JP2011094999A - Ultrasonic intensity distribution measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic intensity distribution measuring method, for measuring an ultrasonic intensity distribution within a measured space, capable of measuring an effective ultrasonic intensity distribution from transmitting an ultrasonic wave to receiving the ultrasonic wave reflected at points within a measured space in a system of obtaining a received signal by transmitting the an ultrasonic wave within the measured space and receiving a reflected ultrasonic wave. <P>SOLUTION: In the ultrasonic intensity distribution measuring method, a first sound pressure within the measured space is obtained by transmitting an ultrasonic wave into a measured space from a first vibrator used for transmitting the ultrasonic wave and receiving the ultrasonic wave by an ultrasonic sensor disposed within the measured space, a second sound pressure is obtained by transmitting an ultrasonic wave into the measured space from a second vibrator used essentially for receiving the ultrasonic wave and receiving the ultrasonic wave by an ultrasonic sensor disposed within the measured space, and the effective ultrasonic intensity distribution within the measured space is obtained using the first and the second sound pressures. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an ultrasonic intensity distribution measuring method for measuring an ultrasonic intensity distribution in a measurement space.

  In various fields, various safety measures are required, such as detecting that a suspicious person has entered a space where entry of persons other than authorized persons is prohibited and issuing an alarm. For example, a system that detects the intrusion of a suspicious person by transmitting ultrasonic waves from an ultrasonic transmitter into a stopped vehicle, receiving reflected ultrasonic waves by an ultrasonic receiver, and detecting ultrasonic Doppler shift can be considered. ing. In this case, there are seats and various other objects in the passenger compartment of the automobile, so that the ultrasonic waves are reflected in a complicated manner and the ultrasonic intensity distribution in the passenger compartment does not change uniformly or smoothly. It has a complex intensity distribution in the passenger compartment. For this reason, it is unclear how much intensity of ultrasonic waves should be transmitted to the passenger compartment or how much reception sensitivity should be set. Furthermore, when there is a blind spot area regardless of transmission intensity and reception sensitivity, it is also important to change the design of the vehicle interior so that the blind spot is recognized and the blind spot is minimized.

  Here, when measuring the intensity distribution of ultrasonic waves in the vehicle interior, ultrasonic waves are transmitted from the ultrasonic transmitter, and ultrasonic microphones are sequentially placed at each point in the vehicle interior, and signals received by the ultrasonic microphones are received. It is conceivable to obtain the ultrasonic intensity distribution in the passenger compartment from the intensity of the vehicle. However, in this case, the directivity of the ultrasonic receiver is ignored, and the total effective intensity distribution until the ultrasonic wave is transmitted by the ultrasonic transmitter and the reflected ultrasonic wave is received by the ultrasonic receiver. Cannot be asked.

  As another means, an ultrasonic reflector is placed in the passenger compartment instead of the ultrasonic microphone described above, and ultrasonic waves are transmitted from the ultrasonic transmitter while sequentially moving the ultrasonic reflector. It is conceivable to receive reflected ultrasonic waves and check the received intensity. However, in this case, the ultrasonic wave is not reflected only from the ultrasonic reflector, but also reflected from the wall surface of the passenger compartment, the seat in the passenger compartment, and other objects, so only the point where the ultrasonic reflector is placed. It is not possible to measure the intensity.

  In view of the above circumstances, the present invention reflects the reflected wave at each reflection point from the transmission of the ultrasonic wave in the measured space in the system that transmits the ultrasonic wave into the measured space and receives the reflected ultrasonic wave to obtain the received signal. It is an object of the present invention to provide an ultrasonic intensity distribution measuring method for measuring an effective ultrasonic intensity distribution up to reception of ultrasonic waves.

The ultrasonic intensity distribution measuring method of the present invention that achieves the above object includes: a first transducer that transmits ultrasonic waves in a measurement space; and an ultrasonic wave that is reflected and returned in the measurement space. Measurement target when operating a moving body detection apparatus including a second vibrator that obtains a reception signal and a moving body detection unit that detects the presence or absence of a moving body in the measurement space based on the reception signal. An ultrasonic intensity distribution measuring method for measuring an effective ultrasonic intensity distribution in a space,
An ultrasonic wave is transmitted from the first transducer into the measurement space, and is superposed on a first reference point that is a first reference distance away from the first transducer and a plurality of measurement points in the measurement space. A first reference sound pressure that is a sound pressure at a first reference point and a plurality of first measurement sound pressures that are sound pressures at a plurality of measurement points by arranging a sound wave sensor and causing the ultrasonic sensor to receive ultrasonic waves A first step for determining
An ultrasonic sensor is transmitted from the second vibrator into the measurement space, and is sent to a second reference point that is a second reference distance away from the second vibrator and a plurality of measurement points in the measurement space. And the ultrasonic sensor receives the ultrasonic wave to obtain the second reference sound pressure that is the sound pressure of the second reference point and the plurality of second measurement sound pressures that are the sound pressures of the plurality of measurement points, respectively. The second step;
The first ratio of each of the plurality of first measured sound pressures at each of the plurality of measurement points with respect to the first reference sound pressure obtained in the first step, and the second reference sound obtained in the second step And a third step of obtaining an effective ultrasonic intensity distribution in the measurement space based on the second ratio of each of the plurality of second measurement sound pressures at the plurality of measurement points with respect to the pressure. To do.

