CN110470860A - A kind of time difference method ultrasonic wind velocity indicator and calibration method - Google Patents

Abstract

The invention discloses a time-difference method ultrasonic anemometer and a calibration method, belonging to the technical field of wind speed measurement. The transit-time ultrasonic anemometer mainly includes a connection block, a U-shaped tube, an ultrasonic transceiver sensor, a support tube, an electronic north guide, a data processor, and a deflection angle sensor; the data processor is composed of a storage system, a data calibration system, and a communication system. . Based on the vector nature of the wind speed, the present invention calculates the corresponding rotation matrix by collecting the Euler angles between the three coordinate axes of the measurement coordinate system and the standard coordinate system, and completes the transformation of the same vector between different coordinate systems, realizing the Purpose of anemometer calibration. The invention does not need to perform calibration operations such as wiring and leveling of the ultrasonic anemometer, simplifies the steps of erecting the anemometer, improves the installation efficiency of the instrument, and not only solves the problems of high installation requirements and difficult calibration of the anemometer, but also ensures The authenticity and accuracy of the measured data.

Description

A time-difference ultrasonic anemometer and its calibration method

technical field

The invention belongs to the technical field of wind speed measurement, and in particular relates to a transit-time ultrasonic anemometer and a calibration method.

Background technique

Anemometer is an instrument for measuring air velocity, which is widely used in meteorology, civil engineering, agriculture, electric power, steel, petrochemical and other industries. The most widely used is the mechanical anemometer, that is, the wind cup anemometer, which calculates the wind speed based on the number of turns of the wind cup per second. It has a simple structure and has a complete theoretical basis and measurement algorithm. Because the influence of friction loss in the measurement process cannot be ignored, it often leads to large errors in the calculation results. Therefore, a variety of new anemometers have emerged, such as hot-wire anemometers, pitot tube anemometers, ultrasonic anemometers, laser Doppler anemometers, etc. Among them, ultrasonic anemometers are small in size, high in precision, wide in range, small in blind area, and well-crafted. Simple, easy to produce and other advantages, more and more users of all ages.

The ultrasonic anemometer can be divided into according to its measurement method: time difference method ultrasonic anemometer, frequency difference method ultrasonic anemometer, Doppler method ultrasonic anemometer and so on. The ultrasonic anemometer of the time difference method uses the principle that the propagation speed of sound waves in the air changes with the wind speed, and calculates the flow velocity of the air from the difference between the downwind propagation time and the headwind propagation time; the frequency difference method ultrasonic anemometer is based on the Karman According to the vortex street theory, the sound wave passing through the air will form a Karman vortex street. Under certain conditions, the vortex frequency is proportional to the air velocity, and the air velocity is measured by detecting the vortex frequency; the Doppler ultrasonic anemometer is Utilizing the characteristic that Doppler shift will occur when ultrasonic waves encounter obstacles, the air velocity is calculated by the difference between the ultrasonic frequencies at the transmitting and receiving ends. Among them, the time-difference ultrasonic anemometer has a simple principle, is easy to implement, and has a wide range of applications, and is most widely used in practice.

At present, ultrasonic anemometers of time difference method often need to cooperate with the acquisition instrument to realize data storage and transmission. Due to the difference in wire specifications between the two instruments, the wiring work becomes very complicated. If the wiring is wrong, it may cause data loss, transmission interruption, etc. . In addition, the anemometer sometimes needs to be installed on towering structures, long-span bridges and other structures through brackets. In order to ensure the accuracy of the measured data, the anemometer should be calibrated for leveling and pointing north. Safety and other factors make it difficult to calibrate the anemometer. Therefore, how to provide a new type of anemometer and a simple and efficient calibration method is a problem to be solved.

Contents of the invention

In order to solve the above problems, the present invention discloses a time-of-flight ultrasonic anemometer and a calibration method. By arranging a data processor in the anemometer, it has the functions of data collection, storage, processing and transmission. The essence of the leveling and northing calibration of the anemometer is the transformation of the coordinate system. This calibration method uses the characteristic that the wind speed is a vector, and completes the calibration by measuring the Euler angle between the coordinate system and the standard coordinate system and calculating the rotation matrix. The coordinate transformation of wind speed between the two coordinate systems realizes the leveling and northing calibration of the anemometer.

