target frequency band to illuminate the target object and filtering with a filter of the target frequency band, and the target frequency band is selected by analyzing the spectral characteristics of radiation from the target object; S102, acquiring a matching object from the spot image according to the characteristics of the laser emitted by the light source, and calculating a gradient value of the matching object; S103, acquiring the height information of the target object by searching a mapping table according to the gradient value, wherein the mapping table is acquired by calibration.

[0056] The above steps are described below as examples.

[0057] In some embodiments of the present application, the target frequency band involved in S101 is near a balance point, wherein the balance point is determined by determining that the radiation spectrum of the target object is weak and the camera's photosensitivity is good (better can be determined by determining that the photosensitivity parameter reaches a set threshold).

[0058] For example, according to the radiation spectrum data of liquid steel in the ladle collected by the spectrometer in the steelmaking workshop (such as Figure 4 ), it can be found that the red light and infrared laser equipment that are most commonly used in scientific research and commercial fields are not the most suitable light source for steelmaking scenarios, because the radiation intensity of molten steel is relatively strong in the visible light spectrum of the human eye (wavelength 400 to 760 nanometers) and the near-infrared short-wave range (near-infrared short-wave is academically defined as light waves in the range of 760 to 1100 nanometers, but the sensitivity of most industrial camera photosensitive chips to light waves above 800 nanometers drops rapidly), and the cost of light intensity suppression is relatively high. The intensity of molten steel radiation decreases rapidly from the 500 nanometer band to the ultraviolet direction (short wave), and a balance point can be achieved near the blue-violet light around 400 nanometers (i.e. the balance point), where the molten steel radiation is weak and the camera sensitivity is good. By studying the photosensitivity response curves of several common CCD cameras on the market, it can be seen that although the infrared wavelengths below 400 nanometers and above 920 nanometers are the weaker ranges in the radiation spectrum of molten steel, the light sensing ability of the camera is sharply weakened, and the current signal-to-noise ratio of the camera itself begins to increase. Ultraviolet or infrared cameras with good light sensitivity efficiency in these wavelength ranges are relatively expensive, and their economic applicability is not enough to support the implementation of production practices. Therefore, some embodiments of this application can be used as alternative solutions for academic research in reverse. 4 is a screenshot of the original interface of the spectrometer. Figure 4 The horizontal axis represents the wavelength, and the vertical axis represents the radiation intensity information corresponding to each wavelength.

[0059] As an example of the present application, when the target object is molten steel, some embodiments of the present application use a blue-violet laser with a central wavelength of 400 nanometers (i.e., the balance point) and a cutoff range of 390-410 nanometers (i.e., the corresponding target frequency band) as the light source, and cooperate with a narrow-band filter with a transmission wavelength of 400 nanometers and a bandwidth of ±10 nanometers to effectively suppress the background light wave interference generated by the molten steel itself, and realize the laser triangulation measurement method to accurately measure the molten steel level in a high-temperature and high-radiation environment. The camera required for this technical solution can be a mass-produced ordinary industrial camera. The laser light source power can be controlled within 10 watts to achieve a sufficient background light suppression effect, and clear imaging of laser lines under high-temperature molten steel above 1500°C can be achieved. The shooting effect is as follows: Figure 5The equipment selection performed according to some embodiments of the present application can achieve low hardware system deployment costs and has feasibility for application in the industrial field. The hardware structure of the measurement system (i.e., the target height acquisition system) is shown in FIG. Figure 6 shown. Figure 6 The system includes: a laser 200, whose central wavelength is 400 nanometers (i.e., the equilibrium point) and whose cutoff range is converged at 390-410 nanometers; a narrow-band filter, which is arranged in front of the camera 100, and whose wavelength is also 400 nanometers and whose bandwidth is ±10 nanometers; and the camera 100, which is configured to obtain an image of a light spot formed when the laser is irradiated onto the liquid surface of the ladle, and obtain the light spot image recorded in S101.

[0060] That is to say, in some embodiments of the present application, the target object is molten steel, the wavelength corresponding to the target frequency band is 400 nanometers, and the step of obtaining the light spot image of the target object includes: using a blue-violet laser as a light source, and obtaining the light spot image by filtering the background light wave interference generated by the molten steel with a narrow-band filter, wherein the wavelength range corresponding to the blue-violet laser is 390 nanometers to 410 nanometers, and the transmission wavelength of the narrow-band filter is 400 nanometers and the bandwidth is ±10 nanometers.

