JP7054507B2 - Measuring device, mobile body, and measuring method - Google Patents

Description

The present invention relates to a measuring device, a moving body, and a measuring method.

Operational opportunities for small unmanned aerial vehicles (eg, drones) are increasing. For example, it is expected to be used for transportation, disaster information collection, inspection of structures and equipment, etc. However, since the drone is lightweight, there is a concern that the attitude of the aircraft is likely to be disturbed by the wind, and that human errors such as maneuvering mistakes are likely to be duplicated. Therefore, robustness is required in adverse environments such as strong winds and gusts.

For those mainly targeting large aircraft, it is being considered to use the prior information obtained from the wind speed remote measurement sensor for control. For example, as a method for remote measurement of wind speed, a technique for measuring wind speed by emitting laser light and analyzing scattered light reflected by an aerosol in the air (for example, Non-cited Documents 1 and 2) and sound waves are used. Disclosed are techniques for measuring wind direction and wind speed by analyzing the scattering of sound waves reflected on discontinuous surfaces having different densities in the air (for example, Non-cited Documents 3 and 4).

Product introduction of Doppler Lidar Galleon (Japan Meteorological Co., Ltd.) https://n-kishou.com/offshorewind/galionlidar.html High altitude flight demonstration of aircraft-mounted Doppler lidar, Proceedings of the Japan Society for Aeronautics and Astronautics Vol. 62 (2014) No. 6 p. 198-203 Wind speed vertical distribution measuring device (Doppler sodar) FAS series (Eiko Seiki Co., Ltd.) http://eko.co.jp/windpower/win_products/0322.html Wind condition prediction by correlation method using mini Doppler soda, Proceedings of the 20th Wind Engineering Symposium, 2008

However, the techniques described in Non-Patent Documents 1 to 4 described above are mainly intended for large aircraft, and are difficult to mount on a drone due to the large size, weight, and power consumption of the device. In addition, the drone may fly near (near) the structure, but since the wind tends to change rapidly around the structure, it is important to estimate the wind information in advance. However, in the prior art, the level of the reflected light or the reflected wave from the structure or the like is higher than the scattering of the laser light or the sound wave, and there is a possibility that accurate measurement cannot be performed.

The present invention has been made in view of the above circumstances, and one of the objects of the present invention is to provide a measuring device, a moving body, and a measuring method capable of measuring information on wind with a simple configuration.

The present invention has been made to solve the above-mentioned problems, and one aspect of the present invention is to provide a speaker and a plurality of microphones arranged at least one at each of the positions facing each other across the speaker. A sound wave reflection time measuring unit that measures the reflection time from when sound waves are output from the speaker to when they are reflected on the object surface and reach each of the plurality of microphones, which is a measuring device to be measured by using the above . A sound wave reflection time model showing the relationship between the wind speed and direction with respect to the object surface, the distance between the speaker and the object surface, the angle between the speaker and the plurality of microphones with respect to the object surface, and the reflection time. A measuring device including an estimation unit for estimating the wind speed and the distance based on the measured value of the reflection time.

Another aspect of the present invention is a mobile body including the speaker, the plurality of microphones, and the measuring device according to any one of claims 1 to 4.

Further, another aspect of the present invention is a measurement method of a measuring device that measures using a speaker and a plurality of microphones arranged at least one at each of the positions facing each other with the speaker interposed therebetween. A sound wave reflection time measurement step for measuring the reflection time from when is output from the speaker to the reflection on the object surface and reaching each of the plurality of microphones, the wind speed and direction with respect to the object surface, and the speaker. Based on a sound wave reflection time model showing the relationship between the distance between the speaker and the object surface , the angle between the speaker and the plurality of microphones with respect to the object surface, and the reflection time, and the measured value of the reflection time. The measurement method includes the wind speed and the estimation step for estimating the distance .

According to the present invention, it is possible to accurately measure information about the wind around the structure with a simple configuration.

The figure which shows the concept of the wind speed remote measurement method which concerns on 1st Embodiment. The figure which shows the sound wave reflection model which concerns on 1st Embodiment. The figure which shows the input (applied voltage waveform) to a speaker. The figure which shows the output (reception waveform) of a microphone. The figure which shows the input to a speaker (the applied voltage waveform whose phase was changed in the middle). The figure which shows the output of a microphone (the reception waveform of the sound wave whose phase was changed in the middle). The figure which shows an example of the calculation result of the value of the cross-correlation function of a direct sound wave form and a received waveform. The block diagram which shows an example of the structure of the drone which concerns on 1st Embodiment. The block diagram which shows an example of the structure of the control part which concerns on 1st Embodiment. The flowchart which shows an example of the wind speed remote measurement processing which concerns on 1st Embodiment. The figure explaining the outline of an experiment. A photograph of the speaker and microphone installed in the experiment. A photograph of the wind tunnel used in the experiment. A table showing the experimental conditions. A block diagram showing the configuration of the experimental system. The figure which shows the experimental result. The figure which shows an example of the sound wave reflection model which concerns on 2nd Embodiment. The figure which shows an example of the sound wave reflection model which concerns on 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same parts are designated by the same reference numerals.
[First Embodiment]
The first embodiment of the present invention will be described.
First, an outline of the wind speed remote measurement method according to the embodiment of the present invention will be described.
FIG. 1 is a diagram showing an outline of a wind speed remote measurement method according to an embodiment of the present invention. The wind speed remote measuring device according to the present embodiment measures by utilizing the fact that the reflection time of sound waves on a structure or the like changes depending on the wind. Specifically, the wind speed remote measuring device outputs a sound wave (for example, ultrasonic wave) from the speaker 15, receives the sound wave reflected by the wall surface of a structure or the like with the microphone 16, and measures the received waveform (received sound wave waveform). do. Further, the wind speed remote measuring device discriminates the sound wave reflection time by using the sound wave reflection time discriminating method based on this received waveform, and determines the measured value of the sound wave reflection time (sound wave reflection time measured value). Next, the wind speed remote measuring device includes a sound wave reflection time model formula (sound wave reflection time model formula) and the above-mentioned sound wave reflection time model formula (sound wave reflection time model formula) showing the relationship between the wind speed, the wind direction, the distance and angle of the structure and the like from the wall surface, and the sound wave reflection time. Based on the sound wave reflection time measurement value, the estimation algorithm is used to estimate the wind velocity, wind direction, distance or angle with the wall surface of the structure, etc. (so-called reverse problem). The reflection time model formula does not have to be a mathematical formula, and may be, for example, a set of values.
Hereinafter, the above-mentioned sound wave reflection time model formula, a method for discriminating the sound wave reflection time measurement value, and an estimation algorithm based on the sound wave reflection time model formula and the sound wave reflection time measurement value will be described in detail.

