Patent Application
20230051041
The invention relates to a system and a method for determination and of a modification of a 3D information of a metallurgical vessel. In particular, the invention relates to a system and a method for determination of a surface reconstruction of a metallurgical vessel and allows to determine a modification such as the refractory wear of such a vessel, subsequent to a certain usage.
A metallurgical vessel generally comprises a refractory lining inside a steel shell. The refractory lining acts as a thermal insulation and it protects the steel shell, e.g. during treatment and transport of a hot molten metal inside the metallurgical vessel. During a step of treatment or transport, typically the refractory lining wears. This wear results in a modified surface of the refractory lining in an inner part (inside) a metallurgical vessel. Systems for measuring the wear of a refractory lining are disclosed in EP 2 558 816 B1 where a laser scanner is used for obtaining a contour of a lining. A measurement system using a stereo-matrix-camera on a manipulator is disclosed in WO 03/081157 A1.
The inventors have realized, that obtaining a 3D information, like a reconstruction of the (especially inner) surface of a metallurgical vessel is highly desirable. Generally, such 3D information of a metallurgical vessel can be useful for many applications, such as determination of the wear, or in determination of a residual wall thickness, etc. These values are important for the security of the use of a metallurgical vessel. For a reliable determination e.g. for security reasons such as preventing break outs, based on the obtained 3D information, this 3D information must show a high precisions and reproducibility. Therefore, laser scanners cannot provide such a high precision in a comparable time, as with such scanners all points must be measured subsequently, which leads to increasing measurement times when increasing the number of measured points. The present invention allows for a reproducible and fast determination of a very high amount of measurements points. Especially, the present invention makes it possible, to obtain a 3D information of a large inner part (or even the whole inner part) of a metallurgical vessel at a high precision and in short time.
Therefore, it is an object of the invention to provide a system and a method for determination of a 3D information or a modification of a metallurgical vessel, whereas the 3D information or modification can be obtained repeatably in a short period of time, and whereas the 3D information or modification is of high precision. In a further object, the 3D information or the modification can contain a high number of measurement points. It is a further object of the invention to provide a system and method allowing the determination of security relevant factors for the use of a metallurgical vessel.
The object is achieved by a method for determination of a 3D information of an inner part of a metallurgical vessel according to claim 1.
The object is achieved by a method for determination of a modification of a 3D information of an inner part of a metallurgical vessel according to claim 2.
The object is achieved by an imaging system for determination of a modification or of a 3D information of an inner part of a metallurgical vessel according to claim 9. The object is achieved by a data processing device for determination of a 3D information of an inner part of a metallurgical vessel according to claim 12.
The object is achieved by a data processing device for determination of a modification of an inner part of a metallurgical vessel according to claim 13.
The object is achieved by a system for determination of a modification or of a 3D information of an inner part of a metallurgical vessel according to claim 14.
The core idea of the invention is to provide at least two optical images of a metallurgical vessel from different imaging device positions outside of the metallurgical vessel, and to calculate a 3D information or a modification of the metallurgical vessel. In a first embodiment of the invention, the object is achieved by providing a method for determination of a 3D information, especially of a point cloud or of a 3D surface reconstruction or of a 3D object, of an inner part of a metallurgical vessel comprising the steps of:
In a second embodiment of the invention, the object is achieved by providing a method for determination of a modification of an inner part of a metallurgical vessel, comprising the steps of:
In a third embodiment of the invention, the object is achieved by providing an imaging system for determination of a modification or of a 3D information, especially of a point cloud or of a 3D surface reconstruction or of a 3D object, of an inner part of a metallurgical vessel comprising:
In a fourth embodiment of the invention, the object is achieved by providing a data processing device for determination of a 3D information, especially of a point cloud or of a 3D surface reconstruction or of a 3D object, of an inner part of a metallurgical vessel (50) programmed to:
In a fifth embodiment of the invention, the object is achieved by providing a data processing device for determination of a modification of an inner part of a metallurgical vessel programmed to:
In a sixth embodiment, the object is achieved by providing a system for determination of a modification or of a 3D information, especially of a point cloud or of a 3D surface reconstruction or of a 3D object, of an inner part of a metallurgical vessel comprising:
In an alternative sixth embodiment of the invention, the object is achieved by providing a system for determination of a 3D information, especially of a point cloud or of a 3D surface reconstruction or of a 3D object, of an inner part of a metallurgical vessel comprising:
In an alternative seventh embodiment of the invention, the object is achieved by providing a system for determination of a modification of an inner part of a metallurgical vessel comprising:
In the first and second embodiments, in a first step, providing of a metallurgical vessel is performed. The metallurgical vessel is preferably one of: a steel ladle, a basic oxygen furnace, an electric arc furnace, an AOD converter (Argon-Oxygen-Decarburization). The subsequent steps are preferably computer implemented steps, thus these steps may be triggered or executed by a program code implemented on a computer.
