CN103163323B - Two-dimensional wind direction and wind speed measurement method based on temperature sensor array - Google Patents

Abstract

The invention discloses a two-dimensional wind direction and wind speed measurement method based on a temperature sensor array. The two-dimensional wind direction and wind speed measurement method based on the temperature sensor array comprises the following steps of detecting measured temperature values T1- T i corresponding to a plurality of temperature sensors (3) in windy sate and in the condition that the temperature is higher than the environment temperature delta T celsius degree (20 celsius degrees to 40 celsius degrees), wherein the plurality of temperature sensors (3) are fixed on a metal measurement piece (11) and are arranged evenly in an array mode on the circumference of an electric heating body (2) as the circle center in a circumferential direction, and obtaining the minimum temperature valve T min; determining a wind direction angle theta 0; determining wind direction according to the wind direction angle theta 0; and determining wind speed according to the T min and the maximum temperature valve T max. The wind direction and the wind speed are measured in real time according to the principles of fluid mechanics and heat loss. The measurement results are digital signals. A handling circuit is simple in structure, the size of products is small, and wind speed measurement range is large.

Description

A two-dimensional wind direction and wind speed measurement method based on temperature sensor array

technical field

The invention belongs to the technical field of wind direction and wind speed measurement, in particular to a two-dimensional wind direction and wind speed measurement method based on a temperature sensor array.

Background technique

For the measurement of wind direction and speed of air flow in free space, there are currently two-dimensional anemometers based on MEMS (Micro-Electro-Mechanical Systems, micro-electromechanical systems) technology in China, and two-dimensional wind speed meters based on CMOS (Complementary Metal Oxide Semiconductor, complementary metal oxide semiconductor) technology. Two-dimensional wind direction anemometer and two-dimensional wind direction anemometer based on ultrasonic principle.

Fig. 1 is a basic schematic diagram of a two-dimensional anemometer based on MEMS and CMOS technology, with a polysilicon heating resistor 31 in the middle, and two sets of thermopiles 32 in the periphery are perpendicular to each other and arranged symmetrically. Among them, the two-dimensional wind direction anemometer based on MEMS technology has a small range of wind speed measurement. Due to the difficulty of packaging technology for MEMS devices, a large number of MEMS devices are still in the laboratory stage and are difficult to be widely used. For the two-dimensional anemometer based on CMOS technology, the structure and form of the circuit are related to the specific working mode of the sensor. The effective output signal of the sensor is generally in the millivolt level, so it is necessary to design a processing circuit with characteristics such as low offset and low noise. Circuit design is difficult.

The other is a two-dimensional wind direction anemometer based on the ultrasonic principle. The control circuit is more complicated. The ultrasonic fluid detection instruments that have appeared in the market currently have a relatively simple structure and a large volume. High-performance products are still in the research and development stage.

Contents of the invention

The purpose of the present invention is to provide a two-dimensional wind direction and wind speed measurement method based on the temperature sensor array, which can measure the wind direction and wind speed in real time from the principles of fluid mechanics and heat loss. The measurement result is a digital signal, the processing circuit structure is simple, and the product volume is small. Wind speed measurement range is large.

The purpose of the present invention is achieved through the following technical solutions:

A two-dimensional wind direction and wind speed measurement method based on a temperature sensor array, comprising:

In the first step, the electric heating body 2 is fixed on the inner surface of the metal measuring piece 11, and a plurality of temperature sensors 3 are fixed in a circumferential array on the metal measuring piece 11 with the electric heating body 2 as the center of the circle;

In the second step, the metal measuring piece 11 is heated by the electric heating body 2 , so that the temperature of the outer surface of the metal measuring piece 11 is 20° C. to 40° C. higher than the ambient temperature.

The third step is to calculate the wind direction and wind speed:

Among them, the calculation of wind direction includes:

The metal measuring sheet 11 is placed horizontally, and the angles of the azimuth angles _θi of a plurality of temperature sensors 3 correspond to:

0, (2-1)360/i, (3-1)360/i, ..., (i-1-1)360/i and (i-1)360/i;

Obtain corresponding measured temperature values T ₁ -T _i , where i is the number of temperature sensors 3 ;

Take the minimum value T _j among the measured temperature values T ₁ ~T _i as the minimum temperature value T _min , where 1≤j≤i;

