Aluminum liquid level measurement method and system for holding furnace

Abstract

The present invention relates to the field of liquid level measurement technology, and in particular to a method and system for measuring the molten aluminum level in a holding furnace. The method comprises: obtaining laser signals and echo signals from multiple laser transmissions and receptions of a laser level sensor located above the holding furnace while the furnace is measuring the molten aluminum level; determining the difference between the laser signal and echo signal during each laser transmission and reception; determining the noise content of the echo signal during each laser transmission and reception; obtaining the vertical distance between the molten aluminum surface and the laser level sensor during each laser transmission and reception; and determining the corrected distance between the molten aluminum surface and the laser level sensor to measure the molten aluminum level in the holding furnace. By calculating the noise content of the echo signal, the present invention effectively identifies and suppresses interference with the laser signal caused by spectral noise and refractive index changes due to high-temperature thermal radiation and airflow.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid level measurement, and in particular to a method and system for measuring the level of molten aluminum in a holding furnace. Background Art

[0002] Automotive wheel hub production is typically achieved using low-pressure casting machines, which primarily consist of key components such as a holding furnace, a machine frame, a hydraulic system, and a pressurization system. During production, the molten aluminum level within the holding furnace is a crucial parameter affecting casting quality and production efficiency. A low level can lead to insufficient aluminum supply, compromising the integrity and quality of the wheel hub molding, and even causing production halts. Excessively high levels can cause aluminum overflow, resulting in equipment damage, safety hazards, and environmental pollution. Therefore, monitoring the molten aluminum level has become a critical requirement in the industry.

[0003] Currently, non-contact laser level sensing technology is being applied in this field to avoid the high-temperature corrosion and maintenance challenges associated with traditional contact sensors. Laser level sensors transmit a laser signal to the aluminum liquid surface and receive the reflected echo signal. The sensor calculates the liquid level based on the phase or time difference between the laser and echo signals, achieving high-precision level measurement. This method significantly improves measurement safety and response speed, and is suitable for the extremely high temperatures and harsh environments within holding furnaces.

[0004] However, the long-term high temperatures of the holding furnace result in intense thermal radiation and complex interference from air flow, which can affect the propagation stability of the laser signal. The spectral noise generated by thermal radiation and the refractive index changes caused by the high-temperature airflow can distort the laser signal's echo waveform, reducing the echo signal-to-noise ratio and, in turn, affecting the accuracy of aluminum liquid level measurements in the holding furnace. Therefore, overcoming signal distortion and noise interference caused by factors such as thermal radiation in high-temperature environments, improving echo signal quality, and ensuring measurement stability and accuracy have become urgent challenges. Summary of the Invention

[0005] In order to solve the problem that the long-term high temperature state of the holding furnace causes complex interference such as strong thermal radiation and air flow, which affects the propagation stability of the laser signal, the spectral noise generated by thermal radiation and the refractive index change caused by the high-temperature airflow will cause the echo waveform of the laser signal to be distorted, reduce the signal-to-noise ratio of the echo signal, and thus affect the accuracy of the aluminum liquid level measurement of the holding furnace, the present invention provides a aluminum liquid level measurement method and system for a holding furnace.

[0006] In a first aspect, the present invention provides a method for measuring the level of molten aluminum in a holding furnace, which adopts the following technical solution:

[0007] A method for measuring the level of molten aluminum in a holding furnace comprises the following steps: obtaining laser signals and echo signals from multiple laser emissions and receptions of a laser level sensor above the holding furnace when the holding furnace is measuring the level of molten aluminum; recording any laser emission and reception of the laser level sensor as a target time; determining the difference between the laser signal and the echo signal in the target time according to the distance between the laser signal and the echo signal in the target time and the information entropy of the frequency domain signals of the laser signal and the echo signal in the target time; decomposing the laser signal and the echo signal in the target time to obtain the difference between the laser signal and the echo signal in the target time. Multiple pairs of eigenmode functions corresponding one to one are used to determine the noise level of the echo signal in the target time according to the difference and the maximum value of the cross-correlation function between each pair of eigenmode functions; based on the laser signal and the echo signal in the target time, a measurement method is used to obtain the vertical distance between the liquid surface of the molten aluminum and the laser liquid level sensor at the target time; based on the noise level of the echo signal in each laser emission and reception, and the vertical distance between the liquid surface of the molten aluminum and the laser liquid level sensor in each laser emission and reception, a corrected distance between the liquid surface of the molten aluminum and the laser liquid level sensor is determined to achieve aluminum liquid level measurement in the holding furnace.