  The ultrasonic intensity distribution measuring method of the present invention measures an effective ultrasonic intensity distribution by using a second transducer that is originally used for ultrasonic reception for ultrasonic transmission. From the received intensity when the ultrasonic wave is transmitted from the first vibrator and received by the ultrasonic sensor and the received intensity when the ultrasonic wave is transmitted from the second vibrator and received by the ultrasonic sensor, the ultrasonic wave The effective intensity distribution of the point where the sensor is placed can be obtained, and the effective ultrasonic intensity distribution over the entire measurement space can be measured by performing it simultaneously or sequentially at each point in the measurement space. can do.

Here, in the ultrasonic intensity distribution measuring method of the present invention, the first step extracts a signal component caused by the ultrasonic wave of the frequency to be measured from the received signal obtained by receiving the ultrasonic wave by the ultrasonic sensor. Obtaining a first reference sound pressure and a plurality of first measured sound pressures based on the signal component;
The second step extracts a signal component resulting from the ultrasonic wave of the frequency to be measured from the received signal obtained by receiving the ultrasonic wave with the ultrasonic sensor, and based on the signal component, the second reference sound pressure and the plurality of sound components are extracted. It is preferable that it is a step which calculates | requires a 2nd measurement sound pressure.

  In the case of a system that detects a Doppler shift based on an ultrasonic wave of a specific frequency when a suspicious person enters, only the frequency component is extracted from the ultrasonic wave received by the ultrasonic sensor, and the ultrasonic intensity distribution based only on that frequency component Is preferably measured.

  Here, the ultrasonic intensity distribution measuring method of the present invention typically uses a vehicle cabin as a space to be measured.

  As described above, according to the present invention, an effective ultrasonic intensity distribution in the measurement space can be measured.

It is a schematic diagram which shows the ultrasonic intensity distribution measuring method of 1st Embodiment of this invention. It is the figure which looked and showed the vehicle interior from the side. It is the figure which showed the vehicle interior from the top. It is a figure which shows the frequency distribution (A) of the ultrasonic wave emitted from the 1st vibrator, and the frequency distribution (B) of the ultrasonic wave emitted from the 2nd vibrator. It is a figure which shows the ultrasonic intensity distribution only of the transmission side in a vehicle interior. It is a figure which shows the ultrasonic intensity distribution of the side originally used for reception in a vehicle interior. It is a figure which shows ultrasonic intensity distribution when both the transmission side and the receiving side are match | combined.

  Hereinafter, embodiments of the present invention will be described.

  FIG. 1 is a schematic diagram showing an ultrasonic intensity distribution measuring method according to the first embodiment of the present invention.

  The wall surface 11 that partitions the measurement space 10 includes a first vibrator 12 that transmits ultrasonic waves in the measurement space 10 and a first ultrasonic wave that is reflected and returned in the measurement space 10. Two vibrators 13 are fixed. Various reflective objects 14 exist inside the space to be measured 10. When a moving object such as a suspicious person is present in the measured space 10, the frequency of reflected ultrasonic waves from the moving object changes due to Doppler shift. Therefore, it is detected whether or not a moving object such as an intruder exists in the measured space by extracting a Doppler shifted component from the signal received by the second vibrator 13.

  The description of the scene of detecting an intruder or the like is about this level, and here, an effective ultrasonic intensity distribution measurement method in the measurement target space 10 will be described.

  FIG. 1 shows a processing circuit realized by a computer or the like.

  The processing circuit 20 includes a transmission control unit 21, a reception unit 22, a calculation unit 23, a display unit 24, and a control unit 25 that controls these units.

  Here, the ultrasonic microphone 31 is brought into the measurement space 10, and the ultrasonic intensity at each point in the measurement space is measured in the following sequence while sequentially moving in the measurement space. In this case, the second vibrator 13 is used as a reflected ultrasonic wave receiving element in a scene where an intruder is detected. Here, the second vibrator 13 is also connected to the first vibrator 12. Similarly, it is used as an ultrasonic transmission element.

