WO2022082698A1

WO2022082698A1 - Correction method and apparatus for ultrasonic anemograph

Info

Publication number: WO2022082698A1
Application number: PCT/CN2020/123102
Authority: WO
Inventors: 陈志勇; 陈智; 于东亮
Original assignee: 中科传启（苏州）科技有限公司
Priority date: 2020-10-19
Filing date: 2020-10-23
Publication date: 2022-04-28
Also published as: CN112433068A; CN112433068B

Abstract

A correction method and apparatus for an ultrasonic anemograph. The correction method comprises: calculating the propagation speed C_air of an ultrasonic wave; processing a signal received in a direction from a transducer n to a transducer s, so as to obtain an arrival time t_ns₁ of a direct wave and an arrival time t_ns₂ of a primary echo; calculating a propagation time tof_ns of the ultrasonic wave and a system delay dt_ns according to t_ns₁ and t_ns₂; processing a signal received in a direction from the transducer s to the transducer n, so as to obtain an arrival time t_sn₁ of the direct wave and an arrival time t_sn₂ of the primary echo; calculating a propagation time tof_sn of the ultrasonic wave and the system delay dt_sn according to t_sn₁ and t_sn₂; and respectively calculating the distance d_ns between the transducer n and the transducer s and the distance d_sn between the transducer s and the transducer n, calculating the error Δd between the two distances d_ns and d_sn, and comparing the error Δd with a preset threshold value thd to determine the distance between the transducers and the state of a sealing cavity. According to the correction method, both the distance between transducers and a system delay can be corrected at the same time, and it can be ensured that correction is performed in a windless environment, thereby improving the correction accuracy for an ultrasonic anemograph.

Description

An ultrasonic anemometer calibration method and device

technical field

The invention relates to the field of ultrasonic anemometers, in particular to a calibration method and device for an ultrasonic anemometer.

Background technique

Wind is a natural phenomenon caused by air flow. It is closely related to human daily activities, agriculture, industry, etc., including two parameters of wind speed and wind direction. It is one of the extremely important meteorological elements. Accurate grasp of wind speed and wind direction Related to the daily production of the people, the measurement of wind speed and direction has a wide range of application requirements in the fields of meteorology, construction, highway, civil aviation, bridges, agriculture, new energy and military.

Ultrasonic anemometers are instruments that measure wind speed vectors by detecting the effect of air flow on ultrasonic pulses. The existing ultrasonic anemometer obtains the propagation time of forward and reverse flow through signal processing methods such as threshold method, correlation, peak value, etc., but it is affected by filter delay, transducer parameter difference, hardware startup time, etc., the signal processing calculation The propagation time of the ultrasonic anemometer is not equal to the actual propagation time of the sound wave, which will cause the actual measured wind speed of the ultrasonic anemometer to be not 0 at zero wind speed, which makes the zero value of the ultrasonic anemometer drift. The zero offset will seriously affect the measurement accuracy of the ultrasonic anemometer, especially when measuring low wind speeds, the ultrasonic anemometer needs to be zeroed.

The existing ultrasonic anemometer is zeroed, mainly in a wind tunnel or a special device before leaving the factory to create a windless environment, and the calibration is performed according to the distance between a pair of transceiver transducers, the ambient temperature and humidity, and the time calculated by signal processing. .

The spacing of the transceiver transducers used in the calibration is usually the size of the structure design, but due to production, transportation and other reasons, the actual size may have errors, resulting in deviations in the calibration and affecting the accuracy of the anemometer; there are also vernier calipers used to measure the transducer before calibration. The distance between the calipers is re-entered into the software for calibration. This method is complicated to operate, and the human measurement error is large. It requires skilled use of vernier calipers.

Therefore, in the zero-point calibration of the prior art, on the one hand, the spacing of the transducers is not corrected, and on the other hand, it does not verify whether the correction environment is zero wind speed, and there may be a problem of calibration deviation, which affects the accuracy of subsequent anemometer detection.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide an ultrasonic anemometer calibration method and device, which can simultaneously correct the transducer spacing and system delay, and ensure that the calibration is performed in a windless environment, thereby improving the calibration accuracy of the ultrasonic anemometer.