[0008] By calculating the frequency domain information entropy difference and the cross-correlation of the intrinsic mode functions between the laser signal and the echo signal, the present invention can accurately determine the noise content of the echo signal, thereby effectively identifying and suppressing the interference of spectral noise and refractive index changes caused by high-temperature thermal radiation and airflow on the laser signal. By utilizing multiple laser transmission and reception data, the noise content of the echo signal is quantified and corrected, which significantly improves the measurement signal-to-noise ratio, reduces waveform distortion, and improves the measurement accuracy and repeatability of the aluminum liquid level. By automatically analyzing the intrinsic mode functions and cross-correlation maximum values of the laser signal and the echo signal, the system can intelligently determine the signal quality, realize automatic correction, reduce human intervention, and improve the automation level of the measurement system. Accurate liquid level measurement ensures the safe operation of the aluminum liquid holding furnace, avoids equipment damage and production interruption caused by liquid level anomalies, and improves overall industrial production efficiency and economic benefits.

[0009] Furthermore, the multiple laser transmission and reception of the laser liquid level sensor are performed at multiple different angles.

[0010] Furthermore, the frequency domain signal is acquired by converting the laser signal and the echo signal using Fourier transform to obtain the frequency domain signal of the laser signal and the frequency domain signal of the echo signal.

[0011] Furthermore, the difference satisfies:

[0012] Where, For the The difference between the laser signal and the echo signal in the laser emission and reception, For the The distance between the laser signal and the echo signal during the laser emission and reception, For the The information entropy of the frequency domain signal of the laser signal in the laser emission and reception, For the The information entropy of the frequency domain signal of the echo signal in the laser emission and reception, is the maximum value function, is the linear normalization function, is the absolute value symbol.

[0013] The present invention combines the relative difference in frequency domain information entropy with the normalized value of distance to quantify the difference index and accurately evaluate the true difference between the laser signal and the echo signal, laying the foundation for subsequent noise determination and correction. The introduction of the normalized distance factor and the maximum value function ensures that the difference calculation is not affected by the signal amplitude, thereby enhancing the applicability and stability of the measurement method under different signal strengths and environmental conditions.

[0014] Furthermore, the distance adopts DTW distance.

[0015] Furthermore, the decomposition adopts empirical mode decomposition.

[0016] Furthermore, the noise level satisfies:

[0017] Where, For the The noise level of the echo signal in the laser emission and reception, For the The difference between the laser signal and the echo signal in the laser emission and reception, For the The number of pairs of eigenmode functions corresponding one-to-one between the laser signal and the echo signal in the laser emission and reception, For the The first of multiple pairs of eigenmode functions corresponding one to one between the laser signal and the echo signal in the laser emission and reception For the sequence number of the eigenmode function, For the The first of multiple pairs of eigenmode functions corresponding one to one between the laser signal and the echo signal in the laser emission and reception For the maximum value of the cross-correlation function between the eigenmode functions, is the natural exponential function.

[0018] The noise level calculated by the present invention combines the difference between the laser signal and the echo signal and the maximum value of the cross-correlation between multiple pairs of eigenmode functions, which can more accurately reflect the noise level of the echo signal and improve the precision of noise discrimination. Through the design of exponential function and weighted summation term, the maximum value of the cross-correlation is weighted attenuated to effectively distinguish between high-correlation and low-correlation modes, reducing the risk of local anomalies affecting the overall noise judgment.