First, the ultrasonic microphone 31 is placed at a first reference point 31A that is a unit distance (for example, 100 mm) away from the first transducer 12, and the transmission control unit 21 transmits ultrasonic waves from the first transducer 12. The ultrasonic wave is transmitted from the first vibrator 12 in response to the instruction, picked up by the ultrasonic microphone 31, and the reception unit 22 generates a reception signal. As the generated received signal inputted to the arithmetic unit 23 obtains the first reference sound pressure P ₁₀ based on the received signal in the operation unit 23.

Next, in the same manner, the ultrasonic microphone 31 is placed at the second reference point 31B separated from the second transducer by a unit distance (for example, 100 mm), and the ultrasonic wave from the second transducer 13 is sent to the transmission control unit 21. To transmit ultrasonic waves from the second vibrator 13, picked up by the ultrasonic microphone 31, obtains a reception signal by the reception unit 22, and calculates a second reference sound pressure based on the reception signal by the calculation unit 23. determine the P _20.

Thereafter, the ultrasonic microphone 31 is moved to each point in the space to be measured, and an ultrasonic wave is transmitted from the first vibrator 12 for each point and picked up by the ultrasonic microphone 31, and the first measurement sound at that point is picked up. The pressure P _1i (i is the number of the measurement point) is obtained, and subsequently, an ultrasonic wave is transmitted from the second vibrator 13 and picked up by the ultrasonic microphone 31 and the second measurement sound pressure P _2i (i of the point). Is the number of the measurement point). This is repeated for each measurement point.

The arithmetic unit 23, a first reference sound pressure P ₁₀ obtained in this _manner, the second reference sound pressure P _20, the first measurement sound pressure P _1i and the second measurement sound pressure for each measurement point Based on P _2i , the ultrasonic attenuation rate r _i for each measurement point i is calculated according to the following equation.

In this way, the attenuation rate r _1i = P _1i / P ₁₀ when ultrasonic waves are emitted from the first transducer 12 on the transmission side during actual use and picked up by the ultrasonic microphone 31, and reception is performed during actual use. When the ultrasonic wave is emitted from the second vibrator 13 and picked up by the ultrasonic microphone 31, the attenuation rate r _2i = P _2i / P ₂₀ is obtained and multiplied by them to obtain the supersonic wave emitted from the first vibrator 12. The attenuation rate when the second transducer 13 receives the ultrasonic wave reflected by the reflector placed at the measurement point and returned to the second transducer 13 is obtained. By calculating the attenuation rate r _i for each measurement point, an effective ultrasonic intensity distribution in the measured space 10 is obtained. Actually, although the attenuation rate varies depending on the reflectance of the reflector, it is sufficient to obtain the relative ultrasonic intensity distribution in the measurement space, and the above measurement method is sufficient. Here, the calculation of the attenuation rate r _i based on the above equation (1) is shown, but this is an example. For example, in the case of dB expression, division is subtraction, multiplication is addition, and the apparent expression is different, but it is essentially the same as the above expression (1).

As in actual use, an ultrasonic wave is transmitted from the first vibrator 12 and received by the ultrasonic microphone 31 to obtain the attenuation rate r _1i . This time, an ultrasonic transmitter is used instead of the ultrasonic microphone 31. It is also conceivable that the ultrasonic transducer is transmitted at the measurement point i and received by the second vibrator 13 to obtain the attenuation rate r _2i , but the ultrasonic transmitter generally has a somewhat narrow directivity, and therefore If an ultrasonic transmitter is placed in place of the sonic microphone 31 to transmit ultrasonic waves, there is a risk of inaccurate measurement due to the directivity of the ultrasonic transmitter. On the other hand, some ultrasonic microphones 31 have sufficiently wide directivity, and the above measurement method using both the first and second vibrators 12 and 13 as ultrasonic transmission elements has higher accuracy. Can be measured.

  Next, a description will be given of a second embodiment in which a vehicle interior is a measurement target space.

  2 is a diagram showing the interior of the vehicle as viewed from the side, and FIG. 3 is a diagram of the interior of the vehicle as viewed from above. 2 and 3, the ultrasonic waves are shown in a plurality of beam shapes.

  A superstructure in which a first vibrator used as an ultrasonic sound source and a second vibrator used as an ultrasonic receiver are arranged side by side in a central ceiling portion of a driver seat and a passenger seat in the passenger compartment 100 and modularized. A sound wave module 101 is installed.

  The ultrasonic module 101 transmits ultrasonic waves in all directions in the vehicle interior, receives reflected ultrasonic waves, calculates the ultrasonic Doppler shift amount based on the received signal, determines the presence or absence of an intruder, When it is determined that there is an intruder, a warning sound is generated.

