Intelligent Recognition Method for Dust Accumulation State of Ultrasonic Wind Speed Sensor

Abstract

The present invention relates to an intelligent recognition method for the dust accumulation state of an ultrasonic wind speed sensor, belonging to the fields of ultrasonic velocity measurement technology and intelligent sensors. This method utilizes the relationship between the dust accumulation degree and the amplitude of the ultrasonic received signal, and identifies the dust adhesion degree on the surface of the ultrasonic transducer or the sound wave reflection surface by detecting the change in the signal amplitude. After processing the dust adhesion degree and comparing it with a set threshold, a warning prompt is given when the threshold is exceeded. Specifically, after the ultrasonic transducer detects the ultrasonic signal, it is sent to a signal amplification circuit, where the original signal is shaped by the signal amplification circuit, and then the ultrasonic signal is amplified in gain by an AGC regulator; the dust adhesion degree is calculated and discretized, and the discretized dust adhesion degree is compared with a preset threshold, and whether a warning prompt is required is judged according to the comparison result. The present invention can avoid the phenomenon that the measurement accuracy of the sensor decreases or it cannot work due to the failure to clean the dust in time, and enhance the data reliability of the sensor.

Description

Technical Field

[0001] The present invention belongs to the fields of ultrasonic velocity measurement technology and intelligent sensors, and relates to an intelligent recognition method for the dust accumulation state of an ultrasonic wind speed sensor. Background Art

[0002] Ultrasonic wind speed and direction sensors and ultrasonic flow meters based on the ultrasonic time difference principle have the advantages of little influence of ambient temperature, low lower limit, wide range, high precision, good linearity, and no pressure loss, and gradually replace technologies such as differential pressure type, thermal type, and vortex street type, and have become the core technologies in the fields of meteorology and precision measurement. In applications where ultrasonic sensors are required to perform real-time monitoring of wind speed, flow rate, etc., dust accumulation may occur on the surface of the ultrasonic transducer and the sound wave reflection surface, which will affect the measurement of wind speed and flow rate by the ultrasonic sensor, especially serious in the coal mine field.

[0003] In the coal mining environment, there are various dangerous gases, such as methane, ethane, hydrogen, etc. that are prone to explosion, nitrogen oxide gases, hydrogen sulfide, sulfur dioxide gases, carbon monoxide gases, etc. that are harmful to the human body, and carbon dioxide gases, methane, etc. that cause asphyxiation. In addition, there are also solid powders such as dust generated during the coal mining process. Therefore, a ventilation system is built in the mine, and the ventilation system shoulders the heavy responsibility of "the lungs of the mine", mainly delivering sufficient fresh oxygen to underground workers, diluting and removing toxic, harmful, explosive gases and dust, regulating the temperature and humidity of the underground air, improving the working environment of underground workers, and ensuring the safe production of the mine. If the mine ventilation system fails, it will have a major impact on the production and safety of the entire mining area. Therefore, it is very necessary and important to monitor the performance and state of the mine ventilation system.

[0004] In the performance monitoring of the mine ventilation system, wind speed monitoring is one of the main contents, and the mine wind speed sensor is a necessary sensor for detecting mine ventilation parameters. The mine wind speed sensor is used to detect the wind speed at various ventilation main return airways, air inlets, main underground wind measurement stations, fan wellheads, heading faces, coal mining faces, main fans, etc. in coal mines. To ensure the real-time monitoring of mine ventilation and the accuracy of monitoring parameters, currently, most ultrasonic wind speed sensors are used to measure the wind speed underground in mines. The ultrasonic wind speed sensor has two structures: direct irradiation type and reflection type. The direct irradiation type ultrasonic wind speed sensor has stronger dust adhesion resistance than the reflection type structure. However, in the high-humidity and high-dust wind field environment underground in mines, dust accumulation will also occur on the surface of the direct irradiation type ultrasonic wind speed sensor, and it still needs to be cleaned in time during actual use.

[0005] When dust accumulates on the surface of the ultrasonic transducer or the sound wave reflection surface of the ultrasonic wind speed sensor, it will affect the wind speed measurement accuracy of the sensor. In severe cases, it may even cause the ultrasonic wind speed sensor to be unable to measure the wind speed directly. However, currently, the method of regular inspection and cleaning of the sensor dust is adopted to ensure the normal operation of the sensor. Regular inspection may cause some sensors to accumulate dust excessively but cannot be cleaned in time, affecting the detection accuracy of the sensor; or some sensors have a relatively slight dust accumulation degree that does not reach the level that needs to be cleaned, but they are still cleaned, resulting in the phenomenon of excessive inspection, wasting manpower. Therefore, regular inspection cannot meet the actual needs of sensor dust cleaning. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide an intelligent recognition method for the dust accumulation state of an ultrasonic wind speed sensor, which issues a warning signal to remind relevant personnel to clean the dust in time after the dust accumulation degree of the sensor exceeds the preset threshold.

