JPH02170018A - Volume measuring method - Google Patents

Abstract

PURPOSE:To measure the volume of an object such as a human body in safety while the object is present in air by putting the object of measurement in a resonance space which has a communication part for the outside formed in part of a closed space, and applying a sound into the resonance space and measuring its resonance frequency. CONSTITUTION:A hole 2 which communicates with the outside is formed in one of the side walls of a box-shaped container 1 and the resonance space is formed in the container 1. In this space, the object M such as a human body is put, the space is isolated acoustically from the outside, and an acoustic oscillating means such as a speaker 5 sends the sound into the closed space in this state. The oscillated sound resonates at a frequency corresponding to variation in the capacity of the remaining space of the closed space excluding the capacity of the object M of measurement put inside. Here, this resonance frequency is measured and the capacity of the object M is calculated from the measured resonance frequency and the capacity of the closed space. Consequently, the object such as the human body need not be put in water and the capacity is measured accurately and safely in air.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for measuring the volume of an object, which has conventionally been difficult to measure. , and relates to a method of measuring accurately without causing pain to the object to be measured.

[Conventional technology]

There are several methods for measuring the body composition of the human body, such as body fat percentage, but in order to make measurements relatively accurate, one must first measure the volume of the human body and use that volume to determine a certain amount. A commonly used method is to calculate body composition using the following formula:

That is, the weight and volume of an object (hereinafter explained using a "human body" as an example) are determined, the density of the human body is calculated from the ratio, and the density of the human body is calculated from the calculated density using a formula obtained in advance through experiments. Methods of obtaining body composition such as fat percentage are used.

[Problem to be solved by the invention]

When carrying out the above method, it is possible to easily and accurately measure the weight of the object, but the human body volume is
There are many problems with any of the measurement methods currently in use.

A method of measuring the volume of a human body is to completely immerse the human body in a container full of water and measure the amount of water that overflows (usually by measuring the amount of water needed to refill the container after flooding). There are two methods: one method involves suspending a human body while immersing it in water, then determining buoyancy by comparing the measured underwater weight with the weight in the atmosphere, and then calculating the volume from that buoyancy. However, these methods require the human body to be completely submerged in the water, and in order to accurately measure the weight in the water, the lungs should be kept as low as possible to prevent the air in the lungs from acting as buoyancy when submerged in the water. The measurement subjects were forced into harsh conditions, as they had to take a breather and the measurement time took several tens of minutes, and there were also problems with the safety of the work.

[Means to solve the problem]

The present invention was constructed in view of the problems of the prior art shown above, and involves placing an object of unknown volume in a closed space of known volume, and creating resonance with the closed space by some means. This method takes advantage of the fact that there is a certain correspondence between changes in the residual volume of a closed space and changes in the resonant frequency. , is a method of measuring the volume of an object such as a human body while it is in the atmosphere by measuring the resonance frequency of the space.

[Effect]

A measurement object is placed in a space whose volume is known in advance, the space is acoustically isolated from the outside, and in this state, sound is oscillated in the closed space by an acoustic oscillation means such as a speaker. The oscillated sound resonates at a frequency that corresponds to the change in volume of the remaining space in the closed space excluding the volume of the measurement object stored inside, so the resonance frequency is measured and the measured resonance frequency and volume of the closed space are measured. Calculate the volume of the object based on.

[Example 1] Embodiments of the present invention will be described in detail below with reference to the drawings.

Since the present invention is constructed based on the following law, this law will be explained first.

When a hole is formed in a closed space to communicate the space with the outside, a resonance phenomenon occurs in the closed space. This phenomenon is known as Helmholz resonance or resonance box. That is, - For boat fishing, the volume of the enclosed space is ■. , the speed of sound is V, the cross-sectional area of the hole is S, and the length of the hole is C., the relationship with the resonance frequency W0 generated inside the closed space can be expressed by the following equation.

In the above relationship, the known volume■. When a measurement target of unknown volume ■8 is inserted into the closed space of , the resonant frequency W
0 changes (increases). This changed resonance frequency is WX
Then, WX can be expressed by the following formula.

From the above equations ■ and ■, we obtain the following 2〇.

That is, as is clear from the above formula 〇, the volume of the measurement object ■8
can be determined as a function of the volume of the closed space and the resonance frequency.

Further, considering the change in the atmospheric temperature of the space due to the temperature (body temperature) of the object, etc., the measurement object volume VX can be expressed by the following equation.

Here, vo is the sound velocity in the closed space before the measurement target is placed in it,
vX each indicates the sound velocity after the measurement target is included.

Also, the speed of sound in the atmosphere is expressed by the following formula.

Vo=331+0.6t, (m/5ec)...■
Note that t is the atmospheric temperature expressed in degrees Celsius (°C).

As is clear from the equations shown above, a measurement object such as a human being is placed in a closed space with a certain resonance hole, and the resonant frequency of the closed space before the measurement object is inserted and the measurement object is entered. The volume of the object to be measured can be determined using the above equation based on the resonance frequency of the closed space.

The present invention is a volume measurement method in which the above-mentioned law is applied to easily and accurately measure the volume of biological bodies, particularly human bodies, for which it has been extremely difficult to accurately measure volume using conventional methods.