[0019] Furthermore, obtaining the vertical distance between the liquid surface of the aluminum liquid and the laser liquid level sensor at the target time includes: using the phase laser ranging method in the measurement method to calculate the phase difference between the laser signal and the echo signal at the target time, and then obtaining the straight-line distance between the liquid surface of the aluminum liquid and the laser liquid level sensor at the target time; based on the straight-line distance, using the trigonometric function formula in the measurement method, obtaining the vertical distance between the liquid surface of the aluminum liquid and the laser liquid level sensor at the target time.

[0020] The present invention adopts a phase laser ranging method to accurately calculate the straight-line distance using the phase difference between the laser signal and the echo signal, thereby overcoming the measurement errors in traditional ranging methods and improving the resolution and accuracy of liquid level ranging. Combined with trigonometric function formulas, the straight-line distance is converted into the vertical distance between the liquid surface and the sensor, accurately reflecting the actual liquid level height of the aluminum liquid and adapting to the diverse requirements of sensor installation angles and measurement environments.

[0021] Furthermore, the corrected distance satisfies:

[0022] Where, is the corrected distance between the aluminum liquid surface and the laser level sensor, is the number of laser emission and reception of the laser level sensor, For the The noise level of the echo signal in the laser emission and reception, For the The vertical distance between the aluminum liquid surface and the laser level sensor when the laser is emitted and received. is the natural exponential function.

[0023] The present invention significantly reduces the impact of noisy measurement results by weighting the vertical distance of each laser measurement according to the exponential decay of the echo signal noise content, making the overall corrected distance more accurate and reliable, effectively resisting abnormal noise fluctuations caused by thermal radiation and airflow interference, improving the stability of multiple measurement results, and ensuring the consistency and continuity of liquid level data; by integrating the results of multiple laser transmission and reception, using the dynamic weight of the noise content, smoothing the liquid level measurement fluctuations, reducing the measurement deviation caused by single abnormal values, and improving the measurement accuracy of the entire system.

[0024] In a second aspect, the present invention provides an aluminum liquid level measurement system for a holding furnace, which adopts the following technical solution:

[0025] A molten aluminum level measurement system for a holding furnace comprises: a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the above-mentioned molten aluminum level measurement method for a holding furnace is implemented.

[0026] By adopting the above technical solution, the above-mentioned aluminum liquid level measurement method for the holding furnace is generated into a computer program and stored in the memory to be loaded and executed by the processor, so that a terminal device is made based on the memory and the processor for easy use.

[0027] The present invention has the following technical effects:

[0028] (1) A signal difference evaluation system is constructed by comprehensively considering multi-dimensional factors such as the distance between the laser signal and the echo signal, the information entropy of the frequency domain signal, and the maximum value of the intrinsic mode function cross-correlation function; compared with the traditional single measurement method that only relies on the echo time difference, the present invention can more comprehensively capture the influence of complex interference such as thermal radiation and high-temperature airflow on the laser signal, effectively overcome the uncertainty of signal propagation in a high-temperature environment, accurately mine the signal distortion characteristics, and lay the foundation for the accurate judgment of the noise content of the subsequent echo signal, thereby improving the analysis ability of the aluminum liquid level measurement signal.

[0029] (2) When calculating the noise content of the echo signal, the signal difference and the cross-correlation of the intrinsic mode function are comprehensively considered to form a dynamic evaluation mechanism to effectively deal with the noise and abnormal fluctuations in the signal under high temperature environment; compared with the traditional fixed threshold processing method, the improved measurement method has stronger resistance to interference such as spectral noise generated by thermal radiation and signal distortion caused by high temperature airflow, reducing the erroneous measurement results caused by noise and improving the stability and reliability of the measurement model.

[0030] (3) When determining the correction distance of the aluminum liquid level, the noise content of the echo signal received by each laser emission and the vertical distance data are combined, and the actual business needs of the aluminum liquid level measurement in the holding furnace are fully considered. For example, the continuous impact of the high temperature environment on laser propagation and the dynamic characteristics of the liquid level fluctuation are taken into account. This makes the aluminum liquid level measurement method more in line with the industrial production scenario, and the measurement results can effectively reflect the actual liquid level situation, providing effective support for key links such as flow control and composition adjustment in the production process of aluminum liquid in the holding furnace, thereby improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a schematic diagram showing waveform distortion of an echo signal in a method for measuring the level of molten aluminum in a holding furnace according to an embodiment of the present invention.

