Molten aluminum liquid level measuring method and system for holding furnace

Abstract

The invention relates to the technical field of liquid level measurement, in particular to a molten aluminum liquid level measurement method and system for a holding furnace. The method comprises the following steps: acquiring laser signals and echo signals in multiple laser emission and reception of a laser liquid level sensor above the holding furnace when the holding furnace is used for measuring the liquid level of molten aluminum; determining the difference between the laser signal and the echo signal in each laser emission and reception; determining the noisy degree of the echo signal in each laser emission and reception; acquiring the vertical distance between the liquid level of the molten aluminum and the laser liquid level sensor when the laser is emitted and received each time; and the correction distance between the liquid level of the molten aluminum and the laser liquid level sensor is determined so as to measure the liquid level of the molten aluminum of the holding furnace. According to the method, the noise-containing degree of the echo signal is calculated, so that the interference of spectral noise and refractive index change caused by high-temperature heat radiation and airflow on the laser signal is effectively identified and inhibited.

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 liquid level of molten aluminum in a holding furnace. Background Art

[0002] The production of automobile wheels is usually achieved through low-pressure casting machines, which mainly include key components such as holding furnaces, racks, hydraulic systems and pressurization systems. During production, the liquid level of molten aluminum in the holding furnace is an important parameter that affects casting quality and production efficiency. A too low liquid level may lead to insufficient supply of molten aluminum, affecting the integrity and quality of wheel hub molding, and even causing production stagnation; while a too high liquid level may cause molten aluminum to overflow, causing equipment damage, safety hazards and production environment pollution. Therefore, monitoring the liquid level of molten aluminum has become a key demand in the industry.

[0003] Currently, non-contact laser level sensing technology is used in this field to avoid high temperature corrosion and maintenance problems caused by traditional contact sensors. The laser level sensor transmits a laser signal to the aluminum liquid surface and receives the reflected echo signal. It calculates the liquid level according to the phase difference or time difference between the laser signal and the echo signal, thereby achieving high-precision liquid level measurement. This method greatly improves the safety and response speed of measurement, and adapts to the extremely high temperature and harsh environment in the holding furnace.

[0004] However, the holding furnace is in a high temperature state for a long time, resulting in strong thermal radiation and complex interference such as air flow, which will affect the propagation stability of the laser signal. The spectral noise generated by thermal radiation and the refractive index change caused by high-temperature airflow will distort the echo waveform of the laser signal, 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. Therefore, how to overcome the signal distortion and noise interference caused by factors such as thermal radiation in a high temperature environment, improve the quality of the echo signal, and ensure the stability and accuracy of the measurement has become an urgent problem to be solved. Summary of the invention

[0005] In order to solve the problem that the long-term high temperature state of the holding furnace causes complex interferences such as strong thermal radiation and air flow, which will affect the propagation stability of the laser signal, the spectral noise generated by the 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 further affect the accuracy of the aluminum liquid level measurement of the holding furnace, the present invention provides an 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: A method for measuring the liquid level of molten aluminum in a holding furnace, comprising: obtaining laser signals and echo signals during multiple laser emissions and receptions of a laser level sensor above the holding furnace when measuring the liquid level of molten aluminum in the holding furnace; designating any one laser emission and reception of the laser level sensor as the target time, and 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 multiple pairs of corresponding intrinsic mode functions between the laser signal and the echo signal in the target time, and determining the noise content 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 intrinsic mode functions; based on the laser signal and the echo signal in the target time, using a measurement method to obtain the vertical distance between the liquid surface of the molten aluminum and the laser level sensor at the target time; and determining the corrected distance between the liquid surface of the molten aluminum and the laser level sensor according to the noise content of the echo signal during each laser emission and reception and the vertical distance between the liquid surface of the molten aluminum and the laser level sensor during each laser emission and reception, so as to realize the measurement of the liquid level of molten aluminum in the holding furnace.

[0007] By calculating the difference in the frequency domain information entropy between the laser signal and the echo signal and the cross-correlation of the intrinsic mode functions, the present invention can accurately judge 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 air flow on the laser signal; by using multiple laser emission and reception data, through quantifying and correcting the noise content of the echo signal, the signal-to-noise ratio of the measurement is significantly improved, waveform distortion is reduced, and the measurement accuracy and repeat stability of the liquid level of molten aluminum are improved; by automatically analyzing the intrinsic mode functions of the laser signal and the echo signal and the maximum value of the cross-correlation, the system can intelligently judge the signal quality, realize automatic correction, reduce human intervention, and improve the automation level of the measurement system; accurate liquid level measurement ensures the safety of the operation of the molten aluminum holding furnace, avoids equipment damage and production interruption caused by abnormal liquid levels, and improves the overall industrial production efficiency and economic benefits.