(Sonic reflection time model formula)
First, the sound wave reflection time model formula according to this embodiment will be described. FIG. 2 is a diagram showing a sound wave reflection model according to the present embodiment. This figure is an example of a sound wave reflection model in a two-dimensional space and is defined by xy coordinates. Further, here, a sound wave reflection model in the case of two microphones is shown. In the illustrated sound wave reflection model, the wind speed is V and the wind direction (angle of the wind direction with respect to the wall surface) is Φ.

It is assumed that the center of the output of the speaker 15 is the intersection (origin) of the x-axis and the y-axis, and the two microphones 16 (16a, 16b) are located on the x-axis with the speaker 15 in between. The microphone 16a is the microphone 1, the microphone 16b is the microphone 2, and "1" and "2" attached to the back of the microphone are microphone numbers for identifying the microphone. When the distance between the speaker 15 and the microphone 16 is di ( _i is the microphone number), the xy coordinates of the microphone 16a (microphone 1) are (d ₁ , 0) and the xy coordinates of the microphone 16b (microphone 2) are (). -D ₂ , 0). Further, assuming that the distance from the speaker 15 to the wall surface is L in the direction perpendicular to the output surface of the speaker 15 (y-axis direction), the xy coordinates of the intersection of the wall surface and the y-axis are (0, L). Further, the sensor angle with respect to the wall surface (the angle between the speaker 15 and the microphone 16 with respect to the wall surface, that is, the angle between the wall surface and the x-axis) is defined as θ.

Further, the xy coordinates of the position where the sound wave output from the speaker 15 is reflected on the wall surface until it reaches the microphone 16 of the microphone number i are set as ( _xi , y _i ), and the xy coordinates (x) of the wall surface from the speaker 15 are set. Let l _ini be the distance to the position of _i , y _i ), and let l _rei be the distance from the position of the xy coordinates ( _xi , y _i ) of the wall surface to the microphone 16. For example, if the sound wave output from the speaker 15 is reflected at the position of the xy coordinates (x ₁ , y ₁ ) on the wall surface and reaches the microphone 16a (microphone 1), the xy coordinates (x ₁ , 1,) on the wall surface from the speaker 15 are assumed. Let l in ₁ be the distance to the position of y ₁ ), and let l _re 1 be the distance from the position of the xy coordinates (x ₁ , y ₁ ) on the wall surface to the microphone 16a (microphone 1). Further, the angle between the line segment from the speaker 15 to the xy coordinates (x ₁ , y ₁ ) of the wall surface and the x axis is set to θ in ₁ . On the other hand, if the sound wave output from the speaker 15 is reflected at the position of the wall surface xy coordinates (x ₂ , y ₂ ) and reaches the microphone 16b (microphone 2), the wall surface xy coordinates (x ₂ , y 2) from the speaker 15 are reached. Let l _{in 2} be the distance to the position of y ₂ ), and let l _re 2 be the distance from the position of the xy coordinates (x ₂ , y ₂ ) on the wall surface to the microphone 16b (microphone 2). Further, the angle between the line segment from the speaker 15 to the xy coordinates (x ₂ , y ₂ ) of the wall surface and the x axis is θ _{in 2} .

In the sound wave reflection model shown in FIG. 2 described above, the sound wave reflection time model formula for calculating the sound wave reflection time calculated value Ti is the mathematical formula 1 shown below. C is the speed of sound.

The calculated value of the sound wave reflection time can be obtained by using the sound wave reflection time model formula shown in the above formula 1.

(Estimation algorithm)
Next, an estimation algorithm for estimating the wind speed, wind direction, distance or angle to the wall surface, etc. based on the sound wave reflection time model formula and the sound wave reflection time measurement value will be described.
Assuming that the wind speed V, the wind direction Φ, the distance L to the wall surface, and the sensor angle θ with respect to the wall surface are the optimization parameters x, the sound wave reflection time model equation can be expressed as the following equation 2.

Further, the sound wave reflection time measurement value based on the reception result of the sound wave actually output from the speaker 15 reflected on the wall surface and received by the microphone 16 is expressed as follows.

Then, the evaluation function J can be expressed by the following mathematical formula 3 as an estimation algorithm for estimating the wind speed, the wind direction, the distance to the wall surface, the angle, etc. using the above-mentioned sound wave reflection time model formula and the sound wave reflection time measurement value. ..

The above equation 3 indicates that the optimization parameter x that minimizes the evaluation function J is obtained. By obtaining the optimization parameter x that minimizes the evaluation function J, the wind speed V, the wind direction Φ, the distance L from the wall surface, and the sensor angle θ with respect to the wall surface can be estimated.

For example, when the wind direction Φ and the sensor angle θ with respect to the wall surface are set as known values and the wind speed V and the distance L to the wall surface are estimated using two microphones 16 in the sound wave reflection model shown in FIG. 2, the following As shown in Equation 4, the optimization parameter x is a variable between the wind speed V and the distance L from the wall surface.