Capturing of a first optical image of at least one first inner part of the metallurgical vessel, from a first imaging device position outside of the metallurgical vessel, with a first optical axis is done by a first imaging device, e.g. by a first digital camera. Capturing of a second optical image of at least one second inner part of the metallurgical vessel, from a second imaging device position outside of the metallurgical vessel, with a second optical axis is done by a second imaging device, e.g. by a second digital camera.
Capturing is to be understood to cause an imaging device to provide an optical image. Capturing can be performed by sending a signal instruction to an imaging device to trigger capturing of an optical image, and further receiving the optical image at a computer, e.g. receiving such optical images at a data processing device, such as in the third or fourth embodiment. Capturing can also be performed by selecting a certain optical image from a (e.g. constant) stream of optical images provided by an imaging device, such as a video camera, and further receiving the optical image at a computer, e.g. receiving such optical images at a data processing device, such as in the third or fourth embodiment.
An imaging device is to be understood as an electronic appliance for acquisition of optically detectable points, generally comprising an optical system (such as a lens) and a sensor (e.g. CCD or CMOS sensor) and an electronic circuit. Preferably, the imaging devices (such as the first and the second imaging devices) are digital cameras.
Preferably, the imaging device positions (such as the first and second imaging device positions) are outside of the metallurgical vessel. The inventors have found, that the positioning of the imaging devices outside the metallurgical vessel has several advantages, such as allowing for a larger angle of view, thereby allowing for a larger surface section to be imaged and therefore also a larger area where the 3D information or modification can be determined per imaging device used. Also positioning the imaging device outside of the metallurgical vessel has shown to largely increase the lifetime of the imaging device, as the harsh environment inside the metallurgical vessel often forces replacement due to failures in the lens or the camera electronics, even in the case where the imaging device is actively cooled.
A 3D information may comprise a point cloud, a 3D surface reconstruction or a 3D object.
Preferably, the 3D information comprises a point cloud. A point cloud (or: 3D point cloud) preferably comprises a set of n 3D coordinates of points relating to a respective surface, that is points Pi = Pi(xi, yi, zi), where i=1..n. Such a point cloud can have the form of a table (e.g. with values in columns for each number of point: i, xi, yi, zi). Preferably, the 3D information comprises at least a set of 1 million entries, more preferably at least 5 million entries, such as a point cloud comprising at least 1 million 3D coordinates of points of a respective surface (n ≥ 1.000.000) and more preferably at least 5 million 3D coordinates of points of a respective surface (n ≥ 5.000.000).
Preferably, the 3D information comprises a 3D surface reconstruction. A 3D surface reconstruction may comprise a polygon mesh, connecting a set of 3D coordinates of points of a respective surface (that is points of the point cloud). Preferably, the 3D information comprises a 3D object. A 3D object may comprise a closed 3D surface reconstruction.
Calculating a 3D point cloud of at least one inner part of the metallurgical vessel from at least the first optical image and the second optical image determines a set of 3D coordinates of points of a surface of an inner part of the metallurgical vessel. The calculation can be done using state of the art methods, such as e.g. stereo matching or a multi view stereo algorithm using multi view matching. Generally, depth information can be calculated by triangulation between corresponding image points between different images. Calculation of a 3D surface reconstruction or a 3D object can be done using e.g. the coordinates of the points of the point cloud and applying a mesh onto these points.