To achieve the above object, the technical scheme of the present invention is as follows:

A time-difference ultrasonic anemometer and calibration method, comprising a connection block, a U-shaped pipe, a fixed pipe, an ultrasonic transceiver sensor, a connection pipe, a support pipe, an electronic norther, a data processor, and a deflection sensor; the connection block is The cylindrical block is divided into an upper connection block and a lower connection block, which are arranged symmetrically up and down. The number of the U-shaped tubes is 4, which are arranged circumferentially outside the upper and lower connection blocks. connection, the number of fixed pipes is 6, of which 4 are fixed on the inner side of the middle of the U-shaped pipe, and the remaining 2 are respectively fixed on the lower bottom surface of the upper connection block and the upper top surface of the lower connection block, and the two fixed pipes are symmetrical Set, and the connection lines are perpendicular to each other, and each fixed pipe end is equipped with an ultrasonic transceiver sensor, a total of 6, forming 3 groups of two symmetrical ultrasonic transceiver sensors, and the distance between the two ultrasonic transceiver sensors in each group is equal , 3 of the 6 ultrasonic sensors are positioning sensors, which are the front sensor, the right sensor and the upper sensor respectively. The north pointers are arranged in the support tube for collecting the Euler angle between the measurement coordinate system and the standard coordinate system; the data processor includes a storage system, a data calibration system, and a communication system, which are also located in the support tube; the above-mentioned storage system It is used to store wind characteristic data, the data calibration system is used to calculate wind speed and calibration data, and the communication system transmits the collected data to the PC of the surveyor.

A kind of calibration method based on above-mentioned transit-time-difference method ultrasonic anemometer comprises the following steps:

Step 1: Set up the anemometer bracket at the position to be tested, and install and fix the ultrasonic anemometer on the anemometer bracket;

Step 2: Power the ultrasonic anemometer, measure the propagation time T _x , T _x ′, T _y , T _y ′, T _z , T _z ′ of ultrasonic waves between two symmetrical ultrasonic transceiver sensors, deflection angle sensor, electronic The norther collects the Euler angles α, β, and γ between the three coordinate axes of the survey coordinate system and the standard coordinate system respectively;

Step 3: The storage system stores T _x , T _x ′, T _y , T _y ′, T _z , T _z ′, α, β, γ data;

Step 4: The data processor calculates the wind speed V _x , V _y , V _z between the three groups of ultrasonic transceiver sensors in the measurement coordinate system, and forms a velocity matrix V=[V _x V _y V _z ];

Step 5: The data processor calculates the rotation matrices R _x , R _y , and R _z according to the Euler angles α, β, and γ;

Step 6: The data processor calibrates the velocity matrix V according to the rotation matrices R _x , R _y , and R _z , and obtains the calibration velocity matrix V′=[V′ _x V′ _y V′ _z ] in the standard coordinate system, and then obtains the standard Three-way wind speed V _x ′, V _y ′, V _z ′ in the coordinate system;

Step 7: Perform vector calculation on the three-way wind speed in the standard coordinate system to obtain the vector wind speed

Furthermore, the direction in which the front sensor receives ultrasonic waves is the front direction, the direction in which the right sensor receives ultrasonic waves is the right direction, and the direction in which the upper sensor receives ultrasonic waves is the upward direction; The three-dimensional Cartesian coordinate system established in the positive direction of the axis, the above-mentioned standard coordinate system is a three-dimensional Cartesian coordinate system established with the positive direction of the x' axis, the y' axis, and the vertical upward direction respectively. .

Further, the above-mentioned Euler angles α, β, and γ are the rotation angles between x—x′, y—y′, and z—z′ respectively. According to the right-hand rule, the thumb points to the positive direction of the axis, and the four fingers rotate in the direction of rotation. is the positive direction of the Euler angles.

The beneficial effects of the present invention are:

The time-difference method ultrasonic anemometer and calibration method of the present invention, by arranging a data processor in the anemometer, it has the functions of data collection, storage, processing and transmission, and at the same time utilizes the vector nature of the wind speed, by collecting two The Euler angle between the coordinate axes of the coordinate system calculates the rotation matrix, and realizes the transformation of the wind speed from the measurement coordinate system to the standard coordinate system. This calibration method is simple and efficient, without the need for wiring and leveling calibration of the ultrasonic anemometer. After the instrument is installed, the data can be directly measured and stored, which simplifies the installation steps of the anemometer and improves the installation efficiency of the instrument. It not only solves the problems of high installation requirements and difficult calibration of the anemometer, but also ensures the authenticity and rigor of the measured data.