[0032] Figure 2 This is a flow chart of a method for measuring the level of molten aluminum in a holding furnace according to an embodiment of the present invention.

[0033] Figure 3 This is a front view of multiple laser emissions in a method for measuring the level of molten aluminum in a holding furnace according to an embodiment of the present invention.

[0034] Figure 4 It is a top view of multiple laser shots in a method for measuring the level of molten aluminum in a holding furnace according to an embodiment of the present invention.

[0035] Figure 5 It is a schematic diagram of the straight-line distance and vertical distance between the liquid surface of the molten aluminum and the laser level sensor during multiple laser transmission and reception in a method for measuring the molten aluminum level of a holding furnace according to an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0037] Since the holding furnace is in a high temperature state for a long time, the propagation of the laser is accompanied by interference from factors such as strong thermal radiation. Figure 1 ( Figure 1 This is just a schematic diagram. In actual production, the time difference should be seconds), resulting in waveform distortion of the echo signal, thereby affecting the measurement accuracy of the aluminum liquid level of the holding furnace. Therefore, the embodiment of the present invention discloses a method for measuring the aluminum liquid level of the holding furnace, referring to Figure 2 , including steps S1 to S5:

[0038] S1 obtains the laser signals and echo signals from multiple laser transmissions and receptions of the laser level sensor above the holding furnace when the holding furnace is measuring the aluminum liquid level.

[0039] It should be noted that since the aluminum liquid surface in the holding furnace is in contact with the air, under high temperature conditions, local oxidation of the aluminum liquid surface causes an uneven liquid surface. If the laser signal happens to be captured at the uneven liquid surface, it may cause inaccurate liquid level measurement. Therefore, it is necessary to use multi-angle laser signals to measure the aluminum liquid level to ensure measurement accuracy.

[0040] Specifically, the multiple laser transmission and reception of the laser liquid level sensor are performed at multiple different angles.

[0041] The implementer can set the number and angle of laser emission according to the specific implementation situation. For example, the number of laser emission is 5 times; Figure 3 and 4 As shown, in the laser emission angle, one laser signal is vertically downward, and the rest of the laser signals deviate from the vertical downward direction. Degrees, for example, .

[0042] S2: Determine the difference between the laser signal and the echo signal in each laser transmission and reception.

[0043] It should be noted that, ideally, in a set of signals (each laser transmission and reception), the laser signal and the echo signal should be identical except for the phase. However, due to the influence of the holding furnace environment, a certain amount of noise can be introduced into the echo signal, resulting in a certain difference between the echo signal and the laser signal. The introduction of noise affects the calculation of the phase difference between the echo signal and the laser signal, and thus affects the measurement of the molten aluminum level. Therefore, this step calculates the difference between the laser signal and the echo signal to measure the noise introduced into the echo signal.

[0044] Any laser emission and reception of the laser liquid level sensor is recorded as a target time. The difference between the laser signal and the echo signal in the target time is determined based on the distance between the laser signal and the echo signal in the target time and the information entropy of the frequency domain signals of the laser signal and the echo signal in the target time.

[0045] Specifically, the frequency domain signal is obtained as follows:

[0046] The laser signal and the echo signal are transformed by Fourier transform to obtain the frequency domain signal of the laser signal and the frequency domain signal of the echo signal.

[0047] Specifically, the differences satisfy:

[0048] ;

[0049] Where, For the The difference between the laser signal and the echo signal in the laser emission and reception, For the The distance between the laser signal and the echo signal during the laser emission and reception, For the The information entropy of the frequency domain signal of the laser signal in the laser emission and reception, For the The information entropy of the frequency domain signal of the echo signal in the laser emission and reception, is the maximum value function, is the linear normalization function, is the absolute value symbol.

[0050] Specifically, the distance adopts DTW distance.