In the plane Cartesian coordinate system, the corresponding azimuth angle θ ₁ ~ θ _i angle of the circumference where each temperature sensor 3 is located is the abscissa, and the measured temperature values T ₁ ~ T _i corresponding to the temperature sensor 3 are the ordinates; for the measured temperature value T ₁ ~ T _i carry out quadratic curve fitting, and the azimuth angle corresponding to the lowest point of the curve is the wind direction angle θ ₀ for determining the wind direction;

Among them, the calculation of wind speed includes:

Fs＝(fs1+fs2+fs3+fs4)/4; unit: m/s;

In the above formula:

In the above formula:

constant;

In the above formula:

T _min , is the minimum temperature value, take the minimum value among the measured temperature values T ₁ ~T _i ; unit: °C;

T _h , is ambient temperature; unit: °C;

T _max , is the maximum temperature value; unit: °C; take the same as the measured temperature values T ₁ to T _i in the no-wind state, and its value is the maximum temperature value.

In the described method, the electric heater 2 adopts a heating resistor PTC, and the control circuit generates a pulse width modulation PWM sequence to control the temperature of the heating resistor PTC, and the method for determining the maximum temperature value T _max also includes:

T _max =0.863T _h +41.1q;

In the formula,

q is the duty cycle of the pulse width modulation PWM.

Described metal measuring piece 11 comprises the circular bottom plate of dome-shaped metal measuring piece 1; Electric heater 2 is fixed on the center of circular bottom plate; A plurality of temperature sensors 3 are evenly distributed and fixed.

The temperature sensor 3 includes at least 4, and can be arranged at most on the cylindrical side wall 12 of the metal measuring piece 1 .

The temperature sensor 3 can be packaged in SOT23-6 surface mount micro package.

It can be seen from the above-mentioned technical solution provided by the present invention that the two-dimensional wind direction and wind speed measurement method based on the temperature sensor array of the present invention measures the wind direction and wind speed in real time based on the principles of fluid mechanics and heat loss, and the measurement result is a digital signal. The processing circuit structure is simple, the product volume is small, and the wind speed measurement range is large.

Description of drawings

Fig. 1 is the structural representation of the wind direction wind speed measurement method of prior art;

Fig. 2 is the structural representation of the measurement control circuit board of the two-dimensional wind direction and wind speed measurement method based on the temperature sensor array of the present invention;

Fig. 3 is a structural schematic diagram 1 of a two-dimensional wind direction and wind speed measurement method based on a temperature sensor array according to the present invention;

Fig. 4 is the structure schematic diagram II of the two-dimensional wind direction and wind speed measurement method based on the temperature sensor array of the present invention;

Figure 5 is a structural diagram of a SOT23-6 surface mount tiny package;

Fig. 6 is a schematic diagram of quadratic curve fitting of the two-dimensional wind direction and wind speed measurement method based on the temperature sensor array according to the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Example

A two-dimensional wind direction and wind speed measurement method based on a temperature sensor array needs to make a measuring device as shown in Figure 3 and Figure 4, and the specific steps and methods include:

In the first step, the electric heating body 2 is fixed on the inner surface of the metal measuring piece 11, and a plurality of temperature sensors 3 are fixed in a circumferential array on the metal measuring piece 11 with the electric heating body 2 as the center of the circle;

In this example, as shown in Figure 3, the metal measuring piece 11 is the circular bottom plate part of the metal measuring piece 1 in the shape of a dome, and the material requires a smooth outer surface, a clean inner surface, and is not easy to rust, which can meet the requirements of welding and pasting. The thickness of the device should be very thin to facilitate heat conduction; the material itself has good thermal conductivity and a large thermal conductivity coefficient. The material is aluminum alloy, and of course other metal materials or even non-metal materials that meet the requirements can also be used.

In this example, there are 8 temperature sensors 3 , which are evenly distributed in a circumferential array and fixed on the cylindrical side wall 12 of the dome-shaped metal measuring piece 1 . Of course, in order to measure the wind direction more accurately, it is possible to adopt 12 or 16 temperature sensors 3, or even more. Of course, there are at least 4 temperature sensors 3, and the cylindrical side wall 12 of the metal measuring piece 1 can be arranged at most, so that the value of i to reach maximum. The measurement results will be more accurate. As long as the requirements for use are met, it is within the protection scope of the present invention

The temperature sensor 3 adopts SOT23-6 surface-mount tiny package. SOT23-6 is a packaging form of integrated circuits, which is small in size and suitable for surface mounting. It is a packaging method often used by integrated circuits. As shown in Figure 5, it is a typical packaging structure, which is generally provided by device manufacturers.