[0061] In some embodiments of the present application, the laser feature is a line (eg Figure 6 The matching object is a matching line segment, and S102 includes: detecting the edge of the light spot image to obtain a light spot feature pattern; obtaining description parameters of the linear object in the light spot feature pattern, and screening out at least one straight line segment; obtaining the matching line segment based on the at least one straight line segment, and calculating the gradient value of the matching line segment.

[0062] In order to remove noise on the spot image, in some embodiments of the present application, before performing edge detection of the spot image to obtain a spot feature pattern, S102 further includes: performing threshold segmentation on the spot image to remove noise on the spot image.

[0063] In order to eliminate the influence of redundant straight lines on matching straight lines, in some embodiments of the present application, the at least one straight line segment recorded in S102 includes multiple straight line segments, and S102 further includes: eliminating interfering line segments in the at least one straight line segment according to the slope to obtain the matching line segment.

[0064] In some embodiments of the present application, the mapping table involved in S103 is obtained by the following calibration method: obtaining multiple gradient values ​​of the liquid surface of the target object, obtaining the liquid surface height value H of each gradient value corresponding to the multiple gradient values ​​in a contact manner, and recording each gradient value and the corresponding liquid surface height value in the mapping table. For example, the elements in the mapping table are completed by an interpolation algorithm.

[0065] In some embodiments of the present application, the interpolation algorithm includes at least one of a bilinear interpolation method and a single linear interpolation method, wherein the calculation formula of the single linear interpolation method is as follows:

[0066]

[0067]

[0068] Assuming that the out-of-bounds value Vmax is greater than the existing sample range, then set V1 and V2 to be the maximum and second largest values ​​in the existing samples; assuming that the out-of-bounds value Vmin is less than the existing sample range, then set V1 and V2 to be the minimum and second smallest values ​​in the existing samples.

[0069] The target is molten steel, and combined with Figure 6 as well as Figure 7 The example illustrates the process of obtaining the target height.

[0070] Figure 6 The following is a diagram showing the composition of the hardware system corresponding to the target height acquisition method in some embodiments of the present application. Figure 6 It can be seen that the optical design of the embodiment of the present application is similar to the standard laser triangulation system (such as Figure 1 or Figure 2 As shown in the figure, there are the following differences: In the standard laser triangulation system ( Figure 1 and Figure 2 ), the position of the laser 200 should be perpendicular to the horizontal plane, that is, the liquid surface. If the laser 200 is installed at an oblique angle, the camera 100 should be set to be placed perpendicular to the measured plane, because the triangle in the classical triangulation theory should be a right triangle to satisfy the height calculation formula. However, the optical system in some embodiments of the present application is installed and fixed on a steel frame platform. It is difficult to vertically suspend the laser 200 and maintain the relative position stability of the entire optical system in engineering deployment. At the same time, the floating range of the ladle liquid level is small, and the estimation accuracy requirement can be relaxed to the centimeter level. Therefore, Figure 6 The camera 100 and the laser 200 of some embodiments of the present application are respectively deployed at high places on both sides of the steel frame platform to aim at the central ladle relatively. The related technology requires the step of converting the spot pixel position into the liquid level height through trigonometric formulas, which is also replaced by a mapping table method in the embodiments of the present application.

[0071] The camera 100 of some embodiments of the present application obtains the image by using the laser triangulation principle and narrow-band filtering technology. Figure 5 After the molten steel image is obtained, the software algorithm (i.e., the target height acquisition method of some embodiments of the present application) is used to analyze and process the image. The full process steps of the target height acquisition method are as follows:

[0072] S401, Take a picture, that is, the camera 100 of Figure 6 takes a picture of the upper surface of the ladle, obtains the spot image, and sends it to the image processing module (for executing the method for obtaining the height of the target object).

[0073] S402, Threshold segmentation, that is, perform threshold segmentation on the obtained spot image to clean up the low-gray noise data. According to the optical scheme design of some embodiments of the present application, it is necessary to extract that the laser spot has been highlighted as high-brightness pixels by the system hardware. Therefore, the area with lower gray level must be texture noise. Set the threshold as T. For any pixel G(x, y) on the spot image, x and y are the horizontal and vertical axis coordinates of the spot picture respectively, and G is the gray value of this pixel point. If G(x, y) < T, then G(x, y) = 0. The setting of the threshold T can be manually set, or the gray values of all pixels in the whole picture can be statistically analyzed by an adaptive method and then arranged from the largest to the smallest, and the gray value with the 7% order is taken as the value of T.