Description of drawings

Fig. 1 is the structural representation of time-difference method ultrasonic anemometer of the present invention;

Fig. 2 is the flow chart of the calibrating method of the transit-time ultrasonic anemometer of the present invention;

Fig. 3 is a schematic diagram of the measurement coordinate system and the standard coordinate system of the calibration method of the transit-time ultrasonic anemometer of the present invention.

List of reference signs:

1. Connection block, 2. U-shaped tube, 3. Fixed tube, 4. Ultrasonic transceiver sensor, 5. Front sensor, 6. Right sensor, 7. Upper sensor, 8. Connecting tube, 9. Support tube, 10. Electronics North compass, 11. data processor, 12. deflection angle sensor.

Detailed ways

The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

As shown in Figure 1, a time-of-flight ultrasonic anemometer described in this embodiment includes a connecting block 1, a U-shaped tube 2, a fixed tube 3, an ultrasonic transceiver sensor 4, a connecting tube 8, a supporting tube 9, an electronic guide Device 10, data processor 11, deflection angle sensor 12; connecting block 1 is a cylindrical block, a total of 2 pieces, divided into upper connecting block and lower connecting block, symmetrically arranged up and down, U-shaped pipe 2 is arranged circumferentially on the upper and lower connection There are 4 pieces around the block 1, both ends of the U-shaped tube 2 are connected with the upper and lower connecting blocks 1, and there are 6 fixed tubes 3, 4 of which are fixed in the middle of the U-shaped tube 2, and the remaining 2 are respectively fixed on the upper and lower connection blocks. The lower bottom surface and the upper top surface of the block 1 are symmetrical in pairs of fixed tubes 3, and their connections are perpendicular to each other. An ultrasonic transceiver sensor 4 is installed at the end of each fixed tube 3, a total of 6, forming 3 groups of paired symmetrical The distance between two symmetrical ultrasonic transceiver sensors 4 in each group is equal, and 3 of the 6 ultrasonic transceiver sensors 4 are positioning sensors, which are respectively the front sensor 5, the right sensor 6 and the upper sensor 7, The upper part of the connecting pipe 8 is connected with the lower connecting block 1, and the lower part is connected with the support pipe 9. The deflection sensor 12 and the electronic norther 10 are all arranged in the support pipe 9, and are used to collect the ohms between the measurement coordinate system and the standard coordinate system. The data processor 11 includes a storage system, a data calibration system, and a communication system, and is also located in the support pipe 9; the storage system is used to store wind characteristic data, and the data calibration system is used to calculate wind speed and calibration data, and the communication system will collect The data is transmitted to the PC of the surveyor.

A calibration method based on the above-mentioned time-difference method ultrasonic anemometer, its flow chart as shown in Figure 2, also includes the following steps:

Step 1: Set up the anemometer bracket at the position to be tested, and fix the ultrasonic anemometer on the anemometer bracket. There is no need to perform leveling and north-pointing calibration operations, but it is not suitable to make the anemometer deflect too much;

Step 2: Supply power to the ultrasonic anemometer, and the instrument automatically measures the propagation time T _x , T _x ′, T _y , T _y ′, T _z , T _z ′ of the ultrasonic wave between two symmetrical ultrasonic transceiver sensors 4, and the deflection angle The sensor 12 and the electronic compass 10 respectively collect the Euler angles α, β, and γ of the measurement coordinate system x-axis, y-axis, z-axis and the standard coordinate system x' axis, y' axis, and z'axis;

Step 3: The storage system stores T _x , T _x ′, T _y , T _y ′, T _z , T _z ′, α, β, γ data;

Step 4: The data processor 11 calculates the wind speed V _x , V _y , V _z among the three groups of ultrasonic transceiver sensors 4, and forms a velocity matrix V=[V _x V _y V _z ];

When the distance between any two symmetrical ultrasonic transceiver sensors 4 is l (m), the wind speeds V _x , V _y , and V _z of the x-axis, y-axis, and z-axis in the measurement coordinate system as shown in Figure 3 can be obtained:

In the formula:

T _x is the time (s) for the ultrasonic wave from the x-axis negative ultrasonic transceiver sensor to the x-axis positive ultrasonic transceiver sensor in the measurement coordinate system,