In the first embodiment, preferably storing the 3D information of the at least one inner part of the metallurgical vessel, may be performed on a remote (network) drive in the form of a data structure, such as a computer-readable file on a computer readable medium (in the memory, or on a local or remote disk, or alike). The 3D information may additionally comprise other values, such as an intensity value, a colour code including the colour of a certain pixel, or a material code including a material information (e.g. which material is detected at a certain point Pi with index i, such as e.g. a metal, or a refractory material). The stored 3D information may be kept for later evaluation, e.g. for the comparison in the second embodiment. The stored 3D information could be a point cloud, or a 3D surface reconstruction, or a 3D object, at a timestep t=t0. In case of a point cloud it could be represented by points Pi (t)= Pi(xi, yi, zi) at a timestep t=t0.
In the second and fifth embodiment, determining a modification of the metallurgical vessel based on the comparison of the calculated 3D information (e.g. the actually calculated 3D information may be comprising a point cloud of Pi (t1)= Pi(xi, yi, zi) at a timestep t=t1) with a previously stored 3D information (e.g. Pi (t0) at a timestep t=t0) of the metallurgical vessel can e.g. be done by generating a displacement map between the previously stored 3D information with the actually calculated 3D information (e.g. Pi (t1)- Pi (t0)). In case the 3D point clouds at different time steps (Pi (t1) and Pi (t0)) do not comprise the same xi, yi, zi values, interpolation or averages taking into account the information from the nearest neighbouring points is used in the comparison. Also, comparison might be done between the calculated 3D information in the form of a 3D surface reconstruction or a 3D object (at timestep t=t1) with a previously stored 3D information in the form of a 3D surface reconstruction or a 3D object (at a timestep of t=t0). The determined differences (e.g. Pi (t1)- Pi (t0); or taking into account the information from nearest neighbouring points, or from a 3D surface reconstruction or 3D object) can show the amount of wear between the refractory lining or it can also show any clogging of e.g. a metal sticking onto the refractory lining.
Generating an output based on the determined modification of a metallurgical vessel can be done by a certain signal (e.g. warning signal) relating to the modification or by means of any other signal, e.g. used to start a specific action.
The output could e.g. be used to trigger a repair of the lining in a certain part of the vessel. The output could be used to trigger an oxygen lance to burn away clogged metal, or alike. The output signal can also be stored to document process stability or even process security levels.
The metallurgical vessel is preferably one of: a steel ladle, a basic oxygen furnace, an electric arc furnace, an AOD converter (Argon-Oxygen-Decarburization).
Preferably a local material information can be determined due to the difference in emission spectra yielding different colours or intensities in the captured images. Preferably the material information can contain information on the position of a refractory material, a metallic material, or alike. Preferably the material information is overlaid to the output image. Preferably the 3D information further comprises the material information.
Preferably, the generated output comprises the material information together with the calculated 3D information. Preferably the output is used to generate an alarm signal. Such an alarm signal may be provided e.g. in the case that a specific target is reached, such as e.g. a wear is above a certain threshold. Preferably, the generated output comprises wear information together with the calculated 3D information, such as e.g. a color coded 3D information, the color determining the amount of wear (e.g. red in regions of high wear, and blue in regions of low wear).
Preferably, the at least one first inner part of the metallurgical vessel in the first optical image and the at least one second inner part of the metallurgical vessel in the second optical image overlap, preferably the region of overlap relative to the total image content of the first optical image and the second optical image is at least 50%, more preferably, the overlap is at least 70%.
Preferably, the steps of capturing optical images, such as capturing the first and the second optical image, is done within 1000 milliseconds, preferably within 500 milliseconds, more preferably within 250 milliseconds, by a first and a second imaging device, which are synchronized. Initial experiments have shown that this reduces motion blur, but also any blur induced due to different thermal properties (as the metallurgical vessel is cooling down). For very hot surfaces it was found that especially capturing all images within 500 milliseconds is preferable, as the effect of heat haze otherwise leads to disturbances.