[0008] Further, the multiple laser emissions and receptions of the laser level sensor are carried out at multiple different angles.

[0009] Further, the obtaining method of the frequency domain signal is: using Fourier transform to transform the laser signal and the echo signal to obtain the frequency domain signal of the laser signal and the frequency domain signal of the echo signal.

[0010] Further, the difference satisfies: ; where is the difference between the laser signal and the echo signal in the th laser emission and reception, is the distance between the laser signal and the echo signal in the th laser emission and reception, is the information entropy of the frequency-domain signal of the laser signal in the th laser emission and reception, is the information entropy of the frequency-domain signal of the echo signal in the th laser emission and reception, is the maximum value function, is the linear normalization function, is the absolute value symbol.

[0011] The present invention combines the relative difference of the frequency-domain information entropy and the normalized value of the distance to quantify the difference index, accurately evaluate the true difference between the laser signal and the echo signal, and lay a foundation for subsequent noise determination and correction; introduce the normalized distance factor and the maximum value function to ensure that the difference calculation is not affected by the signal amplitude size, and enhance the applicability and stability of the measurement method under different signal intensities and environmental conditions.

[0012] Further, the distance adopts the DTW distance.

[0013] Further, the decomposition adopts empirical mode decomposition.

[0014] Further, the noise content satisfies: ; where is the noise content of the echo signal in the th laser emission and reception, is the difference between the laser signal and the echo signal in the th laser emission and reception, is the number of pairs of corresponding intrinsic mode functions between the laser signal and the echo signal in the th laser emission and reception, is the th pair of corresponding intrinsic mode functions between the laser signal and the echo signal in the th laser emission and reception, is the th pair of corresponding intrinsic mode functions between the laser signal and the echo signal in the th laser emission and reception, is the maximum value of the cross-correlation function between the

[0015] The noise level calculated by the present invention combines the difference between the laser signal and the echo signal and the maximum cross-correlation between multiple pairs of intrinsic mode functions, which can more accurately reflect the noise level of the echo signal and improve the fineness of noise discrimination; through the design of the exponential function and the weighted summation term, the maximum cross-correlation is weighted and attenuated, effectively distinguishing high-correlation and low-correlation modes, and reducing the risk of affecting the overall noise judgment due to local anomalies.

[0016] Further, the obtaining of the vertical distance between the liquid level of the molten aluminum at the target time and the laser level sensor includes: calculating the phase difference between the laser signal and the echo signal in the target time by using the phase laser ranging method in the measurement method, and then obtaining the straight-line distance between the liquid level of the molten aluminum at the target time and the laser level sensor; based on the straight-line distance, using the trigonometric function formula in the measurement method to obtain the vertical distance between the liquid level of the molten aluminum at the target time and the laser level sensor.

[0017] By adopting the phase laser ranging method, the present invention accurately calculates the straight-line distance by using the phase difference between the laser signal and the echo signal, overcomes the measurement error in the traditional ranging method, and improves the resolution and accuracy of liquid level ranging; combined with the trigonometric function formula, the straight-line distance is converted into the vertical distance between the liquid level and the sensor, accurately reflecting the actual liquid level height of the molten aluminum and meeting the requirements of diverse installation angles of the sensor and measurement environments.

[0018] Further, the corrected distance satisfies: ; in the formula, is the corrected distance between the liquid level of the molten aluminum and the laser level sensor, is the number of times of multiple laser emissions and receptions of the laser level sensor, is the noise level of the echo signal in the th laser emission and reception, is the vertical distance between the liquid level of the molten aluminum and the laser level sensor at the th laser emission and reception, and

[0019] is the natural exponential function.

[0020] Second aspect, the present invention provides an aluminum liquid level measurement system for a holding furnace, adopting the following technical solution: An aluminum liquid level measurement system for a holding furnace, comprising: a processor and a memory, the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the above-mentioned aluminum liquid level measurement method for a holding furnace is implemented.

[0021] By adopting the above technical solution, the above-mentioned aluminum liquid level measurement method for a holding furnace is generated into a computer program and stored in the memory to be loaded and executed by the processor, so as to manufacture a terminal device according to the memory and the processor, which is convenient to use.