T _x ′ is the time (s) for the ultrasonic wave to go from the x-axis positive ultrasonic transceiver sensor to the x-axis negative ultrasonic transceiver sensor in the measurement coordinate system,

T _y is the time (s) for the ultrasonic wave to go from the y-axis negative ultrasonic transceiver sensor to the y-axis positive ultrasonic transceiver sensor in the measurement coordinate system,

T _y ′ is the time (s) for the ultrasonic wave to go from the y-axis positive ultrasonic transceiver sensor to the y-axis negative ultrasonic transceiver sensor in the measurement coordinate system,

T _z is the time (s) for the ultrasonic wave to travel from the z-axis negative ultrasonic transceiver sensor to the z-axis positive ultrasonic transceiver sensor in the measurement coordinate system,

T _z ' is the time (s) for the ultrasonic wave to travel from the z-axis positive ultrasonic transceiver sensor to the z-axis negative ultrasonic transceiver sensor in the measurement coordinate system;

The velocity matrix V in the measurement coordinate system can be obtained from formulas (1), (2) and (3):

V＝[V _x V _y V _z ] (4)

Step 5: The data processor 9 calculates the rotation matrices R _x , R _y , R _z according to the Euler angles α, β, γ;

The essence of the calibration work for the leveling and northing of the anemometer is the transformation of the coordinate system. Transform the velocity matrix V from the measurement coordinate system to the standard coordinate system to obtain the calibration velocity matrix V′, which realizes the calibration of the anemometer. The matrix in the process of coordinate transformation is called a rotation matrix. According to the Euler angles measured by the electronic compass 10 and the declination sensor 12, the rotation matrix R _x around the x-axis can be calculated respectively:

Rotation matrix R _y around the y-axis:

Rotation matrix R _z around the z axis:

In the formula:

α is the rotation angle (°) from the measurement coordinate system x-axis to the standard coordinate system axis x′,

β is the rotation angle (°) from the measurement coordinate system y-axis to the standard coordinate system axis y′,

γ is the rotation angle (°) from the measurement coordinate system z-axis to the standard coordinate system axis z′,

According to the right-hand rule, the thumb points to the positive direction of the axis, and the rotation direction of the four fingers is the positive direction of the above-mentioned rotation angle;

Step 6: The data processor 11 calibrates the velocity matrix V according to the rotation matrices R _x , R _y , and R _z to obtain the calibrated velocity matrix V'=[V' _x V' _y V' _z ], and then obtain the Indicates the three-way wind speed V _x ′, V _y ′, V _z ′ in the standard coordinate system;

Matrix multiplication of equations (4), (5), (6), and (7) can obtain the calibration velocity matrix V′:

Thus, the wind speed V _x ′, V _y ′, V _z ′ along the x′ axis, y′ axis, and z′ axis in the standard coordinate system can be written:

V _x ′＝V _x cosβcosγ+V _y (sinαsinβcosγ-cosαsinγ)+V _z (cosαsinβcosγ+sinαsinγ) (9)

V _y ′＝V _x cosβcosγ+V _y (sinαsinβsinγ+cosαcosγ)+V _z (cosαsinβsinγ-sinαcosγ) (10)

V _z ′＝-V _x sinβ+V _y sinαcosβ+V _z cosαcosβ (11)

In the formula:

V _x ′ is the wind speed along the x-axis in the standard coordinate system (m/s),

V _y ′ is the wind speed along the x-axis in the standard coordinate system (m/s),

V _z ′ is the wind speed along the x-axis in the standard coordinate system (m/s);

Step 7: Perform vector calculation on the three-way wind speed in the standard coordinate system to obtain the vector wind speed

The magnitude of the vector wind speed can be calculated from formulas (9), (10) and (11)

The ultrasonic direction received by the front sensor 5 is the front direction, the ultrasonic direction received by the right sensor 6 is the right direction, and the ultrasonic direction received by the upper sensor 7 is the upward direction; as shown in Figure 3, the front, right and upper directions are respectively The three-dimensional Cartesian coordinate system established for the positive directions of the x-axis, y-axis, and z-axis is the measurement coordinate system, and the true north, true east, and vertical upward directions are respectively established as the positive directions of the x' axis, y' axis, and z' axis The three-dimensional Cartesian coordinate system is the standard coordinate system.