In order to solve the above-mentioned technical problems, the present invention proposes a calibration method for an ultrasonic anemometer, which is characterized in that it includes the following calibration steps:

Calculate the propagation velocity C _air of the ultrasonic wave in the sealed cavity;

Put the ultrasonic anemometer into the sealed cavity, and use the transducer s and the transducer n located on the same dimension to send and receive ultrasonic waves;

Process the signals received from the transducer n to the transducer s to obtain the arrival time t_ns _{1 of the direct wave and the arrival time t_ns 2} _of the primary echo;

According to the arrival time t_ns _{1 of the direct wave and the arrival time t_ns 2} _of the primary echo, the ultrasonic propagation time tof _ns and the system time delay dt _ns are obtained by calculating;

Process the signals received in the direction from transducer s to transducer n to obtain the arrival time t_sn _{1 of the direct wave and the arrival time t_sn 2} _of the primary echo;

According to the arrival time t_sn _{1 of the direct wave and the arrival time t_sn 2} _of the primary echo, the ultrasonic propagation time tof _sn and the system time delay dt _sn are obtained by calculating;

Calculate the distance d _ns from transducer n to transducer s and the distance d _sn from transducer s to transducer n respectively, calculate the error Δd between the two distances, and compare the errors The size of Δd and the preset threshold thd determines the distance between the transducers and the state of the sealed cavity.

Preferably, if the error Δd is less than the preset threshold thd, the distance between the transducers is

If the error Δd is greater than the preset threshold thd, there is still air flowing in the sealed cavity, and the calibration step needs to be repeated.

Preferably, before calculating the propagation speed C _air of the ultrasonic wave in the sealed cavity, a small fan is turned on to make the inner space of the sealed cavity thermally balanced.

Preferably, the propagation speed of the ultrasonic wave in the sealed cavity is calculated according to the reading of the temperature and humidity sensor and an empirical formula

Preferably, when processing the signal received in the direction from transducer n to transducer s, the ultrasonic propagation time

the system delay

The distance between the transducer n and the transducer s is dn _ns =tof _ns C _air .

Preferably, when processing the signal received in the direction from transducer s to transducer n, the ultrasonic propagation time

the system delay

The distance between the transducer s and the transducer n is d _sn =tof _sn C _air .

Preferably, after the calibration of a pair of transducers located in the same dimension is completed, the calibration step is repeated for a pair of transducers in other dimensions to perform calibration.

In order to solve the above technical problems, the present invention also proposes an ultrasonic anemometer calibration device, which is characterized by comprising: a sealed cavity covering the ultrasonic anemometer, a temperature and humidity sensor installed in the sealed cavity, and a temperature and humidity sensor installed in the sealed cavity. A fan in a sealed chamber.

Preferably, a plurality of casings are also included, the casings are spliced to form the sealed cavity, and a through hole for placing the ultrasonic anemometer is opened at the splicing of the casings.

Preferably, it is characterized in that sound-absorbing cotton is pasted on the inner wall of the sealed cavity.

Compared with the prior art, the present invention has the following advantages:

The ultrasonic anemometer calibration method and device of the present invention, according to the arrival time of the direct wave and the primary echo received by the transducer at zero wind speed, correct the system delay and transducer spacing at the same time, so as to avoid the production, transportation and other reasons causing the transducer Deviation occurs, thereby improving the accuracy of the anemometer, and the method ensures that the correction is performed in a windless environment by comparing the transducer spacing measured twice, and improves the accuracy of the correction operation. The operation is simple, the zero point correction accuracy is high, and it can be widely used in ultrasonic anemometers of different product grades and different dimensions.

Description of drawings

The drawings described herein are for explanatory purposes only and are not intended to limit the scope of the present disclosure in any way. In addition, the shapes and proportions of the components in the figures are only schematic and are used to help the understanding of the present invention, and do not specifically limit the shapes and proportions of the components of the present invention. Under the teachings of the present invention, those skilled in the art can select various possible shapes and proportions according to specific conditions to implement the present invention. In the attached image:

Fig. 1 is the structural representation of a kind of ultrasonic anemometer calibration device of the present invention;

Fig. 2 is the flow chart of a kind of ultrasonic anemometer calibration method of the present invention;

Fig. 3 is the schematic diagram of direct wave and primary echo in the present invention;

Fig. 4 is the envelope diagram of the received signal in the present invention;

As shown in the figure: 1. Sealed cavity; 2. Temperature and humidity sensor; 3. Fan; 4. Housing cover; 5. Via hole; 6. Ultrasonic anemometer.