[0074] S403, Edge detection. In order to further highlight the laser line spot information, use the Canny operator to perform edge detection operation on the image after threshold segmentation. The Canny operator is one of the edge detection operators widely used in the field of image processing and can be directly called and executed through the OpenCV third-party open source tool library. Figure 5 After being filtered by the Canny operator, the output is as Figure 8 shown. Figure 8 This is the intermediate result display after the Canny operator processing, which characterizes the edge extraction feature information.

[0075] S404, Line detection. The light source of the laser used in some embodiments of the present application is the one-dimensional line laser most commonly used in laser triangulation. Therefore, the spot object to be extracted is a straight line segment. Perform Hough transformation on the Figure 8 edge retrieval result map, obtain the description parameters of all linear objects in the image, then screen out the straight line segment results, and finally mark the line segments and draw them on the original Figure 5 as the result shown in Fig. 9 The Hough transformation is also one of the classic image processing algorithms and can also be directly loaded and called through tool libraries such as OpenCV.

[0076] S405, Slope screening. Assume Fig. 9After the straight line search shown in the figure, two lines are detected. Since the relative installation positions of the camera and the laser light source are known, the laser irradiation angle and the light spot imaging angle are also known, the interfering line segments can be eliminated based on the slope. For example, the elimination method includes: assuming that the endpoints of the line segment are A (Xa, Ya) and B (Xb, Yb) (the coordinate values ​​of the endpoints are obtained during the Hough transform process), then the slope L = (Xa-Xb) / (Ya-Yb), after comparing the difference between the slopes of all line segments and the expected slope value of the light spot, select the line segment with the closest slope and eliminate other results.

[0077] S406, gradient calculation. After the spot matching line segment is determined in S405, the process of calculating its gradient value V includes: assuming the image height is MH, traversing all pixel points of the spot line, taking the horizontal coordinates X1, X2, X3, X4, and X5 of the five points whose vertical coordinates are MH / 2, MH / 2+20, MH / 2+40, MH / 2+60, and MH / 2+80 respectively, and calculating the gradient value V=X1+X2+X3+X4+X5, Fig.10 The five marked bright spots are the gradient sampling points generated by the intersection of the five sampling axes and the spot line segments.

[0078] S407, determine that the mapping table has been calibrated. The mapping table has been calibrated, which means that a calibration mapping table of the light spot coordinates and the ladle liquid level Height needs to be established according to the pixel gradient value V. The calibration method of S408 may include: S4081, data sampling, that is, deploying a fixed hardware system (such as the hardware system of the embodiment of the present application) in the workshop Figure 6 As shown in the figure, the ladle liquid level gradient value V is obtained, and the precise liquid level height value H is obtained by contact means such as a scale measuring rod, and the mapping relationship of V–>H is recorded in the mapping table; and S4082, the mapping table is completed. For example, after collecting more than 100 mapping samples, it is necessary to perform bilinear interpolation to complete the missing samples within the measured sample range, that is, between the maximum gradient value Vmax and the minimum gradient value Vmin, to ensure that the corresponding liquid level height H value can be found in the mapping table for each pixel value change of the gradient V.

[0079] For example, the specific filling method and algorithm are as follows:

[0080] V refers to the ladle liquid level gradient value obtained by the laser triangulation method provided in the embodiment of the present application during the calibration sampling process, and H refers to the precise liquid level height value obtained by contact methods such as a scale measuring rod in the calibration sample. For each gradient sampling value, there is a corresponding liquid level height value recorded in the mapping table with a mapping relationship of V–>H. Therefore, in the following formula, Hmax corresponds to the liquid level height value mapped to the out-of-bounds maximum value Vmax, Hmin corresponds to the liquid level height value mapped to the out-of-bounds minimum value Vmin, and H1 and H2 correspond to the corresponding mapping values ​​of V1 and V2 in the calibration sample, respectively, which are obtained by the measurement practice method during the calibration process.

[0081] The execution method of bilinear interpolation completion is: suppose the mapping table gradients are V1, V2, V3, V4, and V5 from small to large, where V3 is the data missing sample not recorded in the mapping table, and the others are the existing recorded samples and the corresponding H mapping values. Then the calculation formula of H3 corresponding to V3 is:

[0082]

[0083] After H3 is calculated, it is entered into the mapping table together with V3. The sample range in the mapping table completed by interpolation calculation should have covered the liquid level in most cases. However, in the actual production process, there may occasionally be a maximum or minimum value outside the existing sample range in the mapping table. In this case, the new extreme value is calculated by single linear interpolation and entered into the mapping table to expand the sample range of the mapping table. Assuming that the out-of-bounds value Vmax is greater than the existing sample range, then V1 and V2 are set as the maximum and second largest values ​​in the existing samples, and the single linear interpolation formula for calculating Hmax is:

[0084]

[0085] Assume that the out-of-bounds value Vmin is smaller than the existing sample range, then set V1 and V2 as the minimum and second minimum values ​​of the existing samples, and the single linear interpolation formula for calculating Hmin is:

[0086]

[0087] S409, height conversion. That is, after the mapping table is constructed, the currently measured liquid level H is directly calculated according to the gradient value V obtained in S406.