[0022] The present invention has the following technical effects: (1) 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 cross-correlation function of the intrinsic mode functions, a signal difference evaluation system is constructed; compared with the traditional single measurement method that only relies on the echo time difference, the present invention can capture the influence of complex interferences such as thermal radiation and high-temperature air flow on the laser signal more comprehensively, effectively overcome the uncertainty of signal propagation in a high-temperature environment, accurately excavate the signal distortion characteristics, and lay a foundation for the accurate determination of the noise level of the subsequent echo signal, thereby improving the analytical ability of the aluminum liquid level measurement signal.

[0023] (2) When calculating the noise level of the echo signal, the signal difference and the cross-correlation of the intrinsic mode functions are comprehensively considered to form a dynamic evaluation mechanism, effectively dealing with the noise and abnormal fluctuations in the signal in a 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 air flow, reduces the error measurement results caused by noise, and improves the stability and reliability of the measurement model.

[0024] (3) When determining the correction distance of the aluminum liquid level, by combining the noise level of the echo signal and the vertical distance data received each time the laser is emitted, the actual business requirements of the aluminum liquid level measurement in the holding furnace are fully considered. For example, the continuous influence of the high-temperature environment on laser propagation, the dynamic characteristics of liquid level fluctuations, etc., making the aluminum liquid level measurement method more in line with the industrial production scenario, and the measurement results can truly reflect the actual liquid level situation, providing effective support for key links such as flow control and composition adjustment in the aluminum liquid production process of the holding furnace, and improving production efficiency. Description of the Drawings

[0025] Figure 1 It is a schematic diagram of waveform distortion of the echo signal in an aluminum liquid level measurement method for a holding furnace according to an embodiment of the present invention.

[0026] Figure 2It is the flowchart of a method for measuring the liquid level of molten aluminum in a holding furnace according to an embodiment of the present invention.

[0027] Figure 3 It is the front view of multiple laser emissions in a method for measuring the liquid level of molten aluminum in a holding furnace according to an embodiment of the present invention.

[0028] Figure 4 It is the top view of multiple laser emissions in a method for measuring the liquid level of molten aluminum in a holding furnace according to an embodiment of the present invention.

[0029] Figure 5 It is a schematic diagram of the straight-line distance and the vertical distance between the liquid surface of molten aluminum and the laser liquid level sensor during multiple laser emissions and receptions in a method for measuring the liquid level of molten aluminum in a holding furnace according to an embodiment of the present invention. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0031] Due to the holding furnace being in a high-temperature state for a long time, the propagation of laser is accompanied by interference factors such as strong thermal radiation. Referring to Figure 1 ( Figure 1 It is only a schematic diagram. In actual production, the time difference should be seconds), which causes waveform distortion of the echo signal, thereby affecting the measurement accuracy of the liquid level of molten aluminum in the holding furnace. Therefore, an embodiment of the present invention discloses a method for measuring the liquid level of molten aluminum in a holding furnace. Referring to Figure 2 , it includes steps S1 - step S5: S1 Obtain the laser signal and the echo signal in multiple laser emissions and receptions of the laser liquid level sensor above the holding furnace when measuring the liquid level of molten aluminum in the holding furnace.

[0032] It should be noted that since the liquid surface of molten aluminum in the holding furnace is in contact with air, under high-temperature conditions, local oxidation of the liquid surface of molten aluminum causes the liquid surface to be uneven. If the laser signal just enters the uneven part of the liquid surface, it may lead to inaccurate measurement of the liquid surface. Therefore, it is necessary to measure the liquid level of molten aluminum through laser signals at multiple angles to ensure the accuracy of the measurement.

[0033] Specifically, the multiple laser emissions and receptions of the laser liquid level sensor are carried out at multiple different angles.

[0034] The implementer can set the number of laser emissions and the angle according to the specific implementation situation. For example, the number of laser emissions is 5 times; as Figure 3 and 4 shown, among the laser emission angles, one of the laser signals is vertically downward, and the remaining laser signals deviate from vertically downward degrees. Exemplarily, .

[0035] S2: Determine the difference between the laser signal and the echo signal in each laser emission and reception.