Detailed ways

In order to make those skilled in the art better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described The embodiments are only some of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for the purpose of illustration only and do not represent the only embodiment.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the present invention are for the purpose of describing specific embodiments only, and are not intended to limit the present invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown in FIG. 1, an ultrasonic anemometer calibration device corresponding to a preferred embodiment of the present invention includes: a sealed cavity 1 covering the ultrasonic anemometer, a temperature and humidity sensor 2 installed in the sealed cavity 1, and The fan 3 installed in the sealed cavity 1 . Wherein, the sealed cavity 1 is formed by splicing a plurality of shells 4, and the sealed cavity 1 can be designed into any suitable space configuration as required, for example, including but not limited to a cube, a cylinder, a sphere, and the like. The splicing part of the casing 4 is provided with a through hole 5 for placing the ultrasonic anemometer, between the through hole 5 and the ultrasonic anemometer 6, and the splicing part of the casing 4 are provided with a sealing device or a wind shielding device to ensure that the joint is connected. and splicing will not affect the windless environment in the sealed cavity 1. The inner wall of the sealed cavity 1 is pasted with sound-absorbing cotton, which effectively reduces the reflection of ultrasonic waves and prevents the influence of the sound waves emitted by the ultrasonic wave itself during operation.

When calibrating, it is only necessary to install the casing 4 for the ultrasonic anemometer to be calibrated, so that the ultrasonic anemometer 6 is placed in the sealed cavity 1 through the through hole 5, and the environment where the ultrasonic anemometer 6 is located is different from The atmospheric environment is isolated to avoid the interference of the environmental changes of the atmospheric environment on the ultrasonic anemometer 6, which ensures the accuracy and precision of the ultrasonic anemometer when it is calibrated. After the calibration is completed, the casing 4 is removed, and the ultrasonic anemometer can be used normally, realizing real-time calibration, avoiding disassembly of the ultrasonic anemometer, saving time and further reducing costs.

The present embodiment also provides a method for calibrating the ultrasonic anemometer using the above-mentioned calibration device, as shown in FIG. 2 , including the following steps:

Turn on the small fan 3 to make the internal space of the sealed cavity thermally balanced to avoid uneven temperature distribution everywhere. After the small fan is turned off and the airflow is stabilized, the propagation of the ultrasonic wave in the sealed cavity is calculated according to the reading of the temperature and humidity sensor and the empirical formula. Speed C _air :

Put the ultrasonic anemometer into the sealed cavity, and use the transducer s and the transducer n located in the same dimension to send and receive ultrasonic waves. The received ultrasonic signals include direct waves and multiple echoes. The envelope of the received signal is shown in Figure 4. As shown, in the calibration method of this embodiment, the direct wave and the primary echo are selected (as shown in FIG. 3 , the straight line represents the direct wave, and the dotted line represents the primary echo).

The signal received from the transducer n to the transducer s is processed, and the arrival time t_ns ₁ of the direct wave and the time of the primary echo are calculated according to the position of the peak point of the received signal (or correlation, threshold comparison, phase, etc.). Arrival time t_ns ₂ ;

Among them, the length of the direct wave propagation path is the distance d _ns from transducer n to transducer s , the propagation time is recorded as tof _ns , and the propagation path of the primary echo is three times the distance from transducer n to transducer s The distance between them is 3d _ns , the propagation time is 3tof _ns , the difference between the actual sound propagation time and the propagation time obtained by signal processing is the system delay dt _ns , we can get,

The relationship between the arrival time t_ns ₁ of the direct wave, the ultrasonic propagation time tof _ns and the system time delay dt _ns is:

t_ns ₁ +dt _ns =tof _ns

The relationship between the arrival time t_ns ₂ of the primary echo, the ultrasonic propagation time tof _ns and the system delay dt _ns is:

t_ns ₂ +dt _ns =3tof _ns

You can get:

When processing the signal received in the direction from transducer n to transducer s, the ultrasonic wave propagation time

the system delay

Similarly, the signals received from the transducer s to the transducer n are processed to obtain the arrival time t_sn _{1 of the direct wave and the arrival time t_sn 2} _of the primary echo;