The electric heating body 2 adopts a heating resistor PTC. PTC (Positive Temperature Cofficient) refers to semiconductor materials or components with a large positive temperature coefficient. Positive temperature coefficient thermistor is referred to as PTC thermistor. PTC thermistor is a typical temperature-sensitive semiconductor resistor. When it exceeds a certain temperature (Curie temperature), its resistance value increases stepwise with the increase of temperature.

The invention only needs to provide 3-24V voltage to make the PTC thermistor be heated at a constant temperature. After the PTC thermistor is powered on, the self-heating temperature makes the resistance value enter the transition zone, and the heating temperature remains constant. This temperature is only related to the Curie temperature and the applied voltage of the PTC thermistor, and basically has nothing to do with the ambient temperature. Heat generation, no open flame, high conversion efficiency, long natural life and so on.

In addition, the present invention also includes a measurement control circuit board, the temperature sensor 3 and the heating resistor PTC are connected to the measurement control circuit board through wires or data lines, as shown in Figure 2, the measurement control circuit board is provided with a control circuit and a detection circuit And the output circuit, the control circuit is equipped with a single-chip microcomputer MSP430F5438A, which can control and process signals through programming. A PWM sequence is generated by the internal timer Timer_A of MSP430F5438A. The duty cycle of this PWM sequence is adjustable, and it is connected to an external power supply to control the heating temperature of the heating resistor PTC. The greater the duty cycle of the PWM sequence, the higher the heating temperature of the heating resistor PTC. The control circuit is connected to detect the results of each temperature sensor 3 through the detection circuit; the control circuit is connected to output the measurement results through the output circuit.

At the same time, it should be pointed out that in actual application, the metal measuring piece 1 is the upper cover of a tank, and the cover is placed on the tank. The measurement control circuit board and wires can be put into the tank, and only the external data lines and power cable.

The second step is to control the electric heating body 2, that is, the heating resistor PTC, to heat the metal measuring piece 11 through the measurement control circuit board, so that the temperature of the outer surface of the metal measuring piece 11 is 20° C. to 40° C. higher than the ambient temperature.

The third step, calculating wind direction and wind speed: the present invention can measure wind direction and wind speed simultaneously, wherein, calculating wind direction includes:

The metal measuring sheet 11 is placed horizontally, and the angle (unit "°") of the azimuth angle _θi of each temperature sensor 3 corresponds to:

0, (2-1)360/i, (3-1)360/i, ..., (i-1-1)360/i and (i-1)360/i;

When there is wind, the temperature values T1~Ti will vary due to heat loss. Usually a Gaussian-like distribution.

Obtain the corresponding measured temperature values T ₁ ～T _i , i is the number of temperature sensors (3); take the minimum value T _j among the measured temperature values T ₁ ～T _i as the minimum temperature value T _min , where 1≤j ≤i.

In the plane Cartesian coordinate system, the corresponding azimuth angle θ ₁ ~ θ _i angle of the circumference where each temperature sensor 3 is located is the abscissa, and the measured temperature values T ₁ ~ T _i corresponding to the temperature sensor 3 are the ordinates; for the measured temperature value T ₁ ~ T _i perform quadratic curve fitting, and the specific quadratic curve fitting process includes:

The first step, data optimization processing

Find the point D _j corresponding to the minimum temperature value T _j : Due to the principles of fluid mechanics and heat loss, the measured temperature values of other points are distributed approximately symmetrically with the minimum temperature value T _j in the order of 1~i cycle, because When the wind direction is not directly facing a certain temperature sensor 3, but blows between two temperature sensors 3, the data points are not completely symmetrically distributed with the minimum temperature value T _j , so they are approximately symmetrically distributed, but this method will not be affected The implementation of the data optimization process is specifically to arrange D ₁ ~ D _i in the order of approximately symmetrical distribution of D _j :

If i is an even number:

D _j-[i/2]+1 ,..., D _j-1 , D _j , D _j+1 ,..., D _j+[i/2] ;

If the value of j-[i/2]+1 is less than 1, use D _{i-(j-[i/2]+1)} to replace the corresponding point;

If the value of j+[i/2] is greater than i, use D _j+[i/2]-i to replace the corresponding point;

Specifically, take 8 temperature sensors 3 as an example:

If T ₂ is the minimum temperature value, the sequence is:

T ₇ , T ₈ , T ₁ , T ₂ , T ₃ , T ₄ , T ₅ , T ₆ ;

If T ₅ is the minimum temperature value, the sequence is:

T ₂ , T ₃ , T ₄ , T ₅ , T ₆ , T ₇ , T ₈ , T ₁ ;