In this case, using the optimization parameter x, the sound wave reflection time model equation can be expressed as the following equation 5.

Then, as the estimation algorithm, the evaluation function J can be expressed by the following mathematical formula 6.

In this equation 5, the wind speed V and the distance L from the wall surface can be estimated by obtaining the optimization parameter x that minimizes the evaluation function J.

(Sonic reflection time discrimination method)
Next, a method for determining the sound wave reflection time when determining the sound wave reflection time measurement value based on the received waveform received by the microphone 16 from the sound wave reflected wave output from the speaker 15 will be described.
The speaker 15 is, for example, an ultrasonic speaker that outputs ultrasonic waves. Ideally, it is desirable to be able to transmit and stop sound waves abruptly, but this is difficult because of the mechanical resonance phenomenon.

In FIGS. 3 and 4, the speaker 15 and the microphone 16 are opposed to each other at a distance of 10 cm, and an input to the speaker 15 (applied voltage waveform) and a sound wave (ultrasonic wave) output from the speaker 15 in response to the input are shown. The output (received waveform) of the microphone 16 when directly received is shown. FIG. 3 is a diagram showing an input (applied voltage waveform) to the speaker 15, in which the vertical axis represents the input voltage to the speaker 15 and the horizontal axis represents time. On the other hand, FIG. 4 is a diagram showing the output (received waveform) of the microphone 16, in which the vertical axis represents the output voltage of the microphone 16 and the horizontal axis represents the time from the arrival time of the sound wave. With reference to FIGS. 3 and 4, it can be seen that the amplitude of the microphone 16 increases and decreases slowly with respect to the input to the speaker 15. That is, it can be seen that the speaker 15 cannot suddenly transmit and stop sound waves. Further, referring to FIG. 4, it can be seen that it is difficult to detect the first wave of the sound wave from the received waveform of the microphone 16. Therefore, even when determining the sound wave reflection time measurement value based on the received waveform, it is difficult to detect the first wave of the sound wave reflected wave from the received waveform of the microphone 16, and it is difficult to determine the reflection time. Further, it is difficult to determine the reflection time by obtaining the cross-correlation function between the voltage waveform applied to the speaker 15 and the received waveform of the microphone 16.

Further, there is also a problem that a large sound pressure cannot be obtained unless the resonance frequency of the speaker 15 and the frequency of the applied voltage waveform are matched. Therefore, when the frequency is swept, it is difficult to obtain a cross-correlation function between the voltage waveform applied to the speaker 15 and the received waveform of the microphone 16, and it is also difficult to determine the reflection time.

Therefore, first, the speaker 15 and the microphone 16 are opposed to each other, and the direct sound wave form (for example, the received waveform shown in FIG. 4) in which the sound wave output from the speaker 15 is directly measured is measured in advance. Then, the sound wave reflection time is determined by obtaining the cross-correlation function between this direct sound wave type and the received waveform of the sound wave that actually hits the wall surface and is reflected. This makes it possible to accurately determine the measured value of the sound wave reflection time rather than finding the cross-correlation function with the input to the speaker 15 (applied voltage waveform).

Further, the accuracy of discriminating the sound wave reflection time may be improved by inputting (applying) an applied voltage waveform to the speaker 15 so as to obtain a more characteristic received waveform. For example, as shown in FIG. 5, the applied voltage waveform whose phase is changed during the measurement is input to the speaker 15. FIG. 5 is a diagram showing an input (applied voltage waveform) to the speaker 15, and is a diagram showing an example of an applied voltage waveform whose phase is changed during the measurement. In this figure, the vertical axis is the input voltage to the speaker 15, and the horizontal axis is time. In the illustrated example, a 40 kHz square wave signal whose phase is changed by 180 degrees is input to the speaker 15. FIG. 6 is a diagram showing the output of the microphone 16 facing the speaker 15 (the reception waveform of the sound wave whose phase is changed in the middle), and the sound wave (the sound wave output from the speaker 15 when the applied voltage waveform shown in FIG. 5 is used). It is a figure which shows an example of the output (reception waveform) of the microphone 16 which directly received an ultrasonic wave). As shown in FIG. 6, since the characteristic received waveform is obtained by changing the phase in the middle while maintaining the sound pressure, the accuracy of discriminating the sound wave reflection time by the cross-correlation function is improved. Can be done.

As described above, the sound wave reflection time is discriminated by obtaining the cross-correlation function between the direct sound wave type in which the sound wave output from the speaker 15 is directly measured and the received waveform of the sound wave actually reflected on the wall surface. Although the accuracy can be improved, the received waveform may still change in the process of reflection as compared with the direct sound wave type due to various measurement errors and the like. As a result, for example, the discriminant result of the sound wave reflection time by the cross-correlation function between the direct sound wave type and the received waveform may be deviated by an integer wavelength.

FIG. 7 is a diagram showing an example of the calculation result of the cross-correlation function between the direct sound wave type and the received waveform. In this figure, the vertical axis is the value of the cross-correlation function, and the horizontal axis is the time shift amount. For example, the time shift τ ₃ that maximizes the value of the cross-correlation function is set as the reflection time. As described above, when the received waveform is changed due to various measurement errors or the like, this time shift τ ₃ is correct. It is not always the reflection time.