Preferably, the first optical image is captured from a first fixed (non-moveable) imaging device position with a first fixed optical axis and whereas the second optical image is captured from a second fixed (non-moveable) imaging device position with a second fixed optical axis. Preferably, the first imaging device for capturing a first optical image is mounted at a first fixed imaging device position with a first fixed optical axis and whereas the second imaging device for capturing a second optical image is mounted at a second fixed imaging device position with a second fixed optical axis. A fixed imaging device position and a fixed optical axis can be achieved by mounting the optical imaging devices at a fixed position, e.g. to a rigid frame connected to the floor. A fixed imaging device position is understood to be a non-moveable imaging device position. A fixed optical axis is understood to be a non-moveable fixed imaging position. Thus, it is preferred that none of the imaging device positions and none of the optical axis can be moved, such as e.g. obtained, when the optical imaging device is connected to a (moving) manipulator or an arm of a robot. Thus it is preferable that none of the imaging devices (such as the first imaging device and the second imaging device) is mounted on a moveable manipulator or on a moveable arm of a robot. A fixed imaging device position and a fixed optical axis gives the advantage of a steady and high-quality camera calibration (in the sense that the imaging device position is very well defined in terms of x, y, z coordinates, and in terms of its optical axis). The inventors have found, that such a high-quality camera calibration is preferable for high quality 3D reconstructions of a metallurgical vessel.
Preferably, capturing a first optical image is done by a calibrated first imaging device and capturing a second optical image is done by a calibrated second optical imaging device. Preferably, all imaging devices are calibrated before capturing an optical image. Calibration of an imaging device is done by a process called camera calibration (sometimes also referred to as camera resectioning) which relates to determining several parameters, such as intrinsic or extrinsic parameters, of the imaging device. These parameters can e.g. be represented in a matrix (e.g. 3×4 camera matrix). Intrinsic parameters can comprise the focal length, scale factors, the principal point, the image sensor format, lens distortion parameters and others. Extrinsic parameters include parameters relating to the coordinate system transformation from 3D parameters of the scene (“world coordinates”) to 3D imaging device coordinates. These parameters define (and depend on) the imaging device position and to the optical axis. For non-fixed imaging device, a calibration is possible. The inventors have found out, that in case of a fixed imaging device, the calibration yields improved results, especially over a longer period of time.
Preferably, the first optical imaging device is mounted on a fixed position, preferably on a frame connected to the floor. Preferably, the second optical imaging device is mounted on a fixed position, preferably on a frame connected to the floor. Preferably, all imaging devices are mounted on a fixed position, preferably on a frame connected to the floor. Preferably, the imaging system comprises a frame.
Preferably, the first optical axis and the second optical axis define directions, whereas the angle (α) between these directions is smaller than 20°, preferably smaller than 10°. The first optical axis and the second optical axis can be parallel lines (defining an angle between its directions of a=0°). Also, they can be skewed lines (non-intersecting, non-parallel lines), or they can be intersecting lines.
Preferably, the distance of the first imaging device position and the second imaging device position is in the range of 0.5 m to 4 m, preferably between 1 m and 3 m. These ranges have proven to give a high precision result.
Preferably, the minimum distance from the metallurgical vessel to the nearest imaging device is in the range of 3 m to 30 m, more preferably 5 m to 20 m. These ranges have proven to give a high precision result, while also the camera position is far enough away from the hot metallurgical vessel.
The inventors have found that preferably, the ratio between the distance of the first imaging device position and the second imaging device position to the distance from the metallurgical vessel to its nearest imaging device position is in the range of 0.01 to 1.4, preferably between 0.05 to 0.6. These ratios have shown to yield high quality images of large parts of the metallurgical vessel, especially in regions which can be covered or uneven, e.g. due to depositions of metal or slag, in order to reduce areas which are otherwise not easily visible from the outside.
Preferably, the determined modification comprises at least one of: An amount of wear of the lining, a minimum residual wall thickness, an image of a residual wall thickness, an image of regions where the residual wall thickness lies within a predefined range, an alarm in case the residual wall thickness lies within a predefined range.
Preferably, the first and second imaging devices for capturing optical images are digital optical cameras, capable of capturing optical images with more than 1.5 Megapixels, more preferably of more than 8 Megapixels. These resolutions have shown to give a high precision result. These resolutions can be reached by e.g. FullHD cameras or 4 K cameras.
Generally, capturing of images is performed on a metallurgical vessel in the hot state, e.g. at a temperature of more than 700-800° C. of the surface of the refractory lining. Therefore, preferably the first and second image devices for capturing optical images are suitable for capturing images of a metallurgical vessel in the hot state. Preferably the imaging devices (such as the first, second and third imaging devices) can comprise heat shields (e.g. by a metallic housing). Preferably the imaging devices (such as the first, second and third imaging devices) can comprise active cooling systems, comprising e.g. liquid (e.g. water) or gaseous (e.g. air or nitrogen) cooling media.
