JP2021175963A - Wind direction/wind speed meter - Google Patents

Abstract

To provide a wind direction/wind speed meter that is hardly affected by disturbance and can improve measurement accuracy.SOLUTION: White noise is output from a speaker 110, enters a scattering plate 210, and is scattered here in a spherical direction. The scattered white noise is incident to each microphone 120E, 120W, 120S, 120N to be converted into an electric signal. In a cross-correlation function calculation unit 300, operation for obtaining a cross-correlation function is performed with respect to an output electric signal of the microphones 120E and 120W. Wind causes deviation between a time of incidence of white noise to the microphone 120E and that to the microphone 120W. Thereby, wind speed in an east-west direction is obtained. Similarly, wind speed in a north-south direction is also determined. Then, vector calculation is performed by a vector calculation unit 302 from the wind speed, and a wind direction and wind speed are obtained and displayed on a display unit 304.SELECTED DRAWING: Figure 1

Description

The present invention relates to an improvement of a wind direction / anemometer for measuring a wind direction or a wind speed.

As a conventional anemometer, for example, there is an ultrasonic type anemometer described in Patent Document 1 below. The purpose of this is to improve the accuracy. One transmission ultrasonic element and four reception ultrasonic elements are opposed to each other by the ultrasonic outlet and the ultrasonic inlet, and the incident port is Arrange them so that they are on the same surface and are orthogonal to each other in two axial directions, and provide a scattering plate. Then, four ultrasonic wave propagation times from the transmitting ultrasonic element to the four receiving ultrasonic elements via the scattering plate are detected, and the wind speed and the wind direction are calculated based on this.

Japanese Unexamined Patent Publication No. 8-220127

By the way, in the background technique described above, as a method of detecting the propagation time of ultrasonic waves,
a, Detect the phase difference of ultrasonic transmission / reception waveforms,
b, Burst oscillation of ultrasonic waves and detection of the time from burst oscillation to reception,
Although the method has been pointed out (paragraph 0021 of the specification), any method may be affected by disturbance noise, resulting in a decrease in measurement accuracy.

The present invention focuses on this point, and an object of the present invention is to provide a wind direction / anemometer that is not easily affected by disturbance and can improve measurement accuracy.

The present invention includes a speaker that outputs white noise, a scattering plate that scatters the white noise output from the speaker, a plurality of microphones that receive the white noise scattered by the scattering plate and convert it into an electric signal, and the plurality of microphones. A cross-correlation function calculation means that calculates a cross-correlation function from an electric signal output from a microphone, and at least the wind direction or velocity of the wind passing between the speaker and the scattering plate from the cross-correlation function obtained by the calculation means. It is characterized by being equipped with a vector calculation means for calculating one of them.

According to one of the main forms, the microphones are arranged in the north, south, east, and west directions at equal distances from the speaker. According to another form, the scattering plate is characterized by having a hemispherical shape. The above and other objects, features and advantages of the present invention will be clarified from the following detailed description and accompanying drawings.

According to the present invention, white noise transmitted from a speaker is received by a plurality of microphones, a cross-correlation function is obtained between the received signals of the microphones, and a vector calculation is performed from these values to obtain a wind direction and a wind speed. Therefore, it is not easily affected by external noise, and the measurement accuracy can be improved.

It is a figure which shows the arrangement of a speaker and a microphone in one Example of this invention. It is a block diagram which shows the structure of the arithmetic circuit in the said Example. It is a figure which shows an example of wind direction and wind speed measurement in the said Example. (A) shows an example of the state of wind direction and speed, (B) shows the relationship between the wind speed in the east-west direction and the delay time that gives the maximum value of the cross-correlation function, and (C) shows the relationship between the wind speed in the north-south direction and the cross-correlation function. The relationship of the delay time (lag time) that gives the maximum value of is shown. (A) and (B) are graphs showing an example of white noise in the above embodiment, and the vertical axis shows the signal strength. (C) and (D) are graphs showing an example of the cross-correlation function, and the vertical axis shows the value of the cross-correlation function. The horizontal axis of (A) to (D) indicates the delay time (lag time). (A) and (B) are graphs showing an example of white noise with external noise added in the above embodiment, and the vertical axis shows the signal strength. (C) is a graph showing an example of these cross-correlation functions, and the vertical axis shows the value of the cross-correlation function. The horizontal axis of (A) to (C) indicates the delay time (lag time).

Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

FIG. 1 shows an ultrasonic element portion of the wind direction / anemometer according to this embodiment. The figure (A) shows the state seen from a plane, and the state is shown in the figure (B) from the direction of the arrow F1.

In these figures, the ceiling 100 and the floor 200 of the device are arranged so as to be horizontal at appropriate intervals. The wind passes between the ceiling 100 and the floor 200, as shown by the arrow F1.

A speaker (ultrasonic element for oscillation) 110 is provided in the center of the ceiling 100, and around the speaker (ultrasonic element for oscillation) 110 is located at the north, south, east, and west positions on the horizontal plane and equidistant from the center of the speaker 110. , Microphones (reception ultrasonic elements) 120E, 120W, 120S, 120N, respectively. On the other hand, the floor 200 is provided with a hemispherical scattering plate 210 at a position facing the speaker 110. The ultrasonic waves output from the speaker 110 toward the floor surface 200 are reflected by the scattering plate 210 and are incident on the microphones 120E, 120W, 120S, and 120N.

FIG. 2 shows the configuration of the wind direction / speed calculation circuit. In the figure, the microphones 120E, 120W, 120S, and 120N described above convert the received ultrasonic signal into an electric signal and output it. The output electric signal is input to the cross-correlation function calculation unit 300. The cross-correlation function calculation unit 300 calculates the cross-correlation function from the input signal. The calculated value of the cross-correlation function is input to the vector calculation unit 302, where the wind direction and speed are calculated from the input signal and the calculation result is output to the display unit 304. It has become.

Of these, the cross-correlation function calculation unit 300 has a function of calculating the cross-correlation function from the electric signal output from the opposite microphone among the microphones 120E, 120W, 120S, and 120N. This calculation result corresponds to the wind speed in the east-west direction and the north-south direction. Specifically, the wind speed in the east-west direction is calculated from the electric signals of the microphones 120E and 120W, and the wind speed in the north-south direction is calculated from the electric signals of the microphones 120S and 120N. The calculated east-west direction and north-south direction wind speeds are input to the vector calculation unit 302. The vector calculation unit 302 performs vector calculation based on the wind speed in the east-west direction and the wind speed in the north-south direction, obtains the wind direction and speed, and outputs the wind direction and speed to the display unit 304. The display unit 304 displays the wind speed and the wind direction based on the input calculation result.

Next, the operation of this embodiment will be described. As described above, white noise is output from the speaker 110. The ideal white noise has the same amplitude of all frequency components, but is not always ideal in this embodiment. However, there is no problem in measuring the wind direction and speed. The white noise output from the speaker 110 enters the scattering plate 210, is reflected here, and diffuses in the spherical direction. The reflected white noise enters the microphones 120E, 120W, 120S, and 120N, respectively, and is converted into an electric signal.

The cross-correlation function calculation unit 300 performs an operation to obtain a cross-correlation function for the output electric signals of the microphones 120E and 120W. Here, assuming that no wind is blowing, the same white noise is incident on the microphones 120E and 120W in the same phase. Therefore, the calculation result of the cross-correlation function shows the wind speed "0". In this case, the calculation result of the cross-correlation function matches the autocorrelation function of white noise. If white noise is ideal, the autocorrelation function is the so-called delta function. In this embodiment, the white noise is not ideal and disturbance noise is added, so that the delta function is not ideal, but the waveforms are approximately approximate. FIG. 4 (D) shows an example of the cross-correlation function. The same applies to the output electric signals of the microphones 120S and 120N.

Next, for example, as shown in FIG. 3 (A), it is assumed that the wind is blowing from the southwest direction. In this case, due to the influence of the wind, there will be a discrepancy between the incident time of the white noise on the microphone 120E and the incident time of the white noise on the microphone 120W. In the illustrated example, the incident time on the microphone 120E is earlier than the incident time on the microphone 120W. An example of the signal waveform is shown in FIG. 4, and the waveforms of the white noise incident on the microphones 120E and 120W are shown in FIGS. (A) and (B), respectively. When these cross-correlation functions are calculated, they are shown in Fig. (C). Comparing this with the case of no wind in Fig. (D), there is a time difference of ΔT between the peaks, but since this is caused by the wind, the wind speed in the east-west direction from this time difference of ΔT. Can be sought. The same applies to the north-south direction.