Therefore, in the present embodiment, the sound wave reflection time measurement value is determined based on a plurality of peak values including the maximum value of the cross-correlation function. For example, as shown in FIG. 7, in addition to the maximum value of the cross-correlation function, five time shifts τ ₁ to τ ₅ corresponding to the two peak values before and after are used as candidates for the reflection time. Then, the time shifts τ ₁ to τ ₅ are obtained for each microphone. For example, when two microphones, a microphone 16a (microphone 1) and a microphone 16b (microphone 2), are used, five time shifts τ ₁ to τ ₅ are obtained for each of the two microphones. Then, the above-mentioned estimation algorithm (see, for example, Equation 5) is applied to all the obtained combinations, and the time shift amount obtained by the solution is used as the sound wave reflection time measurement value. As a result, even if the received waveform may change in the process of reflection due to various measurement errors, etc., the accuracy of discriminating the sound wave reflection time by the cross-correlation function can be further improved. Can be done.

Next, a configuration example of a small unmanned aircraft to which the wind speed remote measurement method according to the present embodiment is applied will be described. A small unmanned aerial vehicle is, for example, a drone, which is a small aircraft that can fly unmanned by remote control or automatic control.
FIG. 8 is a block diagram showing an example of the configuration of the drone according to the present embodiment. The illustrated drone 10 includes a communication unit 11, a drive unit 12, a storage unit 13, a control unit 14, a speaker 15, and two microphones 16 (16a, 16b).

The communication unit 11 performs wireless communication with a controller (not shown) for remotely controlling the drone 10. For example, the communication unit 11 receives information indicating the operation content from the controller (not shown) based on the user operation. Further, the communication unit 11 transmits information indicating the state of the drone 10 to the controller (not shown) as needed.

The communication unit 11 may communicate with a server device or another device via a communication network such as the Internet.

The drive unit 12 includes a plurality of motors and a plurality of propellers that are interlocked with the rotation of the motor shaft of each motor. The drive unit 12 drives the rotation of each motor according to the control of the control unit 14, and generates lift and thrust by rotating the propeller, enabling the drone 10 to fly.

Although not shown in this figure, the drone 10 includes, for example, an acceleration sensor, a gyro sensor, or a directional sensor for detecting the movement or posture of the aircraft, a battery for supplying power to each part, and the like. Further, the drone 10 may be provided with a camera or the like capable of taking a picture from the sky.

The storage unit 13 stores various information of the drone 10. For example, the storage unit 13 stores a control program related to flight control by the control unit 14. Further, the storage unit 13 stores parameters related to the sound wave reflection time model related to the above-mentioned wind speed remote measurement method, a sound wave reflection time model formula, an estimation algorithm, and the like.

The control unit 14 includes a CPU (Central Processing Unit), and executes various processes for controlling the drone 10 by executing a control program stored in the storage unit 13. For example, the control unit 14 is a drive unit based on information indicating the operation content received from a controller (not shown) operated by the user via the communication unit 11, and the detection result of the movement and posture of the drone 10 aircraft. The flight of the drone 10 is controlled by controlling the drive of the twelve. Further, the control unit 14 estimates information about the wind around the drone 10 by the above-mentioned wind speed remote measurement method using the speaker 15 and the microphones 16 (16a, 16b), and uses it for the flight control of the drone 10. do.

The speaker 15 is, for example, an ultrasonic speaker capable of outputting ultrasonic waves. The microphone 16 (16a, 16b) is, for example, an ultrasonic microphone capable of receiving ultrasonic waves. The speaker 15 and the two microphones 16 (16a, 16b) are provided on the side surface of the drone 10. Specifically, as shown in FIG. 2, the speaker 15 and the two microphones 16 (16a, 16b) face each other on a straight line, and the two microphones 16 (16a, 16b) face each other with the speaker 15 in between. It is installed on the side of the aircraft so that it is in a position. For example, the speaker 15 and the two microphones 16 (16a, 16b) are arranged on the side surface of the airframe in a straight line in a direction corresponding to the horizontal direction during flight. Further, the speaker 15 is installed so as to output a sound wave (ultrasonic wave) in a direction facing the machine body surface. Each of the two microphones 16 (16a, 16b) is installed so as to face the airframe surface so that the reflected wave of the sound wave (ultrasonic wave) output from the speaker 15 can be received.

In the above description, an example in which the speaker 15 and the plurality of microphones 16 are installed on a straight line has been described. By arranging the speaker 15 and the plurality of microphones 16 in a straight line in this way, a simple model formula can be obtained, whereby the sound wave reflection time can be easily calculated. The speaker 15 and the plurality of microphones 16 do not have to be installed on a straight line, and the sound wave reflection time can be calculated even if they are installed at positions deviated from the straight line. Further, the speaker 15 and the two microphones 16 (16a, 16b) may be installed on one of the side surfaces of the drone 10 or may be installed on each of the plurality of side surfaces. For example, when it is installed on one of the sides of the aircraft, the side may be steered so as to face the direction of travel, and wind information in the direction of travel may be measured remotely. In addition, by installing on all sides of the aircraft (for example, if there are four sides, all four sides), wind information in the entire circumference direction of the aircraft (for example, four directions) can be measured remotely. You may. Further, the speaker 15 and the two microphones 16 (16a, 16b) are not limited to the side surface of the aircraft as long as they can output sound waves around the drone 10 and receive the reflected waves of the sound waves. Can be installed in the location of.

Next, the configuration of the control unit 14 will be described in detail with reference to FIG. Here, among the configurations of the control unit 14, a functional configuration for estimating information about the wind around the drone 10 by the wind speed remote measurement method will be described. FIG. 9 is a block diagram showing an example of the configuration of the control unit 14 according to the present embodiment. The control unit 14 illustrated is a measurement device 141 that estimates information about the wind around the drone 10 by the above-mentioned wind speed remote measurement method, and a drive control unit 142 that controls the drive of the drive unit 12 based on the estimation result and the like. And have.