[0036] It should be noted that in the ideal state, in a set of signals (each laser emission and reception), the laser signal and the echo signal should be the same except for the phase. However, due to the influence of the environment where the holding furnace is located, certain noise will be introduced into the echo signal, resulting in a certain difference between the echo signal and the laser signal. The introduction of noise will affect the calculation of the phase difference between the echo signal and the laser signal, and thus affect the measurement of the aluminum liquid level. Therefore, this step is to measure the situation of the noise introduced into the echo signal and calculate the difference between the laser signal and the echo signal.

[0037] Record any laser emission and reception of the laser level sensor as 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, determine the difference between the laser signal and the echo signal in the target time.

[0038] Specifically, the acquisition method of the frequency domain signal is as follows: Use Fourier transform to transform the laser signal and the echo signal to obtain the frequency domain signal of the laser signal and the frequency domain signal of the echo signal.

[0039] Specifically, the difference satisfies: ; In the formula, is the difference between the laser signal and the echo signal in the th laser emission and reception, is the distance between the laser signal and the echo signal in the th laser emission and reception, is the information entropy of the frequency domain signal of the laser signal in the th laser emission and reception, is the information entropy of the frequency domain signal of the echo signal in the th laser emission and reception, is the maximum value function, is the linear normalization function, is the absolute value symbol.

[0040] Specifically, the distance uses the DTW distance.

[0041] Among them, represents the difference between the laser signal and the echo signal in the th laser emission and reception. The larger this value is, 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 this value is, the more similar the laser signal and the echo signal are, and the smaller the difference between the laser signal and the echo signal. represents the difference between the laser signal and the echo signal in the frequency-domain signal in the th laser emission and reception. Since noise is incorporated into the echo signal, there will be frequencies in the echo signal that do not exist in the laser signal, resulting in a certain difference between the laser signal and the echo signal in the frequency-domain signal. The larger this value is, the less similar the laser signal and the echo signal are, and the greater the difference between the laser signal and the echo signal in the frequency-domain signal; the smaller this value is, the more similar the laser signal and the echo signal are, and the smaller the difference between the laser signal and the echo signal in the frequency-domain signal.

[0042] S3: Determine the noise content level of the echo signal in each laser emission and reception.

[0043] It should be noted that during the process of the echo signal returning to the laser liquid level sensor, a certain amount of noise will be incorporated. The noise will affect the calculation of the phase difference between the laser signal and the echo signal, and thus affect the measurement of the aluminum liquid level. Therefore, in this step, in order to weaken the interference of the noise in the echo signal on the liquid level measurement, according to the difference between the laser signal and the echo signal and the intrinsic mode functions of the two signals, the noise content level of the echo signal is calculated.

[0044] Decompose the laser signal and the echo signal in the target time to obtain multiple pairs of corresponding intrinsic mode functions between the laser signal and the echo signal in the target time. According to the difference, and the maximum value of the cross-correlation function between each pair of intrinsic mode functions (only calculate the maximum value of the cross-correlation function between components at the same level. For example, if the laser signal is decomposed into , and the echo signal is decomposed into , then only calculate 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 and ), determine the noise content level of the echo signal in the target time.

[0045] Specifically, the decomposition uses empirical mode decomposition.

[0046] Implementers can set the K value in the empirical mode decomposition according to the specific implementation situation. For example, 4.

[0047] Specifically, the noise level satisfies: ; In the formula, is the noise level of the echo signal in the th laser emission and reception, is the difference between the laser signal and the echo signal in the th laser emission and reception, is the number of pairs of intrinsic mode functions that correspond one-to-one between the laser signal and the echo signal in the th laser emission and reception, is the th pair of the sequence numbers of the pairs of intrinsic mode functions that correspond one-to-one between the laser signal and the echo signal in the th laser emission and reception, is the th pair of the maximum value of the cross-correlation function between the pairs of intrinsic mode functions that correspond one-to-one between the laser signal and the echo signal in the th laser emission and reception, is the natural exponential function.