[0088] Please refer to Fig.11 , Figure 4 It is shown that the embodiment of the present application provides a device for obtaining the height of a target object. It should be understood that the device is similar to the above Figure 3Corresponding to the method embodiment, the various steps involved in the above method embodiment can be executed. The specific functions of the device can be referred to the description above. To avoid repetition, detailed description is appropriately omitted here. The device includes at least one software function module that can be stored in a memory in the form of software or firmware or solidified in the operating system of the device. The target height acquisition device includes: an acquisition module 101, configured to acquire a spot image on the surface of the target object, wherein the spot image is obtained by making a light source emit a laser of a target frequency band to irradiate the target object and using a filter of the target frequency band to filter and image, and the target frequency band is selected by analyzing the spectral characteristics of the radiation of the target object; a matching object acquisition module 102, configured to acquire a matching object from the spot image according to the characteristics of the laser emitted by the light source, and calculate the gradient value of the matching object; a height information acquisition module 103, configured to acquire the height information of the target object by searching a mapping table according to the gradient value, wherein the mapping table is acquired by calibration.

[0089] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the above-described device can refer to the aforementioned Figure 3 The corresponding process in the method will not be described in detail here.

[0090] Some embodiments of the present application provide a target height acquisition system, the target height acquisition system comprising: Figure 4 A target height acquisition device (for example, the target height acquisition device can be set on a server); a light source (such as Figure 6 The laser 200 is configured to emit a laser signal of a target frequency band to the target object to form a light spot on the surface of the target object; a camera (such as Figure 6 The camera 100 is configured to shoot the light spot after filtering the light signal with a narrow-band filter to obtain a light spot image, and provide the light spot image to the target height measurement device.

[0091] In some embodiments, the target height measurement system further includes a fixed frame (eg, a steel frame), wherein the light source and the camera are located on the fixed frame.

[0092] Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the system described above can refer to the aforementioned Figure 3 or Figure 6 The corresponding process in the method will not be described in detail here.

[0093] Some embodiments of the present application provide a computer-readable storage medium having a computer program stored thereon, which can implement the above-mentioned Figure 3 or Figure 7 The method described.

[0094] like Fig.12 As shown, some embodiments of the present application provide an information processing device 500, including a memory 510, a processor 520, and a computer program stored in the memory 510 and executable on the processor 520, wherein the processor 520 reads the program through a bus 530 and executes the program to implement the above Figure 3 or Figure 7 The method described.

[0095] Processor 520 can process digital signals and can include various computing structures, such as complex instruction set computer structure, reduced instruction set computer structure, or a structure that implements a combination of multiple instruction sets. In some examples, processor 520 can be a microprocessor.

[0096] The memory 510 may be used to store instructions executed by the processor 520 or data related to the execution of instructions. These instructions and / or data may include code to implement some or all functions of one or more modules described in the embodiments of the present application. The processor 520 of the present disclosure embodiment may be used to execute the instructions in the memory 510 to implement Figure 3 The memory 510 includes a dynamic random access memory, a static random access memory, a flash memory, an optical memory or other memory known to those skilled in the art.

[0097] In several embodiments provided in the present application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely schematic. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architecture, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present application. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a part of a code, and the module, a program segment or a part of a code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or action, or can be implemented with a combination of dedicated hardware and computer instructions.

[0098] In addition, the functional modules in the various embodiments of the present application may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.

[0099] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium, including several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0100] The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0101] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0102] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

Claims

1. A method for obtaining the height of a target object, characterized in that: The target object height acquisition method comprises: Acquire a spot image on the surface of the target object, wherein the spot image is obtained by causing a light source to emit a laser of a target frequency band to illuminate the target object and filtering the target object with a filter of the target frequency band, and the target frequency band is selected by analyzing the spectral characteristics of the radiation of the target object; Acquire a matching object from the light spot image according to the characteristics of the laser emitted by the light source, and calculate a gradient value of the matching object; Acquire the height information of the target object by searching a mapping table according to the gradient value, wherein the mapping table is acquired by calibration; The feature of the laser emitted by the light source is a line, the matching object is a matching line segment, and the matching object is obtained from the spot image according to the feature of the laser emitted by the light source, and the gradient value of the matching object is calculated, including: Detecting the edge of the light spot image to obtain a light spot characteristic pattern; Acquire description parameters of the linear object in the light spot characteristic pattern, and select at least one straight line segment; Acquire the matching line segment based on the at least one straight line segment, and calculate the gradient value of the matching line segment; The at least one straight line segment includes a plurality of straight line segments, and the obtaining of the matching line segment based on the at least one straight line segment and the calculation of the gradient value of the matching line segment include: excluding interference line segments in the at least one straight line segment according to the slope to obtain the matching line segment.