The measuring device 141 includes a sound wave reflection time measuring unit 1411 and an estimating unit 1412. The sound wave reflection time measuring unit 1411 receives the reflected wave from the wall surface of the sound wave output from the speaker 15 by the two microphones 16 (16a, 16b), and after the sound wave is output from the speaker 15, 2 The reflection time until reaching each of the microphones 16 (16a, 16b) is measured. For example, the sound wave reflection time measuring unit 1411 outputs a sound wave (for example, an ultrasonic wave) having a predetermined frequency from the speaker 15 as shown in FIG. Here, the sound wave reflection time measuring unit 1411 outputs a sound wave whose phase has been changed (shifted). For example, the sound wave reflection time measuring unit 1411 changes the phase by 180 degrees on the way. The amount of the phase to be changed is not limited to 180 degrees, and may be, for example, 90 degrees.

Further, the sound wave reflection time measuring unit 1411 has a direct sound wave type that directly measures the sound wave output from the speaker 15 that has been measured in advance, and a received waveform received by each of the two microphones 16 (16a, 16b). The cross-correlation function may be obtained, and the sound wave reflection time measurement value may be determined based on a plurality of peak values including the maximum value of the cross-correlation function. For example, as shown in FIG. 7, the sound wave reflection time measuring unit 1411 has five time shifts τ ₁ to corresponding to two peak values before and after in addition to the maximum value of the cross-correlation function between the direct sound wave shape and the received waveform. Let τ ₅ be a candidate for the reflection time (candidate for the sound wave reflection time measurement value), and obtain the time shifts τ ₁ to τ ₅ for each microphone.

The estimation unit 1412 includes a sound wave reflection time model equation (see FIG. 2 and Equation 1) showing the relationship between the distance between the speaker 15 or the two microphones 16 (16a, 16b) and the wall surface, the wind velocity, and the wind direction and the reflection time. , Information on the wind is estimated using an estimation algorithm (see, for example, Equations 3 and 5) based on the sound wave reflection time measurement value measured by the sound wave reflection time measurement unit 1411. For example, the estimation unit 1412 applies an estimation algorithm (see Equations 3 and 5) to all combinations of the five candidate sound wave reflection time measurement values with the wind direction Φ and the sensor angle θ with respect to the wall surface as known values. Then, by obtaining the optimization parameter x that minimizes the evaluation function J, the wind speed around the drone 10 and the distance from the wall surface are estimated.

The drive control unit 143 controls the drive of the drive unit 12 based on the estimation result of the measuring device 141 and the like. For example, the drive control unit 143 is a drive unit based on information indicating the control content received from a controller (not shown) operated by the user via the communication unit 11, and the detection result of the movement and posture of the drone 10 aircraft. In addition to controlling the drive of the drive 12, the drive of the drive unit 12 is controlled by adding information about the wind around the drone 10 based on the estimation result by the measuring device 141. For example, the drive control unit 143 uses the distribution of the wind measured remotely by the measuring device 141 to generate an optimum route for moving to the destination without being affected by the wind, and for optimal control to reduce the influence of the wind. It is also possible to generate and control the drive of the drive unit 12 based on them. This enhances the robustness of the flight of the drone 10 in adverse environments such as strong winds and gusts, and enables stable flight control.

Next, the wind speed remote measurement process in which the measuring device 141 according to the present embodiment estimates information about the wind by the wind speed remote measurement method will be described.
FIG. 10 is a flowchart showing an example of the wind speed remote measurement process according to the present embodiment.

(Step S10) The measuring device 141 outputs a sound wave (for example, an ultrasonic wave) whose phase has been changed from the speaker 15, and changes the phase of the sound wave to be output during the measurement. For example, the measuring device 141 changes the phase by 180 degrees on the way (see FIG. 5). Then, the process proceeds to step S12.

(Step S12) The measuring device 141 acquires a reception result of receiving the reflected wave from the wall surface of the sound wave (for example, ultrasonic wave) output from the speaker 15 by the two microphones 16 (16a, 16b). Then, the process proceeds to step S14.

(Step S14) The measuring device 141 has a direct sound wave type (see FIG. 6) in which the sound wave output from the speaker 15 measured in advance is directly measured, and a reception result (two microphones 16 (16a)) acquired in step S12. , 16b), the cross-correlation function with the received waveform received in each of 16b) is obtained, and the sound wave reflection time measurement value is determined based on a plurality of peak values including the maximum value of the cross-correlation function. For example, the measuring device 141 sets five time shifts τ ₁ to τ ₅ corresponding to two peak values before and after, in addition to the maximum value of the cross-correlation function between the direct sound wave type and the received waveform, as candidates for the sound wave reflection time measurement value. Then, the time shifts τ ₁ to τ ₅ are obtained for each microphone (see FIG. 7). Then, the process proceeds to step S16.

(Step S16) The measuring device 141 is a sound wave reflection time model equation (FIG. 2 and mathematical formula) showing the distance between the speaker 15 or the two microphones 16 (16a, 16b) and the wall surface, the wind speed, and the relationship between the wind direction and the reflection time. 1) and the sound wave reflection time measurement value measured in step S14 are used to estimate information about the wind using an estimation algorithm (see Equation 3, Equation 5, etc.). For example, the measuring device 141 applies an estimation algorithm (see Equations 3 and 5) to all combinations of the five candidate sound reflection time measurement values with the wind direction Φ and the sensor angle θ with respect to the wall surface as known values. Then, by obtaining the optimization parameter x that minimizes the evaluation function J, the wind speed V around the drone 10 and the distance L from the wall surface are estimated.