The technical means disclosed in the solutions of the present invention are not limited to the technical means disclosed in the above embodiments, but also include technical solutions composed of any combination of the above technical features.

Claims (4)

1. a time-difference method ultrasonic anemometer, it is characterized in that: comprise connection block (1), U-shaped pipe (2), fixed pipe (3), ultrasonic transceiver sensor (4), connecting pipe (8), support pipe ( 9), electronic compass (10), data processor (11), deflection sensor (12); the connecting block (1) is a cylindrical block, a total of 2 pieces, divided into upper connecting block and lower connecting block block, arranged symmetrically up and down, the number of the U-shaped tubes (2) is 4, arranged circumferentially outside the upper and lower connecting blocks (1), and the two ends of the U-shaped tubes (2) are respectively connected with the upper and lower connecting blocks (1) , the number of the fixed pipes (3) is 6, 4 of which are fixed on the inner side of the middle part of the U-shaped pipe (2), and the remaining 2 are respectively fixed on the lower bottom surface of the upper connection block and the upper top surface of the lower connection block, The fixed tubes (3) are symmetrical in pairs, and the lines between them are perpendicular to each other. An ultrasonic transceiver sensor (4) is installed at the end of each fixed tube (3), a total of 6, forming 3 groups of ultrasonic transceiver sensors that are symmetrical in pairs (3), the distance between the 2 ultrasonic transceiving sensors (4) in each group is equal, and 3 of the 6 ultrasonic sensors (4) are positioning sensors, which are respectively the front sensor (5) and the right sensor (6) and the upper sensor (7), the upper part of the connecting pipe (8) is connected with the lower connecting block (1), and the lower part is connected with the support pipe (9), and the deflection sensor (12) and the electronic north pointer (10) are both Arranged in the support tube (9), the data processor (11) includes a storage system, a data calibration system, and a communication system, and is also located in the support tube (9). 2. A calibration method based on the transit-time method ultrasonic anemometer according to claim 1, characterized in that: comprising the following steps: Step 1: Set up the anemometer bracket at the position to be tested, and install and fix the ultrasonic anemometer on the anemometer bracket; Step 2: Power the ultrasonic anemometer, measure the propagation time T _x , T _x ′, T _y , T _y ′, T _z , T _z ′ of the ultrasonic wave between the two facing ultrasonic transceiver sensors (4), and the deviation The angle sensor (12) and the electronic compass (10) respectively collect the Euler angles α, β, and γ between the three coordinate axes of the measurement coordinate system and the standard coordinate system; Step 3: The storage system stores T _x , T _x ′, T _y , T _y ′, T _z , T _z ′, α, β, γ data; Step 4: the data processor (11) calculates the wind speed V _x , V _y , V _z among the three groups of ultrasonic transceiver sensors (4) in the measurement coordinate system, and forms a velocity matrix V=[V _x V _y V _z ]; Step 5: the data processor (11) calculates the rotation matrices R _x , R _y , and R _z according to the Euler angles α, β, and γ; Step 6: the data processor (11) calibrates the velocity matrix V according to the rotation matrices R _x , R _y , and R _z to obtain the calibration velocity matrix V'=[V' _x V' _y V' _z ] in the standard coordinate system, Then get the three-way wind speed V _x ′, V _y ′, V _z ′ in the standard coordinate system; Step 7: Perform vector calculation on the three-way wind speed in the standard coordinate system to obtain the vector wind speed 3. a kind of time difference method ultrasonic anemometer calibration method according to claim 2, it is characterized in that: front sensor (5) receives ultrasonic direction and is front direction, right sensor (6) receives ultrasonic direction and is right direction, upper sensor ( 7) The direction of receiving ultrasonic waves is the upward direction; the measurement coordinate system is a three-dimensional Cartesian coordinate system established in the positive direction of the x-axis, y-axis and z-axis respectively in the front, right and upward directions; the standard coordinate system is based on the positive direction The north, due east and vertical upward directions are respectively the three-dimensional Cartesian coordinate system established in the positive direction of the x' axis, y' axis and z' axis. 4. A method for calibrating a time-of-flight ultrasonic anemometer according to claim 2, characterized in that: said Euler angles α, β, and γ are respectively x-x', y-y', z-z' According to the right-hand rule, the thumb points to the positive direction of the axis, and the rotation direction of the four fingers is the positive direction of the Euler angle.