You can get:

When processing the signal received in the direction from transducer s to transducer n, the ultrasonic wave propagation time

the system delay

Calculate the distance d _ns from transducer n to transducer s and the distance d _sn from transducer s to transducer n respectively, calculate the error Δd between the two distances, and compare the errors The size of Δd and the preset threshold thd determines the distance between the transducers and the state of the sealed cavity;

Among them, the error Δd=|d _ns -d _sn |, if the error Δd is less than the preset threshold thd, the distance between the transducers is

After completing the calibration of a pair of transducers located in the same dimension, repeat the calibration steps for a pair of transducers in other dimensions to perform calibration until the paired transducers in all dimensions are calibrated.

It should be understood that the above description is for purposes of illustration and not limitation. From reading the above description, many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the preceding claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are incorporated herein by reference for the purpose of being comprehensive. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to disclaim such subject matter, nor should it be construed that the applicant has not considered such subject matter to be part of the disclosed subject matter.

Claims

An ultrasonic anemometer calibration method, characterized in that it comprises the following calibration steps:

Calculate the propagation velocity C air of the ultrasonic wave in the sealed cavity;

Put the ultrasonic anemometer into the sealed cavity, and use the transducer s and the transducer n located on the same dimension to send and receive ultrasonic waves;

Process the signals received from the transducer n to the transducer s to obtain the arrival time t_ns 1 of the direct wave and the arrival time t_ns 2 of the primary echo;

According to the arrival time t_ns 1 of the direct wave and the arrival time t_ns 2 of the primary echo, the ultrasonic propagation time tof ns and the system time delay dt ns are obtained by calculating;

Process the signals received in the direction from transducer s to transducer n to obtain the arrival time t_sn 1 of the direct wave and the arrival time t_sn 2 of the primary echo;

According to the arrival time t_sn 1 of the direct wave and the arrival time t_sn 2 of the primary echo, the ultrasonic propagation time tof sn and the system time delay dt sn are obtained by calculating;

Calculate the distance d ns from transducer n to transducer s and the distance d sn from transducer s to transducer n respectively, calculate the error Δd between the two distances, and compare the errors The size of Δd and the preset threshold thd determines the distance between the transducers and the state of the sealed cavity.
The ultrasonic anemometer calibration method according to claim 1, wherein if the error Δd is less than a preset threshold thd, the distance between the transducers is

If the error Δd is greater than the preset threshold thd, there is still air flowing in the sealed cavity, and the calibration step needs to be repeated.
The method for calibrating an ultrasonic anemometer according to claim 1, characterized in that, before calculating the propagation speed C air of ultrasonic waves in the sealed cavity, a small fan is turned on to make the internal space of the sealed cavity thermally balanced.
The ultrasonic anemometer calibration method according to claim 1, wherein the propagation speed of the ultrasonic wave in the sealed cavity is calculated according to the reading of a temperature and humidity sensor and an empirical formula
The method for calibrating an ultrasonic anemometer according to claim 1, wherein when processing the signal received in the direction from transducer n to transducer s, the ultrasonic wave propagation time
The system delay
The distance between the transducer n and the transducer s is dn ns =tof ns C air .
The method for calibrating an ultrasonic anemometer according to claim 1, wherein when processing the signal received in the direction from transducer s to transducer n, the ultrasonic wave propagation time
the system delay
The distance between the transducer s and the transducer n is d sn =tof sn C air .
The method for calibrating an ultrasonic anemometer according to claim 1, wherein after calibrating a pair of transducers located on the same dimension, repeat the calibrating step for calibrating a pair of transducers on other dimensions .
An ultrasonic anemometer calibration device is characterized in that it comprises: a sealed cavity covering the ultrasonic anemometer, a temperature and humidity sensor installed in the sealed cavity, and a fan installed in the sealed cavity.
The ultrasonic anemometer calibration device according to claim 8, further comprising a plurality of casings, the casings are spliced to form the sealed cavity, and a splicing part of the casings is provided with a place for placing the ultrasonic anemometer. vias.
The ultrasonic anemometer calibration device according to claim 8, wherein sound-absorbing cotton is pasted on the inner wall of the sealed cavity.