(Experimental example of wind speed remote measurement method)
Next, an example of the experimental results for verifying the validity of the wind speed remote measurement method described above will be described.
FIG. 11 is a diagram illustrating an outline of the experiment. In the experiment, one speaker and two microphones (microphone 1 and microphone 2) were installed in the wind tunnel. The inner wall of the wind tunnel corresponds to the wall surface, and basically the conditions of the sound wave reflection model shown in FIG. 2 were reproduced. FIG. 12 is a photograph of the installed state of the speaker and the microphone used in the experiment. In this photograph, two microphones are installed in each of the microphone 1 and the microphone 2, but in this experiment, only one microphone each (two microphones in total) is used in the experiment. Further, FIG. 13 is a photograph of the wind tunnel used in the experiment. The wind tunnel used was from the Kanazawa University Aerospace Systems Laboratory, with a flow velocity of 2 to 25 m / s and a test section of 200 x 200 x 500 mm.

FIG. 14 is a table showing experimental conditions. The microphone 1 and the microphone 2 are located so as to face each other on a straight line with the speaker in between, and the distance d from the speaker is set to 20 cm. The distance L ₀ (distance from the inner wall to the inner wall in the vertical direction) between the speaker and the inner wall of the wind tunnel was set to 12.2 cm. Further, the wind direction was set to 0 deg, and the sensor angle θ with respect to the inner wall was changed to 3 types of −5, 0, and 5 deg for measurement. Further, the wind speed V was measured by changing it to 6 types of 0, 2, 4, 6, 8, and 10 m / s. The sampling period was 2 μs, and the sound wave transmission interval was 0.01 s.

Further, FIG. 15 is a block diagram showing the configuration of the experimental system. The speaker drive signal output from the function generator is input to the speaker amplifier and data logger. The speaker amplifier amplifies the speaker drive signal and outputs it to the speaker. The microphone amplifier outputs an amplified signal obtained by amplifying the output signal of the microphone to a data logger. The data logger samples and records the amplified signal output from the microphone amplifier based on the speaker drive signal output from the function generator, and outputs it to a personal computer (personal computer). The number of microphone amplifiers is provided according to the number of microphones. Here, two microphone amplifiers corresponding to two microphones are provided. Each microphone amplifier amplifies the output signal of the microphone connected to each and outputs it to the data logger. In this experiment, DF1906 manufactured by NF Circuit Design Block was used as the function generator. As the data logger, NR-600 manufactured by KEYENCE was used.

FIG. 16 is a diagram showing the experimental results. Here, as an experimental result, the estimation results of the wind speed V and the distance L from the wall surface are shown in a graph. In this figure, the upper part shows the estimation result of the wind speed V, and shows three kinds of graphs when the sensor angle θ with respect to the inner wall is changed to three kinds of -5, 0, and 5 deg. On the other hand, the lower part shows the estimation result of the distance L from the wall surface, and similarly shows three types of graphs when the sensor angle θ with respect to the inner wall is changed to three types of -5, 0, and 5 deg. .. In each graph, the horizontal axis is the set wind speed (set wind speed). In these graphs, the estimated value and the true value for each of the set wind speeds 0, 2, 4, 6, 8, and 10 m / s are shown. By referring to these graphs, it can be seen that there is no big difference between the estimation result and the true value, and the wind speed V and the distance L from the wall surface can be estimated accurately.

As described above, the measuring device 141 according to the present embodiment includes a sound wave reflection time measuring unit 1411 and an estimation unit 1412. The sound wave reflection time measuring unit 1411 receives the reflected wave from the wall surface (an example of an object) of the sound wave output from the speaker 15 by a plurality of microphones, and the sound wave is output from the speaker 15 and then a plurality. Measure the reflection time (measured value of sound wave reflection time) until reaching each of the microphones. The estimation unit 1412 includes a sound wave reflection time model formula showing the relationship between the wind speed, the wind direction, the distance between the speaker 15 or a plurality of microphones 16 and a wall surface (an example of an object), and the reflection time, and a sound wave reflection time measuring unit. The wind velocity and the distance to the wall surface (an example of an object) are estimated based on the sound wave reflection time measurement value measured by 1411.

As a result, the measuring device 141 has a simple configuration using, for example, one speaker 15 and two microphones 16 (16a, 16b), and summarizes information about the wind and the distance to the wall surface (an example of an object). Therefore, it is possible to accurately measure information about the wind around the structure (for example, prior information such as wind speed).

For example, the sound wave reflection time measuring unit 1411 may output a sound wave whose phase has been changed (for example, changed by 180 degrees) from the speaker 15. As a result, the measuring device 141 can obtain a characteristic received waveform by changing the phase in the middle while maintaining the sound pressure, so that the accuracy of discriminating the sound wave reflection time by the cross-correlation function is improved. Can be done.

Further, the sound wave reflection time measuring unit 1411 obtains a cross-correlation function between the direct sound wave type in which the sound wave output from the speaker 15 measured in advance is directly measured and the received waveform received by each of the plurality of microphones 16. , The sound wave reflection time measurement value is determined based on a plurality of peak values of the cross-correlation function. For example, the sound wave reflection time measurement unit 1411 determines the sound wave reflection time measurement value based on a plurality of peak values including the maximum value of the cross-correlation function.

As a result, the measuring device 141 can further improve the discrimination accuracy of the sound wave reflection time by the cross-correlation function even if the received waveform may change in the process of reflection as compared with the direct sound wave type. ..

In this embodiment, as shown in FIG. 7, an example in which the sound wave reflection time measurement value is determined based on the maximum value of the cross-correlation function and the two peak values before and after each is described, but the present invention is limited to this. It is not something that can be done. For example, the number of peak values used before and after the maximum value of the cross-correlation function can be arbitrarily determined. Further, a plurality of peak values other than the maximum value of the cross-correlation function may be used.

Further, since the drone 10 equipped with the measuring device 141 can control the flight of the drone 10 by adding information on the wind around the drone 10, the flight of the drone 10 in a bad environment such as a strong wind or a gust of wind It enhances the robustness and enables stable flight control. For example, the drone 10 uses the wind distribution measured remotely by the measuring device 141 to generate an optimum route that moves to the destination without being affected by the wind, and to generate an optimum control that reduces the influence of the wind. It is also possible to control the drive of the drive unit 12 based on them.