Preferably, capturing of the first and second optical images of the first and second inner parts of the metallurgical vessel is done when the metallurgical vessel is in a rest place. Preferably, the metallurgical vessel is a ladle. When the metallurgical vessel is a ladle, preferably capturing of the first and second optical images of the first and second inner parts of the ladle is done when the ladle is at the ladle repair place.
In the first and second embodiments, additional steps of capturing further optical images of at least further inner parts of the metallurgical vessel from a further imaging device position, with a further optical axis, by a further imaging device are preferable. Preferably, the first and second embodiments comprise the additional steps of capturing a third optical image of at least one third inner part of the metallurgical vessel, from a third imaging device position outside the metallurgical vessel, with a third optical axis, by a third imaging device, and more preferably additionally comprises capturing a fourth optical image of at least one fourth inner part of the metallurgical vessel, from a fourth imaging device position outside the metallurgical vessel, with a fourth optical axis, by a fourth imaging device. In the third and the alternative sixth and alternative seventh embodiments further imaging devices for capturing further optical images of at least further inner parts of the metallurgical vessel from further imaging device positions outside the metallurgical vessel, with a further optical axis, are preferably comprised. Preferably, the third and alternative sixth and alternative seventh embodiment further comprises a third imaging device for capturing a third optical image of at least one third inner part of the metallurgical vessel, from a third imaging device position outside the metallurgical vessel, with a third optical axis, and more preferably additionally comprises a fourth imaging device for capturing a fourth optical image of at least one fourth inner part of the metallurgical vessel, from a fourth imaging device position outside the metallurgical vessel. Such additional imaging devices and additional captured optical images enhance the angle of view / the area captured by the imaging devices and overall lead to 3D surface reconstructions / comparisons of larger inner parts; thus, they increase the area for the reconstruction inside the metallurgical vessel.
Preferably, the data processing device is understood to mean one or more devices for carrying out the respective method steps described above, and which, for this purpose, comprise either discrete electronic components in order to process signals, or which are implemented partially or completely as a computer program in a computer.
Preferably, the data exchange device is understood to mean one or more devices for carrying out the respective method steps described in connection with the third embodiment, and which, for this purpose, comprises either discrete electronic components in order to process signals, or which are implemented partially or completely as a computer program in a computer. Preferably, the data exchange device is adapted to trigger the first optical imaging device and the second optical imaging device to capture an image. Preferably, the data exchange device is adapted to receive the first optical image from the first optical imaging device and to receive the second optical image from the second optical imaging device, e.g. directly via a data connection line or via a network. Preferably, the data exchange device is adapted to sending the first optical image and the second optical image to the data processing device. Preferably, the data exchange device and / or the data processing device comprises a data output device, e.g. a monitor. Preferably, the data exchange device is configured to receiving an output such as a 3D information or a modification. Preferably, the data exchange device is configured to generating / displaying an output on the data output device. Preferably, the data output device is connected to the data exchange device.
The data exchange device and the data processing device can e.g. be implemented in a single system, e.g. in the form of respective program codes in a single computer or in the form of respective electronic components implemented in the same electronic device. The data processing device can e.g. be a remote computer (on a remote location), e.g. a server reachable via the internet. Preferably, the data processing device receives the images from the data exchange device and calculates a 3D information or a modification. Preferably the data processing device stores the calculated 3D information or the modification, e.g. in a memory or a hard disk drive. Preferably the data processing device sends the calculated 3D information or the modification to a data exchange device or to any device for displaying the 3D information or the modification. Preferably, the data exchange device may be even partially or totally integrated into any or all of the imaging devices.
In an eighth embodiment of the invention, the object is achieved by a computer program (product) comprising instructions to cause the data processing device of the fourth and fifth embodiment to execute the steps of the method according to the first and second embodiment.
Exemplary embodiments of the invention are explained in more detail by means of illustrations:
In an alternative embodiment, the same steps are followed as described above in relation to
The data processing device (60) of the example in
List of reference numerals and factors:
| Number | Date | Country | Kind |
|---|---|---|---|
| 20152201.8 | Jan 2020 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/050735 | 1/14/2021 | WO |