FIG. 5 shows a case where disturbance noise is added to the signal waveforms of FIGS. 4A and 4B. In addition to the white noise from the speaker 110, the microphones 120E, 120W, 120S, and 120N also pick up various disturbance noises existing in the environment in which the device is installed. These disturbance noises are mixed with the white noise, and the waveforms shown in FIGS. 4A and 4B are as shown in FIGS. 5A and 5B. However, even in this case, if the cross-correlation function is obtained, the influence of disturbance noise is reduced, and the cross-correlation function is as shown in FIG. 5 (C), which is compared with FIG. 4 (C) described above. There is no deviation in the peak position. Therefore, the wind speed can be calculated well.

Fig. 3 (B) shows the relationship between the value of the cross-correlation function in the east-west direction and the wind speed, and Fig. 3 (C) shows the relationship between the value of the cross-correlation function in the north-south direction and the wind speed. There is. Each value of the velocity in the east-west direction and the velocity in the north-south direction obtained from the cross-correlation function is input to the vector calculation unit 302, and the vector calculation is performed. That is, the vector indicating the velocity in the east-west direction and the vector indicating the velocity in the north-south direction are combined to obtain a vector having a length corresponding to the wind speed and facing the wind direction (Fig. 3 (A)). reference).

In the example shown in FIG. 3 (A), the wind speed in the east-west direction is the VEW shown in the figure (B), and the wind speed in the north-south direction is the VSN shown in the figure (C). These correspond to the lengths of the vectors FEW and FSN shown in FIG. Then, when these vectors FEW and FSN are combined, it becomes a vector FK, the magnitude of this vector FK indicates the wind speed, and the direction indicates the wind direction.

The cross-correlation function and auto-cross-correlation function are described in detail in, for example, Mikio Hino's "Spectrum Analysis" (Asakura Shoten, October 1, 1977, first edition).

As described above, according to the present embodiment, the white noise ultrasonic waves transmitted from the speaker are transmitted and received by the north, south, east, and west microphones, and the cross-correlation function is obtained between the received signals of the east, west, and north and south microphones, and this value is obtained. Since the wind direction and speed are obtained by performing vector calculation from the above, it is not easily affected by external noise and the measurement accuracy can be improved.

<Other Examples> The present invention is not limited to the above-mentioned examples, and various modifications can be made without departing from the gist of the present invention. For example, the following are also included.
(1) In the above embodiment, the hemispherical scattering plate 210 is used, but if the ultrasonic waves output from the speaker 110 can be reflected toward the microphones 120E, 120W, 120S, 120N, a shape other than the hemispherical shape, for example, a square. It may be in the shape of a weight.
(2) In the above embodiment, the microphones 120E, 120W, 120S, and 120N are arranged at positions that are in the north, south, east, and west directions. There is a need to.
(3) In the above embodiment, the speaker 110 is installed on the ceiling 100 side and the microphones 120E, 120W, 120S, 120N are installed on the floor 200 side, but the reverse may be performed.
(4) In the above embodiment, the white noise of ultrasonic waves is used, but it does not have to be ultrasonic waves.
(5) In the above embodiment, four microphones in the north, south, east, and west are used, but if there are at least two microphones, the wind speed in the installation direction of those microphones can be obtained. The wind direction can be obtained by providing three microphones and performing vector operations.
(6) In the above embodiment, the wind direction and the wind speed are obtained, but only one of them may be obtained.

According to the present invention, white noise transmitted from a speaker is received by a plurality of microphones, a cross-correlation function is obtained between the received signals of the microphones, and a vector calculation is performed from these values to obtain a wind direction and a wind speed. Therefore, it is not easily affected by external noise and the measurement accuracy can be improved, which is suitable for measuring the wind direction and speed.

100: Ceiling 110: Speaker 120E, 120W, 120S, 120N: Microphone 200: Floor 210: Scattering plate 300: Cross-correlation function calculation unit 302: Vector calculation unit 304: Display unit

Claims (3)

Speaker that outputs white noise,
A scattering plate that scatters white noise output from the speaker,
A plurality of microphones that receive white noise scattered by the scattering plate and convert it into an electric signal.
Cross-correlation function calculation means for calculating a cross-correlation function from electrical signals output from the plurality of microphones,
A vector calculation means for calculating at least one of the wind direction and the wind speed of the wind passing between the speaker and the scattering plate from the cross-correlation function obtained by the calculation means.
Anemometer that features a wind direction and anemometer. The anemometer according to claim 1, wherein the microphones are arranged in the north, south, east, and west directions at equal distances from the speaker. The anemometer according to claim 1 or 2, wherein the scattering plate has a hemispherical shape.

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