  Here, similarly to the first embodiment described above, not only the transducer used as the ultrasonic sound source but also the transducer originally used as the ultrasonic receiver is used as the ultrasonic sound source, and is the same as in the first embodiment. The attenuation rate is obtained for each measurement point in the passenger compartment 100 by the above measurement method. This attenuation factor is the product of the attenuation factor on the transmission side and the attenuation factor on the side that is essentially the reception side (see equation (1)). In the second embodiment shown here, a total of 16 ultrasonic microphones 31 are arranged side by side and four are arranged vertically, and 16 measurement points are simultaneously measured. The measurement is performed for all measurement points in the passenger compartment 100 while moving the 16 ultrasonic microphones 31 up and down and back and forth.

  FIG. 4 is a diagram showing the frequency distribution (A) of ultrasonic waves emitted from the first vibrator and the frequency distribution (B) of ultrasonic waves emitted from the second vibrator.

  Both have a large peak at a frequency of 40 kHz. 40kHz ultrasonic waves are used in the actual intruder detection scene. Therefore, here, only a narrow-band signal centered on 40 kHz is extracted by Fourier transform, the sound pressure of the extracted ultrasonic wave having a frequency of 40 kHz is obtained, and the ultrasonic intensity distribution in the vehicle interior is obtained. In this way, by extracting only a signal having a frequency that is actually used and obtaining an ultrasonic intensity distribution based on the signal having the frequency, an ultrasonic intensity distribution that matches the actual frequency can be obtained.

  FIG. 5 is a diagram showing the ultrasonic intensity distribution on the transmission side only in the vehicle interior, FIG. 6 is a diagram showing the ultrasonic intensity distribution on the side originally used for reception in the vehicle interior, and FIG. It is a figure which shows ultrasonic intensity distribution when the both sides are match | combined (namely, according to (1) Formula).

  The ultrasonic intensity distribution is considerably different between the transmitting side (FIG. 5) and the receiving side (FIG. 6), and it can be seen that FIG. 7, which integrates them, is different from FIGS.

  As described above, in each of the above-described embodiments, an effective ultrasonic intensity distribution in the measurement target space is obtained with high accuracy by transmitting ultrasonic waves from a transducer that is originally used as a receiving side. This ultrasonic intensity distribution can be reflected in an optimal design such as an intruder warning system and a layout in the measurement target space.

DESCRIPTION OF SYMBOLS 10 Measurement space 11 Wall surface 12, 13 Vibrator 14 Reflecting object 20 Processing circuit 21 Transmission control part 22 Reception part 23 Calculation part 24 Display part 25 Control part 31 Ultrasonic microphone 31A Reference point 100 Car interior 101 Ultrasonic module

Claims (3)

A first transducer that transmits ultrasonic waves into the measurement space; a second transducer that receives the ultrasonic waves reflected back within the measurement space and obtains reception signals; and An effective ultrasonic intensity distribution in the measurement space is measured when a mobile body detection device including a mobile body detection unit that detects the presence or absence of the mobile body in the measurement space is operated. An ultrasonic intensity distribution measuring method,
An ultrasonic wave is transmitted from the first transducer into the measurement space, and a first reference point that is a first reference distance away from the first transducer and a plurality of measurement points in the measurement space. An ultrasonic sensor is disposed, and the ultrasonic sensor receives ultrasonic waves. A first reference sound pressure that is a sound pressure of the first reference point and a plurality of first that is a sound pressure of each of the plurality of measurement points. A first step for obtaining a measured sound pressure of
An ultrasonic wave is transmitted from the second transducer into the measurement space, and a second reference point that is a second reference distance away from the second transducer and each of the plurality of measurement points in the measurement space. An ultrasonic sensor is disposed on the second sensor, and the ultrasonic sensor receives ultrasonic waves. The second reference sound pressure, which is the sound pressure of the second reference point, and a plurality of first pressures, each of which is the sound pressure of each of the plurality of measurement points. A second step for obtaining a measured sound pressure of 2;
A first ratio of each of the plurality of first measured sound pressures at each of the plurality of measurement points with respect to the first reference sound pressure obtained at the first step, and the first ratio obtained at the second step. A third step of obtaining an effective ultrasonic intensity distribution in the measurement target space based on a second ratio of each of the plurality of second measurement sound pressures at the plurality of measurement points with respect to a reference sound pressure of two; And an ultrasonic intensity distribution measuring method. The first step extracts a signal component resulting from the ultrasonic wave of the frequency to be measured from the received signal obtained by receiving the ultrasonic wave with the ultrasonic sensor, and based on the signal component, the first reference sound pressure and Obtaining the plurality of first measured sound pressures;
The second step extracts a signal component resulting from the ultrasonic wave of the frequency to be measured from the received signal obtained by receiving the ultrasonic wave with the ultrasonic sensor, and based on the signal component, the second reference sound pressure and The ultrasonic intensity distribution measuring method according to claim 1, wherein the step is a step of obtaining the plurality of second measured sound pressures.   3. The ultrasonic intensity distribution measuring method according to claim 1, wherein the ultrasonic intensity distribution measuring method uses a vehicle compartment as the measurement space.

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