If i is odd:

D _j-[i/2] ,..., D _j-1 , D _j , D _j+1 ,..., D _j+[i/2] ;

If the value of j-[i/2] is less than 1, use D _i-(j-[i/2]) to replace the corresponding point;

If the value of j+[i/2] is greater than i, use D _j+[i/2]-i to replace the corresponding point;

Specifically, take nine temperature sensors 3 as an example:

If T ₃ is the minimum temperature value, the sequence is:

T ₈ , T ₉ , T ₁ , T ₂ , T ₃ , T ₄ , T ₅ , T ₆ , T ₇ ;

If T ₆ is the minimum temperature value, the sequence is:

T ₂ , T ₃ , T ₄ , T ₅ , T ₆ , T ₇ , T ₈ , T ₉ , T ₁ ;

The […] above is rounding operation.

The second step, quadratic curve fitting

In the planar Cartesian coordinate system XOY, T ₁ ~ T _i arranged in the order of approximately symmetrical distribution of D _j after the optimization process is subjected to quadratic curve fitting.

Determine the wind direction

The azimuth angle corresponding to the lowest point of the curve is the wind direction angle θ ₀ for determining the wind direction; specifically, the serial number of the abscissa in the coordinate system is converted into the corresponding angle according to the abscissa x of the corresponding point D _i in Table 1, and then by The lowest point on the curve is between which two corresponding points to determine the wind direction angle θ ₀ . The wind direction can be determined according to the wind direction angle θ ₀ .

Table 1

D _i D _{1 D2 D3} … D _i-1 D _i x 1 2 3 … i-1 i _θi 0 (2-1) 360/i (3-1)360/i … (i-1-1)360/i (i-1)360/i

For example: the minimum value among the measured temperature values T ₁ ~ T ₈ is the minimum temperature value T ₇ , from the principle of heat loss, it can be known that the rest of the measured temperature values are distributed symmetrically with T ₇ , by sorting T ₁ ~ T ₈ , a model can be formed Combined 8 data points:

T ₄ , T ₅ , T ₆ , T ₇ , T ₈ , T ₁ , T ₂ , T ₃ ;

The points on the broken line as shown in Figure 6 are then fitted with a quadratic curve. The curve is a continuous curve obtained by fitting, and the azimuth corresponding to the lowest point of the fitted curve is the required wind direction angle θ ₀ .

The temperature values _T1 -T8 measured by temperature sensors _1-8 are shown in Table 2:

Table 2

It can be seen from the data that the minimum value T _j = T ₇ , other data are approximately symmetrically distributed around T ₇ , and T ₁ to T ₈ are sorted, as shown in the points on the broken line in Figure 6 . The fitting curve is shown in the curve in Figure 6, and the angle corresponding to the lowest point of the fitting curve is the wind direction angle θ ₀ . From this set of data, the lowest point of the fitting curve is located between T ₇ and T ₈ , and the corresponding wind direction angle θ ₀ is about 294°, so the obtained wind direction increases by about 294° based on the direction of 0°.

The wind direction can be determined according to the wind direction angle θ ₀ , specifically as i is 8; as the wind direction angle θ ₀ is 90 °, if the direction corresponding to 0 degrees is east, and the orientations of the temperature sensors 3 are arranged counterclockwise, then the 90 ° direction is In the north, the wind direction is "north wind". For example, the azimuths of the temperature sensors 3 are arranged clockwise, then the 90° direction is south, and the wind direction is "south wind".

Among them, the calculation of wind speed includes:

In the process of calculating the wind direction, we have obtained the minimum temperature value T _min among the measured temperature values T ₁ ~T _i , and the wind speed Fs can be calculated from the minimum temperature value T _min :

Fs＝(fs1+fs2+fs3+fs4)/4; unit: m/s;

In the above formula:

In the above formula:

constant;

In the above formula:

T _min , is the minimum temperature value; unit: ℃

T _h , is ambient temperature; unit: °C

T _max , is the maximum temperature value; unit: °C.

Here the maximum temperature value T _max needs to be determined:

Take the measured temperature value under the condition of no wind, at this time T ₁ ~ T _i are the same, and its value is the maximum temperature value. In the case of no wind, the temperature values T1 to Ti are equal and are the maximum value T _max , which is actually the heating temperature of the fixed electric heating body 2 .