2. The target height acquisition method according to claim 1, characterized in that: The target frequency band is near a balance point, wherein the balance point is determined by determining that the radiation spectrum of the target object is weak and the camera's photosensitivity reaches a set threshold.

3. The target height acquisition method according to claim 1, characterized in that: The target object is molten steel, the wavelength corresponding to the target frequency band is 400 nanometers, and the step of acquiring the spot image of the target object includes: The light spot image is obtained by using a blue-violet laser as a light source and cooperating with a narrow-band filter to filter the background light wave interference generated by the molten steel, wherein the wavelength range corresponding to the blue-violet laser is 390 nanometers to 410 nanometers, and the transmission wavelength of the narrow-band filter is 400 nanometers and the bandwidth is ±10 nanometers.

4. The target height acquisition method according to claim 1, characterized in that: Before detecting the edge of the light spot image and obtaining the light spot characteristic pattern, the target height acquisition method includes: Threshold segmentation is performed on the light spot image to remove noise on the light spot image.

5. The target height acquisition method according to claim 1, characterized in that: The mapping table is obtained by the following calibration method: Acquire multiple gradient values ​​of the liquid surface of the target object, acquire the liquid surface height value H of each gradient value corresponding to the multiple gradient values ​​in a contact manner, and record each gradient value and the corresponding liquid surface height value in the mapping table.

6. The target height acquisition method according to claim 5, characterized in that: The elements in the mapping table are completed by an interpolation algorithm.

7. The method for acquiring the height of a target object as claimed in claim 6, characterized in that: The interpolation algorithm includes at least one of a bilinear interpolation method and a unilinear interpolation method. The calculation formula of the single linear interpolation method is as follows: Among them, Hmax corresponds to the liquid level height value mapped by the out-of-bounds maximum value Vmax, Hmin corresponds to the liquid level height value mapped by the out-of-bounds minimum value Vmin, and H1 and H2 correspond to the corresponding mapping values ​​of V1 and V2 in the calibration sample respectively.

8. A device for obtaining the height of a target object, characterized in that: The target height acquisition device comprises: An acquisition module is configured to acquire a spot image on the surface of a target object, wherein the spot image is obtained by causing a light source to emit a laser of a target frequency band to illuminate the target object and filtering the target object with a filter of the target frequency band, and the target frequency band is selected by analyzing the spectral characteristics of radiation from the target object; a matching object acquisition module, configured to acquire a matching object from the light spot image according to the characteristics of the laser emitted by the light source, and calculate a gradient value of the matching object; a height information acquisition module, configured to acquire the height information of the target object by searching a mapping table according to the gradient value, wherein the mapping table is acquired by calibration; The characteristic of the laser emitted by the light source is a line, the matching object is a matching line segment, and the matching object acquisition module is specifically configured as follows: Detecting the edge of the light spot image to obtain a light spot characteristic pattern; Acquire description parameters of the linear object in the light spot characteristic pattern, and select at least one straight line segment; Acquire the matching line segment based on the at least one straight line segment, and calculate the gradient value of the matching line segment; The at least one straight line segment includes a plurality of straight line segments, and the matching object acquisition module is specifically configured to: eliminate interference segments in the at least one straight line segment according to the slope to obtain the matching segment.

9. A target height acquisition system, characterized in that: The target height acquisition system comprises: The target height acquisition device as claimed in claim 8; A light source is configured to emit a laser signal of a target frequency band toward the target object to form a light spot on the surface of the target object; The camera is configured to shoot the light spot after filtering the light signal with narrow-band filtering to obtain a light spot image, and provide the light spot image to the target height acquisition device.

10. The target height acquisition system according to claim 9, characterized in that: The target height acquisition system further comprises a fixing frame, wherein the light source and the camera are located on the fixing frame.

11. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method described in any one of claims 1 to 7 can be implemented.

12. An information processing device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the method described in any one of claims 1 to 7 can be implemented.

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