[0048] Among them, in the 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 incorporated into the echo signal, the greater the difference between the echo signal and the laser signal. The less noise signal is incorporated into the echo signal, the smaller the difference between the echo signal and the laser signal. Therefore, the larger it is, the larger it will be; the smaller it is, the smaller it will be. represents the similarity degree between the th pair of intrinsic mode functions of the laser signal and the echo signal. Since the empirical mode decomposition can decompose the signal into several intrinsic mode functions, the intrinsic mode functions obtained by decomposing the same signal through the empirical mode decomposition should also be similar. However, there will be noise in the echo signal, resulting in a certain difference between the intrinsic mode functions of the laser signal and the intrinsic mode functions of the echo signal. The greater this difference is, the more noise is incorporated into the echo signal. The smaller this difference is, the less noise is incorporated into the echo signal. Therefore the larger it is, the less noise is incorporated into the echo signal, then the smaller it will be; the smaller it is, the more noise is incorporated into the echo signal, then the larger it will be. Since The value range of is from -1 to 1. Therefore, in the formula, by adding 1 to and then dividing by 2, the normalization operation of is completed to facilitate subsequent calculations. Since empirical mode decomposition will first decompose the high-frequency components in the signal, and noise is usually high-frequency, the more eigenmode functions that are decomposed first are more likely to contain more noise signals. Therefore, the more eigenmode functions that are decomposed first are more important for calculating the noise content of the echo signal. Therefore, is used as

[0049] S4: Obtain the vertical distance between the liquid level of the molten aluminum and the laser level sensor each time the laser is emitted and received.

[0050] Based on the laser signal and the echo signal in the target time, use the measurement method to obtain the vertical distance between the liquid level of the molten aluminum and the laser level sensor at the target time.

[0051] Specifically, the obtaining of the vertical distance between the liquid level of the molten aluminum and the laser level sensor at the target time includes: Use the phase laser ranging method in the measurement method to calculate the phase difference between the laser signal and the echo signal in the target time, and then obtain the straight-line distance between the liquid level of the molten aluminum and the laser level sensor at the target time; Based on the straight-line distance, use the trigonometric function formula in the measurement method to obtain the vertical distance between the liquid level of the molten aluminum and the laser level sensor at the target time.

[0052] Among them, as Figure 5 shown in the figure, is the deviation angle, is the straight-line distance, is the vertical distance; for the laser emission at a deviation from the vertical angle, the straight-line distance is the distance obtained each time the laser is emitted at a deviation from the vertical angle, and the vertical distance is the vertical distance between the sensor and the liquid level; for the laser emitted at the vertical angle, after obtaining the straight-line distance, the vertical distance is equal to the straight-line distance. The phase laser ranging method and the trigonometric function formula are both existing technologies and will not be elaborated here.

[0053] S5: Determine the corrected distance between the liquid level of the molten aluminum and the laser level sensor to achieve the measurement of the liquid level of the molten aluminum in the holding furnace.

[0054] It should be noted that since the noise level of the echo signal affects the reliability of the vertical distance measurement, the higher the noise level of the signal, the lower the credibility of the corresponding vertical distance, and vice versa. Therefore, in this step, the noise level of the echo signal is used to assign weights to the vertical distances measured each time through weighted averaging, so as to eliminate the data with large noise interference and retain the measurement values with high credibility, thereby obtaining a more accurate liquid level measurement result.

[0055] According to the noise level of the echo signal in each laser emission and reception, and the vertical distance between the liquid level of the molten aluminum and the laser liquid level sensor during each laser emission and reception, determine the corrected distance between the liquid level of the molten aluminum and the laser liquid level sensor to achieve the measurement of the liquid level of the molten aluminum in the holding furnace.

[0056] Specifically, the corrected distance satisfies: ; In the formula, is the corrected distance between the liquid level of the molten aluminum and the laser liquid level sensor, is the number of times of multiple laser emissions and receptions of the laser liquid level sensor, is the th noise level of the echo signal in the laser emission and reception, is the th vertical distance between the liquid level of the molten aluminum and the laser liquid level sensor during the laser emission and reception, is the natural exponential function.

[0057] Among them, the higher the noise level of the echo signal, the lower the importance of the corresponding vertical distance to the final distance between the liquid level of the molten aluminum and the laser liquid level sensor, occupying a smaller proportion; the lower the noise level of the echo signal, the higher the importance of the corresponding vertical distance to the final distance between the liquid level of the molten aluminum and the laser liquid level sensor. Therefore, is used as 's weight to calculate the distance between the liquid level of the molten aluminum and the laser liquid level sensor. Since the overall height of the holding furnace and the installation position of the laser liquid level sensor are known, the height of the liquid level of the molten aluminum in the holding furnace can be obtained.

[0058] An embodiment of the present invention also discloses a molten aluminum liquid level measurement system for a holding furnace, including a processor and a memory. The memory stores computer program instructions, and when the computer program instructions are executed by the processor, it realizes a method for measuring the molten aluminum liquid level of a holding furnace according to the present invention.