Another way to determine the maximum temperature value T _max :

The electric heater 2 adopts a heating resistor PTC, and the control circuit generates a pulse width modulation PWM sequence to control the temperature of the heating resistor PTC, and the method for determining the maximum temperature value _Tmax includes:

T _max =0.863T _h +41.1q;

In the formula,

q is the duty cycle of the pulse width modulation PWM.

The principle of the present invention is generally speaking that when there is no wind flowing through the surface of the metal measuring sheet 11, because of the symmetrical layout of the temperature sensors, its temperature will also be symmetrically distributed; when the laminar air with a wind speed of Fs flows in a certain direction When passing through the surface of the metal measuring piece 11, the wind will carry away part of the heat and form a thinner thermal boundary layer on the surface, so the temperature of the sensor will be in a certain gradient distribution, and the wind direction can be calculated according to the gradient distribution; according to the thin layer According to the boundary layer theory, convective heat transfer is proportional to the square root of the flow velocity, and the wind velocity can be calculated on the basis of the wind direction.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention.

Claims (6)

1. A two-dimensional wind direction and wind speed measurement method based on temperature sensor array, it is characterized in that, comprising: The first step is to fix a circular electric heating body (2) on the inner surface of the metal measuring piece (11), and the circumferential array is evenly distributed on the metal measuring piece (11) with the electric heating body (2) as the center of the circle. Fixing multiple temperature sensors (3); The second step is to heat the metal measuring piece (11) through the electric heating body (2), so that the temperature of the outer surface of the metal measuring piece (11) is higher than the ambient temperature ΔT°C; The third step is to calculate the wind direction and wind speed: Among them, the calculation of wind direction includes: The metal measuring sheet (11) is placed horizontally, and the angles of the azimuth angles _θi of a plurality of temperature sensors (3) correspond to: 0, (2-1)360/i, (3-1)360/i, ..., (i-1-1)360/i and (i-1)360/i; Obtain corresponding measured temperature values T ₁ -T _i , where i is the number of temperature sensors (3); Take the minimum value T _j among the measured temperature values T ₁ ~T _i as the minimum temperature value T _min , where 1≤j≤i; In the planar Cartesian coordinate system, the corresponding azimuth angle θ ₁ ~ θ _i angle of the circumference where each temperature sensor (3) is located is the abscissa, and the measured temperature value T ₁ ~ T _i corresponding to the temperature sensor (3) is the ordinate; Carry out quadratic curve fitting on the measured temperature values T ₁ ~T _i , and the azimuth angle corresponding to the lowest point of the curve is the wind direction angle θ ₀ for determining the wind direction; Among them, the calculation of wind speed includes: Fs＝(fs1+fs2+fs3+fs4)/4; unit: m/s; In the above formula: In the above formula: constant; In the above formula: T _min , is the minimum temperature value; unit: ℃; T _h , is ambient temperature; unit: °C; T _max , is the maximum temperature value; unit: °C; take the same as the measured temperature values T ₁ to T _i in the no-wind state, and its value is the maximum temperature value. 2. The two-dimensional wind direction and wind speed measurement method based on the temperature sensor array according to claim 1, characterized in that the temperature of the outer surface of the heated metal measuring piece (11) is 20° C. to 40° C. higher than the ambient temperature. 3. The two-dimensional wind direction and wind speed measurement method based on the temperature sensor array according to claim 1, characterized in that, the electric heating body (2) adopts a circular heating resistor PTC, and a pulse width modulation PWM sequence is generated by a control circuit The method for controlling the temperature of the heating resistor PTC and determining the maximum temperature value T _max also includes: T _max =0.863T _h +41.1q; In the formula, q is the duty cycle of the pulse width modulation PWM. 4. The two-dimensional wind direction and wind speed measurement method based on the temperature sensor array according to claim 1, 2 or 3, characterized in that, the metal measuring piece (11) comprises a dome-shaped metal measuring piece (1) A circular bottom plate; an electric heating body (2) is fixed at the center of the circular bottom plate; a plurality of temperature sensors (3) are uniformly distributed and fixed on the cylindrical side wall (12) of the dome-shaped metal measuring piece (1) in the circumferential direction. 5. The two-dimensional wind direction and wind speed measurement method based on the temperature sensor array according to claim 1, 2 or 3, characterized in that, said temperature sensor (3) comprises at least 4, and can be filled with metal measuring pieces ( 1) The cylindrical side wall (12). 6. The method for measuring two-dimensional wind direction and wind speed based on a temperature sensor array according to claim 1, 2 or 3, characterized in that the temperature sensor (3) can be packaged in a SOT23-6 surface mount micro package.