[0051] in, Indicates the The difference between the laser signal and the echo signal in the laser emission and reception. The larger the value, the less similar the laser signal and the echo signal are, and the greater the difference between the laser signal and the echo signal; the smaller the value, the more similar the laser signal and the echo signal are, and the smaller the difference between the laser signal and the echo signal. Indicates the The difference in frequency domain signals between the laser signal and the echo signal in the laser emission and reception is due to the inclusion of noise in the echo signal, which results in the presence of frequencies in the echo signal that do not exist in the laser signal, resulting in a certain difference in frequency domain signals between the laser signal and the echo signal. The larger the value, the less similar the laser signal and the echo signal are, and the greater the difference in frequency domain signals between the laser signal and the echo signal; the smaller the value, the more similar the laser signal and the echo signal are, and the smaller the difference in frequency domain signals between the laser signal and the echo signal.

[0052] S3: Determine the noise level of the echo signal in each laser emission and reception.

[0053] It should be noted that a certain amount of noise is introduced into the echo signal as it returns to the laser level sensor. This noise can affect the calculation of the phase difference between the laser and echo signals, and thus the measurement of the molten aluminum level. Therefore, to reduce the interference of noise in the echo signal on the level measurement, this step calculates the noise content of the echo signal based on the difference between the laser and echo signals and the intrinsic mode functions of the two signals.

[0054] The laser signal and the echo signal in the target time are decomposed to obtain multiple pairs of eigenmode functions corresponding to each other in the target time. According to the difference and the maximum value of the cross-correlation function between each pair of eigenmode functions (only the maximum value of the cross-correlation function between components of the same level is calculated, for example, the laser signal is decomposed into , the echo signal is decomposed into , then only calculate and The maximum value of the cross-correlation function between and The maximum value of the cross-correlation function between and The maximum value of the cross-correlation function between the two is used to determine the noise level of the echo signal in the target time.

[0055] Specifically, the decomposition adopts empirical mode decomposition.

[0056] Implementers can set the K value in the empirical mode decomposition according to specific implementation conditions, for example, 4.

[0057] Specifically, the noise level satisfies:

[0058] ;

[0059] Where, For the The noise level of the echo signal in the laser emission and reception, For the The difference between the laser signal and the echo signal in the laser emission and reception, For the The number of pairs of eigenmode functions corresponding one-to-one between the laser signal and the echo signal in the laser emission and reception, For the The first of multiple pairs of eigenmode functions corresponding one to one between the laser signal and the echo signal in the laser emission and reception For the sequence number of the eigenmode function, For the The first of multiple pairs of eigenmode functions corresponding one to one between the laser signal and the echo signal in the laser emission and reception For the maximum value of the cross-correlation function between the eigenmode functions, is the natural exponential function.

[0060] Among them, in an ideal state, the laser signal and the echo signal should be the same. Due to the introduction of noise, there is a certain difference between the echo signal and the laser signal. The more noise is mixed into the echo signal, the greater the difference between the echo signal and the laser signal. The less noise signal is mixed into the echo signal, the smaller the difference between the echo signal and the laser signal. Therefore, The larger the the bigger it is; The smaller the The smaller it is. Represents the laser signal and the echo signal As for the similarity between the eigenmode functions, since the empirical mode decomposition can decompose the signal into several eigenmode functions, the eigenmode functions of the same signal decomposed by the empirical mode decomposition should also be similar. However, there will be noise in the echo signal, which makes there a certain difference between the eigenmode function of the laser signal and the eigenmode function of the echo signal. The greater the difference, the more noise is mixed into the echo signal, and the smaller the difference, the less noise is mixed into the echo signal. Therefore, The larger the value is, the less noise is added to the echo signal. The smaller it is; The smaller it is, the more noise is mixed into the echo signal. The bigger it is. The value range of is from -1 to 1, so in the formula Add 1 and divide by 2 to complete the Normalization operation is performed to facilitate subsequent calculations. Since the empirical mode decomposition will first decompose the high-frequency components in the signal, and noise is usually high-frequency, the earlier the eigenmode function is decomposed, the more likely it is to contain more noise signals. Therefore, the earlier the eigenmode function is decomposed, the more important it is for calculating the noise level of the echo signal. Therefore, As The weight of is set so that the eigenmode function that is decomposed earlier has a higher weight for the calculation of the noise level of the echo signal, and the eigenmode function that is decomposed later has a lower weight for the calculation of the noise level of the echo signal.