[0007] To achieve the above purpose, the present invention provides the following technical solutions:

[0008] An intelligent recognition method for the dust accumulation state of an ultrasonic wind speed sensor, which utilizes the relationship between the dust accumulation degree and the amplitude of the ultrasonic received signal, identifies the dust adhesion degree on the surface of the ultrasonic transducer or the sound wave reflection surface by detecting the change of the signal amplitude, processes the dust adhesion degree and compares it with the set threshold, and gives a warning prompt when the threshold is exceeded, specifically as follows:

[0009] After the ultrasonic transducer detects the ultrasonic signal, it is sent to the signal amplification circuit. The signal amplification circuit shapes the original signal, and then the AGC regulator amplifies the gain of the ultrasonic signal; calculates the dust adhesion degree and discretizes the dust adhesion degree, compares the discretized dust adhesion degree with the preset threshold, and judges whether a warning prompt is needed according to the comparison result.

[0010] Further, the method for calculating the dust adhesion degree is as follows: Let the gain amplification factor of the AGC (Automatic Gain Control) regulator be A AGC , the maximum amplitude of the received ultrasonic signal be A m , assuming that the ultrasonic signal has no wind, no dust adhesion and A AGC = 1, the signal amplitude is A m0 , then the dust adhesion degree ε is:

[0011]

[0012] In the formula, V represents the wind speed magnitude, and h(V) represents the compensation function of the wind speed to the ultrasonic signal amplitude.

[0013] The compensation function h(V) is specifically as follows:

[0014]

[0015] In the formula, g(·) represents the functional relationship between the attenuation rate of the ultrasonic signal sound pressure level and the ultrasonic angle offset, where the angle offset refers to the offset angle of the ultrasonic propagation direction caused by the wind speed, C represents the magnitude of the ultrasonic velocity, and θ represents the included angle between the wind speed direction and the ultrasonic inherent propagation direction.

[0016] Furthermore, the discretized dust adhesion degree is specifically as follows: The dust adhesion degree is first filtered and then discretized to obtain the discrete quantity ε(k):

[0017]

[0018] In the formula, K p represents the update coefficient of ε(k).

[0019] When the discrete quantity ε(k) is greater than the preset threshold ε th , the ultrasonic wind speed sensor gives an early warning; when the discrete quantity is less than the preset threshold ε thd , the ultrasonic wind speed sensor exits the early warning state; where ε thd <ε th .

[0020] The beneficial effects of the present invention are as follows: By establishing a dust adhesion degree calculation model, filtering and discretizing it, comparing the discrete quantity of the dust adhesion degree with the set threshold, and intelligently judging whether dust cleaning is required, the present invention can dynamically extend the inspection cycle of the ultrasonic wind speed sensor, avoid the phenomenon that the measurement accuracy of the sensor decreases or it cannot work due to the failure to clean the dust in time, and enhance the data reliability of the sensor.

[0021] Other advantages, objectives, and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0023] Figure 1 is the intelligent recognition method flow for the dust accumulation state;

[0024] Figure 2 is the ultrasonic signal detection circuit;

[0025] Figure 3 is the amplitude of the ultrasonic signal;

[0026] Figure 4 The influence of wind speed on the actual sound wave propagation direction;

[0027] Figure 5 The relationship between the sound pressure level emitted by the ultrasonic transducer and the offset angle. Specific implementation manners

[0028] The following uses specific specific examples to illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0029] Please refer to Figures 1 to 5 , which is an intelligent recognition method for the dust accumulation state of an ultrasonic wind speed sensor. The present invention discriminates the dust accumulation degree of the sensor by detecting the amplitude of the ultrasonic signal, and at the same time adopts a wind speed compensation algorithm to improve the discrimination accuracy. When the dust accumulation degree exceeds the set threshold, it is determined that the accuracy of the sensor may be affected by dust accumulation, and a warning signal is sent to remind relevant personnel to perform maintenance. The specific method of the present invention is as follows:

[0030] First, build a detection circuit for ultrasonic signals to detect signals. As Figure 2 shown, the detection circuit includes a signal amplification circuit, an AGC regulator, an AD converter, and a microcontroller. After the ultrasonic transducer detects the ultrasonic signal, it is sent to the signal amplification circuit, where the original signal is shaped (such as band-pass filtering, fixed multiple amplification, etc.), and through AGC adjustment, the signal can be linearly amplified by a specified amplification multiple within a certain range to ensure that the signal amplitude is within the optimal working range of the AD conversion chip and the distortion degree of signal sampling is minimized. The AGC regulator is controlled by the microcontroller, and its amplification multiple is A AGC , and define the maximum value of the received signal sampling value shown in Figure 3 as amplitude A m , and define the signal amplitude as A AGC under the conditions of no wind, no dust adhesion, and A m0 =1. Dust adhesion reduces the original amplitude of the signal, and the microcontroller will increase A AGC to compensate for the reduced amplitude. According to the above content, define the dust adhesion degree as:

[0031]

[0032] Wherein, V represents the wind speed magnitude, and h(V) represents the compensation function of the wind speed on the signal amplitude.

[0033] In addition to the influence of dust, the wind speed magnitude will also affect the signal amplitude. Therefore, it is necessary to filter the wind speed influence component. The ultrasonic transducer has good directivity, and its beam width (the half-power angle at which the sound pressure level drops by -3 dB) is usually less than 10°. When there is no wind, the received signal amplitude is the largest. When there is wind, the wind speed forms an angle θ with the inherent propagation direction of the ultrasonic wave as shown in Figure 4 . Then the actual acoustic wave propagation direction is . The acoustic wave angle offset caused by the wind speed is the angle β between . According to the above, the following formula can be obtained:

[0034]

[0035] Wherein, C represents the wind speed magnitude.

[0036] The sound pressure level of the signal emitted by the ultrasonic transducer shows a decreasing trend as the angle offset as shown in Figure 5 . Its functional relationship can be obtained by curve fitting or interpolation method based on experimental results or parameters provided by the manufacturer:

[0037] η = g(β) (3)

[0038] By using equations (2) and (3), the relationship formula for the attenuation effect of the wind speed on the ultrasonic signal amplitude can be obtained:

[0039]

[0040] Finally, after filtering and discretization processing of the dust adhesion degree, the following formula is obtained:

[0041]

[0042] By comparing the discrete quantity ε(k) calculated by equation (5) with the set threshold, it is judged whether to issue a warning: when ε(k) is greater than the preset threshold ε th , the ultrasonic wind speed sensor issues a warning to remind the maintenance personnel to clean the dust; after cleaning the dust, ε(k) decreases. When ε(k) is less than the set threshold ε thd (ε thd < ε th ), the ultrasonic wind speed sensor exits the warning state.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. An intelligent recognition method for the dust accumulation state of an ultrasonic wind speed sensor, characterized in that: This method utilizes the relationship between the dust accumulation degree and the amplitude of the ultrasonic received signal, identifies the dust adhesion degree on the surface of the ultrasonic transducer or the acoustic wave reflection surface by detecting the change in the signal amplitude, compares it with a set threshold after processing the dust adhesion degree, and gives a warning prompt when the threshold is exceeded. Specifically: First, shape and amplify the signal detected by the ultrasonic transducer; then calculate the dust adhesion degree and discretize the dust adhesion degree, compare the discretized dust adhesion degree with a preset threshold, and judge whether a warning prompt is needed according to the comparison result; among them, the method for calculating the dust adhesion degree is as follows: Let the gain amplification factor of the AGC regulator be A AGC , the maximum amplitude of the received ultrasonic signal is A m , assume that the ultrasonic signal has no wind, no dust adhesion and A AGC =1, the signal amplitude is A m0 , then the dust adhesion degree ε is: In the formula, V represents the wind speed, and h(V) represents the compensation function of the wind speed for the ultrasonic signal amplitude; the specific form of the compensation function h(V) is as follows: In the formula, g(·) represents the functional relationship between the attenuation rate of the ultrasonic signal sound pressure level and the ultrasonic angle offset amount, where the angle offset amount refers to the offset angle of the ultrasonic propagation direction caused by the wind speed, C represents the ultrasonic speed, and θ represents the included angle between the wind speed direction and the ultrasonic inherent propagation direction.

2. The intelligent recognition method for dust accumulation state according to claim 1, characterized in that: The discretization of the dust adhesion degree is specifically as follows: First, filter the dust adhesion degree, and then perform discretization to obtain the discrete quantity ε(k): where K p represents the update coefficient of ε(k).

3. The intelligent recognition method for dust accumulation state according to claim 2, wherein: When the discrete quantity ε(k) is greater than the preset threshold ε th , the ultrasonic wind speed sensor gives an early warning; when the discrete quantity is less than the preset threshold ε thd , the ultrasonic wind speed sensor exits the early warning state; where ε thd < ε th .

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