(Second embodiment)
Next, a second embodiment of the present invention will be described. In the first embodiment, an example of estimating the wind speed V and the distance L to the wall surface using two microphones has been described, but by adding more microphones, the wind direction Φ and the sensor angle θ with respect to the wall surface can also be obtained. Estimation is possible. In this embodiment, a configuration including four microphones will be described.

FIG. 17 is a diagram showing an example of a sound wave reflection model when the number of microphones according to the present embodiment is four. The sound wave reflection model shown in this figure has a different number of microphones from the sound wave reflection model shown in FIG. The microphone 16a (microphone 1) and the microphone 16c (microphone 3) and the microphone 16b (microphone 2) and the microphone 16d (microphone 4) are located at opposite positions with the speaker 15 interposed therebetween. Even when there are four microphones, the sound wave reflection time model formula for calculating the calculated value Ti of the sound wave reflection time can be expressed by the above-mentioned formula 1.

The optimization parameter x is a variable of the wind speed V, the wind direction Φ, the distance L to the wall surface, and the sensor angle θ with respect to the wall surface, as shown in the following mathematical formula 7.

Further, the sound wave reflection time model equation can be expressed as the following equation 8 using the optimization parameter x.

Further, the sound wave reflection time measurement value is expressed as follows as in the first embodiment.

Then, the evaluation function J can be expressed as the following equation 9 as an estimation algorithm for estimating the wind speed V, the wind direction Φ, the distance L from the wall surface, and the sensor angle θ with respect to the wall surface.

In this equation 9, by obtaining the optimization parameter x that minimizes the evaluation function J, the wind speed V, the wind direction Φ, the distance L from the wall surface, and the sensor angle θ with respect to the wall surface can be estimated.

As described above, in the present embodiment, the measuring device 141 includes four microphones 16. Then, the estimation unit 1412 determines the wind speed, the wind direction, the distance to the wall surface (an example of the object), and the distance to the wall surface (an example of the object) based on the sound wave reflection time model formula and the sound wave reflection time measurement value measured by the sound wave reflection time measurement unit 1411. The angles of the speaker 15 and the microphone 16 with respect to the wall surface (an example of an object) are estimated.

As a result, the measuring device 141 has a simple configuration using, for example, one speaker 15 and four microphones 16 (16a, 16b), in addition to the wind speed and the distance to the wall surface (an example of an object). Since it is possible to estimate the wind direction and the sensor angle with respect to the wall surface, it is possible to measure more information about the wind around the structure.

The number of microphones to be installed may be at least four, and may be, for example, five or six.

(Third embodiment)
Next, a third embodiment of the present invention will be described. In the first and second embodiments, an example of estimating the wind speed, the wind direction, the distance to the wall surface, the sensor angle with respect to the wall surface, etc. in the two-dimensional space has been described, but in the present embodiment, the example extended to the three-dimensional space has been described. explain.

FIG. 18 is a diagram showing an example of a sound wave reflection model in a three-dimensional space according to the present embodiment. In the sound wave reflection model shown in this figure, the two-dimensional space is defined by the xy coordinates, whereas the sound wave reflection model shown in FIG. 2 defines the three-dimensional space by the xyz coordinates. Here, the coordinate axes fixed to the aircraft (sensing system (measuring device) housing) such as the drone 10 are defined as the x _a axis, the _{ya axis, and the z a axis} . The center of the output of the speaker 15 is the intersection (origin) of the _xa axis, the _ya axis, and the _za axis, and the speaker 15 and at least three speakers are attached to the machine such as the drone 10 (sensing system (measuring device) housing). It is assumed that the above microphones are provided. In the illustrated example, the microphone 16a (microphone 1), the microphone 16b (microphone 2), and the microphone 16i (microphone i) are arranged in the radial direction with the speaker 15 as the center, and the speakers 15 to each microphone 16 are arranged. Let the distance vector be di ( _i is the microphone number).

Further, as in the example of FIG. 2, the distance from the speaker 15 to the wall surface in the direction perpendicular to the output surface of the speaker 15 is set to L, and the sound wave output from the speaker 15 is reflected on the wall surface to be reflected by the microphone 16a (microphone 1). ) Is defined as the distance from the speaker 15 to the wall surface, and the distance from the wall surface to the microphone 16a (microphone 1) is _{defined as l re1 .} Further, in the path where the sound wave output from the speaker 15 is reflected on the wall surface and reaches the microphone 16b (microphone 2), the distance from the speaker 15 to the wall surface is l _in2 , and the distance from the wall surface to the microphone 16b (microphone 2) is set. Let l _re2 . Further, in the path where the sound wave output from the speaker 15 is reflected on the wall surface and reaches the microphone _16i (microphone i), the distance from the speaker 15 to the wall surface is mini, and the distance from the wall surface to the microphone 16b (microphone 2) is set. Let l _rei .

Further, assuming that the attitude angle of the aircraft or the sensor with respect to the wall surface (angle of the speaker 15 and the microphone 16 with respect to the wall surface) is θ ₁ and θ ₂ , the wind velocity vector is V, and the sound velocity is C, the calculated value Ti of the sound wave reflection time is calculated. The sound wave reflection time model formula can be expressed by the formula 10 shown below.

The optimization parameter x is a variable of the wind speed vector V, the distance L to the wall surface, and the sensor attitude angles θ ₁ and θ ₂ with respect to the wall surface, as shown in Equation 11 below.

Further, the sound wave reflection time model equation can be expressed as the following equation 12 using the optimization parameter x.

Further, the sound wave reflection time measurement value is expressed as follows as in the first embodiment.

Then, as the estimation algorithm, the evaluation function J can be expressed as the following mathematical formula 13.