[0061] S4: Obtain the vertical distance between the aluminum liquid surface and the laser level sensor during each laser emission and reception.

[0062] Based on the laser signal and echo signal at the target time, the vertical distance between the liquid surface of the aluminum liquid and the laser level sensor at the target time is obtained by using the measurement method.

[0063] Specifically, obtaining the vertical distance between the liquid surface of the aluminum liquid and the laser liquid level sensor at the target time includes:

[0064] The phase laser ranging method in the measurement method is used to calculate the phase difference between the laser signal and the echo signal at the target time, and then the straight-line distance between the liquid surface of the aluminum liquid and the laser level sensor at the target time is obtained;

[0065] Based on the straight-line distance, the vertical distance between the liquid surface of the molten aluminum and the laser liquid level sensor at the target time is obtained using the trigonometric function formula in the measurement method.

[0066] Among them, Figure 5 As shown in the figure, is the deviation angle, is the straight-line distance, =The vertical distance. For laser emission at an angle off vertical, the linear distance is the distance obtained each time the laser is emitted at an angle off vertical, and the vertical distance is the vertical distance between the sensor and the liquid surface. For laser emission at a vertical angle, after the linear distance is obtained, the vertical distance is equal to the linear distance. Phase laser ranging and trigonometric formulas are both existing technologies and will not be further described here.

[0067] S5: Determine the corrected distance between the liquid surface of the molten aluminum and the laser liquid level sensor to achieve the molten aluminum level measurement of the holding furnace.

[0068] It should be noted that the noise level of the echo signal affects the reliability of vertical distance measurement. A noisier signal corresponds to a lower confidence level, while a noisier signal corresponds to a higher confidence level. Therefore, this step uses a weighted average to weight the vertical distances measured using the noise level of the echo signal. This eliminates data with significant noise interference and retains highly reliable measurements, resulting in a more accurate liquid level measurement.

[0069] Based on the noise level of the echo signal in each laser emission and reception, as well as the vertical distance between the aluminum liquid surface and the laser liquid level sensor during each laser emission and reception, the corrected distance between the aluminum liquid surface and the laser liquid level sensor is determined to achieve aluminum liquid level measurement in the holding furnace.

[0070] Specifically, the corrected distance satisfies:

[0071] ;

[0072] Where, is the corrected distance between the aluminum liquid surface and the laser level sensor, is the number of laser emission and reception of the laser level sensor, For the The noise level of the echo signal in the laser emission and reception, For the The vertical distance between the aluminum liquid surface and the laser level sensor when the laser is emitted and received. is the natural exponential function.

[0073] Among them, the vertical distance corresponding to the echo signal with a higher degree of noise should have a lower degree of importance to the final distance between the aluminum liquid surface and the laser liquid level sensor, and occupy a smaller proportion; the vertical distance corresponding to the echo signal with a lower degree of noise should have a higher degree of importance to the final distance between the aluminum liquid surface and the laser liquid level sensor. Therefore, As The weight of is used to calculate the distance between the aluminum liquid surface and the laser liquid level sensor. Since the overall height of the holding furnace and the setting position of the laser liquid level sensor are known, the height of the aluminum liquid level of the holding furnace is obtained.

[0074] An embodiment of the present invention further discloses an aluminum liquid level measurement system for a holding furnace, comprising a processor and a memory, wherein the memory stores computer program instructions. When the computer program instructions are executed by the processor, an aluminum liquid level measurement method for a holding furnace according to the present invention is implemented.

[0075] The above system also includes other components well known to those skilled in the art, such as a communication bus and a communication interface. The configuration and functions of these components are known in the art and will not be described in detail here.