[0059] The above system also includes other components well known to those skilled in the art such as a communication bus and a communication interface. Their settings and functions are known in the art, so they will not be elaborated here.

[0060] The above are all preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby. Therefore, all equivalent changes made according to the structure, shape and principle of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A method for measuring the liquid level of molten aluminum in a holding furnace, characterized in that, Including: Obtaining the laser signal and the echo signal in multiple laser emissions and receptions of the laser level sensor above the holding furnace when measuring the liquid level of molten aluminum in the holding furnace; Denoting any one laser emission and reception of the laser level sensor as the target time, and 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 multiple pairs of corresponding intrinsic mode functions between the laser signal and the echo signal in the target time, and determining the noise content degree 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 intrinsic mode functions; Based on the laser signal and the echo signal in the target time, using the measurement method to obtain the vertical distance between the liquid level of molten aluminum and the laser level sensor at the target time; Determining the corrected distance between the liquid level of molten aluminum and the laser level sensor according to the noise content degree of the echo signal in each laser emission and reception and the vertical distance between the liquid level of molten aluminum and the laser level sensor in each laser emission and reception, so as to realize the measurement of the liquid level of molten aluminum in the holding furnace.

2. The aluminum liquid level measurement method for a holding furnace according to claim 1, characterized in that, The multiple laser emissions and receptions of the laser level sensor are carried out at multiple different angles.

3. A method for measuring the liquid aluminum level of a holding furnace according to claim 1, characterized in that, The acquisition method of the frequency domain signal is as follows: Using Fourier transform to transform the laser signal and the echo signal to obtain the frequency domain signal of the laser signal and the frequency domain signal of the echo signal.

4. A method for measuring the liquid level of molten aluminum in a holding furnace according to claim 1, characterized in that, The difference satisfies: ； In the formula, is the difference between the laser signal and the echo signal in the th laser emission and reception, is the distance between the laser signal and the echo signal in the th laser emission and reception, is the information entropy of the frequency-domain signal of the laser signal in the th laser emission and reception, is the information entropy of the frequency-domain signal of the echo signal in the th 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 liquid aluminum level of a holding furnace according to claim 1 or 4, characterized in that, The distance adopts the DTW distance.

6. A method for measuring the liquid aluminum level of a holding furnace according to claim 1, characterized in that, The decomposition adopts empirical mode decomposition.

7. A method for measuring the liquid aluminum level of a holding furnace according to claim 1, characterized in that, The noise content degree satisfies: ； In the formula, is the noise level of the echo signal in the -th laser emission and reception, is the difference between the laser signal and the echo signal in the -th laser emission and reception, is the number of multiple pairs of eigenmode functions that correspond one-to-one between the laser signal and the echo signal in the -th laser emission and reception, is the sequence number of the -th pair of eigenmode functions that correspond one-to-one between the laser signal and the echo signal in the -th laser emission and reception, is the maximum value of the cross-correlation function between the -th pair of eigenmode functions that correspond one-to-one between the laser signal and the echo signal in the -th laser emission and reception, is the natural exponential function.

8. A method for measuring the liquid aluminum level of a holding furnace according to claim 1, characterized in that, The obtaining of the vertical distance between the liquid level of molten aluminum and the laser level sensor at the target time includes: Calculating the phase difference between the laser signal and the echo signal in the target time by using the phase laser ranging method in the measurement method, and further obtaining the straight-line distance between the liquid level of molten aluminum and the laser level sensor at the target time; Based on the straight-line distance, using the trigonometric function formula in the measurement method to obtain the vertical distance between the liquid level of molten aluminum and the laser level sensor at the target time.

9. A method for measuring the liquid aluminum level of a heat-insulating furnace according to claim 1, characterized in that, The corrected distance satisfies: ； Wherein, is the corrected distance between the liquid level of the molten aluminum and the laser level sensor, is the number of times of multiple laser emissions and receptions of the laser level sensor, is the noise level of the echo signal in the th laser emission and reception, is the vertical distance between the liquid level of the molten aluminum and the laser level sensor during the th laser emission and reception, and is the natural exponential function.

10. An aluminum liquid level measurement system for a holding furnace, characterized in that, Including: A processor and a memory, where the memory stores computer program instructions, and when the computer program instructions are executed by the processor, it realizes a method for measuring the liquid level of molten aluminum in a holding furnace according to any one of claims 1-9.

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