In this way, using the sound wave reflection model corresponding to the three-dimensional space, the distance between the wind velocity vector V and the wall surface in the three-dimensional space is obtained by obtaining the optimization parameter x that minimizes the evaluation function J in the above equation 13. L can be estimated. Further, by further adding speakers, it is possible to estimate the sensor attitude angles θ ₁ and θ ₂ with respect to the wall surface in addition to the wind speed vector V and the distance L from the wall surface in the three-dimensional space.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist of the present invention. It is possible to do. For example, the configurations described in the first to third embodiments described above can be arbitrarily combined.

Further, in the above-described embodiment, an example in which a plurality of microphones 16 are installed, such as when the number of microphones 16 is two or at least four or more, has been described, but the number of speakers 15 is not limited to one. There may be more than one. Further, the speaker 15 may be a phased array speaker.

Further, in the above-described embodiment, an example in which the object on which the sound wave is reflected is a wall surface of a structure or the like has been described, but the object may be any object as long as it reflects the sound wave. ..

Further, the measuring device 141 may send the measured wind information (wind speed, wind direction, distance to the wall surface, sensor angle with respect to the wall surface, etc.) to another device via the communication unit 11. The destination may be a server device connected via a communication network, or may be a controller for remotely controlling the drone 10. As a result, information on the wind around the drone 10 can be confirmed or used even at a place away from the drone 10.

In addition, a part or all of the control unit 14 in the above-described embodiment may be realized by a computer. In that case, a program for realizing a part or all of the functions of the control unit 14 is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read by the computer system and executed. May be realized by. The "computer system" referred to here is a computer system built in the drone 10, and includes hardware such as an OS and peripheral devices. Further, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, and a storage device such as a hard disk built in a computer system. Further, a "computer-readable recording medium" is a medium that dynamically holds a program for a short time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In that case, a program may be held for a certain period of time, such as a volatile memory inside a computer system serving as a server or a client. Further, the above-mentioned program may be for realizing a part of the above-mentioned functions, and may be further realized for realizing the above-mentioned functions in combination with a program already recorded in the computer system.

Further, a part or all of the control unit 14 in the above-described embodiment may be realized as an integrated circuit such as an LSI (Large Scale Integration). Further, for example, a part or all of the control unit 14 may be integrated into a processor. Further, the method of making an integrated circuit is not limited to the LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, when an integrated circuit technology that replaces an LSI appears due to advances in semiconductor technology, an integrated circuit based on this technology may be used.

Further, in the above-described embodiment, the configuration in which the measuring device 141 is provided in the drone 10 has been described, but the measuring device 141 may be provided in a device different from the drone 10. For example, the measuring device 141 may be provided in a controller for remotely controlling the drone 10, or may be provided in a server device connected via a communication network. In these cases, the drone 10 transmits the reception result received by the microphone 16 to the controller or the server device, so that the controller or the server device estimates information about the wind, and the estimation result is fed back to the drone 10. May be good. At this time, the output of the speaker 15 may be controlled autonomously by the drone 10, or by transmitting a control signal from the controller or the server device to the drone 10, the drone 10 may control the output of the speaker 15 based on the control signal. You may control it.

Further, in the above-described embodiment, an example in which the measuring device 141 is applied to the drone 10 has been described, but it may be applied to any flying object, not limited to the drone 10, and is not limited to a flying object, and is not limited to a vehicle. It may be applied to a moving body such as.

10 drone, 11 communication unit, 12 drive unit, 13 storage unit, 14 control unit, 15 speaker, 16 microphone, 141 measuring device, 1411 sound wave reflection time measuring unit, 1412 estimation unit, 142 drive control unit

Claims (6)

It is a measuring device that measures using a speaker and a plurality of microphones arranged at least one at each of the positions facing each other across the speaker.
A sound wave reflection time measuring unit that measures the reflection time from when the sound wave is output from the speaker to when it is reflected on the object surface and reaches each of the plurality of microphones.
Sound wave reflection time indicating the relationship between the wind speed and direction with respect to the object surface, the distance between the speaker and the object surface, the angle between the speaker and the plurality of microphones with respect to the object surface, and the reflection time. An estimation unit that estimates the wind speed and the distance based on the model and the measured value of the reflection time.
A measuring device equipped with. The plurality of microphones are four or more microphones arranged at least two at each of the positions facing each other across the speaker.
The estimation unit
The wind speed, the wind direction, the distance, and the angle are estimated based on the sound wave reflection time model and the measured value of the reflection time measured by the sound wave reflection time measuring unit.
The measuring device according to claim 1. The sound wave reflection time measuring unit is
The cross-correlation function of the direct sound wave form obtained by directly measuring the sound wave output from the speaker measured in advance and the received waveform received by each of the plurality of microphones is obtained, and a plurality of peak values of the cross-correlation function are obtained. And the measured value of the reflection time is determined based on the sound wave reflection time model.
The measuring device according to claim 1 or 2. The sound wave reflection time measuring unit is
In the middle of measuring the reflection time, the phase of the sound wave output from the speaker is changed.
The measuring device according to any one of claims 1 to 3. With the speaker
With the multiple microphones
The measuring device according to any one of claims 1 to 4,
A mobile body equipped with. It is a measurement method of a measuring device that measures using a speaker and a plurality of microphones arranged at least one at each of the positions facing each other across the speaker.
A sound wave reflection time measurement step for measuring the reflection time from when the sound wave is output from the speaker to when it is reflected on the object surface and reaches each of the plurality of microphones.
Sound wave reflection time indicating the relationship between the wind speed and direction with respect to the object surface, the distance between the speaker and the object surface, the angle between the speaker and the plurality of microphones with respect to the object surface, and the reflection time. An estimation step for estimating the wind speed and the distance based on the model and the measured value of the reflection time.
Measurement method with.

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