[0076] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for measuring the level of molten aluminum in a holding furnace, characterized in that: include: Acquire the laser signals and echo signals from multiple laser transmissions and receptions of the laser level sensor above the holding furnace when the holding furnace is measuring the aluminum liquid level; Any laser emission and reception of the laser liquid level sensor is recorded as a target time, and the difference between the laser signal and the echo signal in the target time is determined based on the distance between the laser signal and the echo signal in the target time and the information entropy of the frequency domain signals of the laser signal and the echo signal in the target time; Decomposing the laser signal and the echo signal in the target time to obtain a plurality of pairs of eigenmode functions corresponding one to one between the laser signal and the echo signal in the target time, and determining the noise level of the echo signal in the target time based on the difference and the maximum value of the cross-correlation function between each pair of eigenmode functions; Based on the laser signal and echo signal at the target time, the vertical distance between the liquid surface of the aluminum liquid and the laser level sensor at the target time is obtained by using the measurement method; Based on the noise level of the echo signal in each laser emission and reception, as well as the vertical distance between the aluminum liquid surface and the laser liquid level sensor during each laser emission and reception, the corrected distance between the aluminum liquid surface and the laser liquid level sensor is determined to achieve aluminum liquid level measurement in the holding furnace.

2. The method for measuring the aluminum liquid level of a holding furnace according to claim 1, wherein: The multiple laser transmission and reception of the laser liquid level sensor are performed at multiple different angles.

3. The method for measuring the aluminum liquid level of a holding furnace according to claim 1, wherein: The frequency domain signal is obtained as follows: The laser signal and the echo signal are transformed by Fourier transform to obtain the frequency domain signal of the laser signal and the frequency domain signal of the echo signal.

4. The method for measuring the aluminum liquid level in a holding furnace according to claim 1, wherein: The differences satisfy: ； Where, For the The difference between the laser signal and the echo signal in the laser emission and reception, For the The distance between the laser signal and the echo signal during the laser emission and reception, For the The information entropy of the frequency domain signal of the laser signal in the laser emission and reception, For the The information entropy of the frequency domain signal of the echo signal in the laser emission and reception, is the maximum value function, is the linear normalization function, is the absolute value symbol.

5. A method for measuring the aluminum liquid level in a holding furnace according to claim 1 or 4, characterized in that: The distance adopts DTW distance.

6. The method for measuring the aluminum liquid level in a holding furnace according to claim 1, wherein: The decomposition adopts empirical mode decomposition.

7. The method for measuring the aluminum liquid level in a holding furnace according to claim 1, wherein: The noise level satisfies: ； Where, For the The noise level of the echo signal in the laser emission and reception, For the The difference between the laser signal and the echo signal in the laser emission and reception, For the The number of pairs of eigenmode functions corresponding one-to-one between the laser signal and the echo signal in the laser emission and reception, For the The first of multiple pairs of eigenmode functions corresponding one to one between the laser signal and the echo signal in the laser emission and reception For the sequence number of the eigenmode function, For the The first of multiple pairs of eigenmode functions corresponding one to one between the laser signal and the echo signal in the laser emission and reception For the maximum value of the cross-correlation function between the eigenmode functions, is the natural exponential function.

8. The method for measuring the aluminum liquid level in a holding furnace according to claim 1, wherein: The vertical distance between the liquid surface of the molten aluminum and the laser liquid level sensor at the target time is obtained, including: The phase laser ranging method in the measurement method is used to calculate the phase difference between the laser signal and the echo signal at the target time, and then the straight-line distance between the liquid surface of the aluminum liquid and the laser level sensor at the target time is obtained; Based on the straight-line distance, the vertical distance between the liquid surface of the molten aluminum and the laser liquid level sensor at the target time is obtained using the trigonometric function formula in the measurement method.

9. The method for measuring the aluminum liquid level in a holding furnace according to claim 1, wherein: The corrected distance satisfies: ； Where, is the corrected distance between the aluminum liquid surface and the laser level sensor, is the number of laser emission and reception of the laser level sensor, For the The noise level of the echo signal in the laser emission and reception, For the The vertical distance between the aluminum liquid surface and the laser level sensor when the laser is emitted and received. is the natural exponential function.

10. A molten aluminum level measurement system for a holding furnace, characterized in that: include: A processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, an aluminum liquid level measurement method for a holding furnace according to any one of claims 1 to 9 is implemented.

Images