Embodiments of the present invention will be specifically described below with reference to the drawings.

FIG. 1 schematically shows an apparatus for carrying out the method of the invention.

Reference numeral 1 denotes a container that houses the human body to be measured, and its constituent material uses a material with high acoustic insulation. In the illustrated configuration, the box-shaped container 1 is formed using a wooden board with a thickness of approximately 30T11. At the connection of each plate, packing or the like is interposed to ensure sufficient acoustic isolation at the joint.

Further, the size of the container is made so that the person M to be measured can enter it while standing. In the illustrated container,
Internal space depth 50cm, width 50cm, height 180cm
It is formed in m. 1a is the door of the container having this configuration.

Next, reference numeral 2 denotes a release hole formed in one of the side walls of the container 1 so as to communicate the inside of the container with the outside. 10cm,
The length is 30 cm, and the depth C is 5 cm.

3 is an acoustic oscillator that communicates with the sealed space inside the container and is acoustically isolated from the external space, and this acoustic oscillator includes an acoustic oscillator such as a speaker, and in some cases, an acoustic oscillator in addition to the acoustic oscillator. A sound receiving device such as a microphone is housed in the space. Reference numeral 4 denotes a volume measuring device connected to the device inside this acoustic oscillator.

FIG. 2 shows an example of the measurement method.

This method uses a speaker as an acoustic oscillator and uses the fact that the impedance of the speaker increases when resonance occurs to measure the resonant frequency without using an acoustic receiver such as a microphone.

This method oscillates sound while changing the oscillation sound frequency from a speaker, which is an acoustic oscillator, and measures the frequency at which the amplitude of the speaker terminal is maximum during the frequency change, and then measures the frequency at which resonance occurs. Then, the volume of the object is calculated from this frequency.

That is, when a person to be measured enters the closed space of the container 1,
When the door 1a is closed and the space is acoustically isolated from the outside, the speaker 5 emits sound. At this time, the oscillation acoustic frequency applied to the speaker 5 is sequentially changed by the variable frequency oscillator 8 via the sweep circuit 7 according to a command from the control circuit 6 .

On the other hand, the amplitude of the speaker terminal is constantly detected by the amplitude detector 9, and when the maximum amplitude is detected by the peak detector 1o, the control circuit 6 outputs a count command for the frequency at the maximum amplitude to the frequency counter 11, and Counter 11 counts the frequency at that point. Note that the amplitude of the speaker terminal is measured by detecting the alternating current voltage of the speaker terminal with an amplitude detector. Since the amplitude is maximum at the resonance point, the frequency F at the maximum amplitude is detected as shown in Fig. 3, the volume of the measurement object is calculated in the calculation circuit 12 based on this frequency F, and the result is displayed. Display on the container 13.

Next, we will specifically describe how to determine the volume of the measurement target.

First, the resonant frequency W in a state where no object to be measured is housed in the container 1. and container volume ■.

is determined in advance, and this value is stored in the memory mechanism of the measuring device 4. Next, calculation is made from the above-mentioned relational expression using the resonant frequency WX (ie, the frequency F at the maximum amplitude in FIG. 3) when the object to be measured with the unknown volume 8 is housed in the closed container 1.

[Example 2] In the case of more precise measurement including other conditions, the following method is used.

That is, the resonant frequency W in a state where no object to be measured is housed in the container 1. , Resonance frequency W of an object with known volume ■5, ,
Calculate the volume of the closed space using the formula below. seek.

■.

is as follows.

In other words, even if the volume of a closed space can be calculated from the measurement results by measuring each side of the space, such as a cube, it is not always possible to obtain an accurate volume by calculation due to measurement errors and distortions of the members that make up the walls. This is because it is impossible to obtain an accurate volume using this method if at least a portion of the wall surface constituting the closed space is a curved surface. On the other hand, the method of determining the volume using the above-mentioned formula allows the volume to be determined very accurately if the resolution of the device is increased.

From the above points, calculate the volume of the object to be measured using the following formula (■).

In addition, when operating the above method using a specific device, the following operation method can be considered.

First, the zero calibration switch is pressed with no object to be measured stored in the container 1, and the resonant frequency W0 is automatically measured with no object to be measured in the container 1, and the result is stored in the memory of the apparatus.

Next, an object with a known volume (for example, volume 50j2) is placed in the container 1, and in this state, the calibration switch is pressed. As a result, the resonant frequency W of the object of known volume
, , are stored in the memory, and thereafter the device calculates the volume of the resonant container by following the above procedure. Calculate. Subsequently, the object to be measured is placed in the container 1, and the volume of the object to be measured is determined by automatically performing the above procedure.

In addition, when the measurement target is an internal heat generating object such as a living body,
If the temperature of the object to be measured is different from room temperature, the resonant frequency will fluctuate due to a change in the speed of sound based on the temperature change in the closed space. Therefore, for more accurate measurements, it is necessary to take this temperature change into account.

The simplest method of temperature measurement is to place a temperature needle inside the container and use the measurement result as a correction value. However, the temperature distribution inside the container is not uniform, so
If the number of measurement points is small, there is a possibility that the accuracy of measuring the volume of the object will be reduced. Therefore, the inventors measured the average temperature inside the container by implementing the following method,
Good results were obtained.

That is, by placing a small speaker 5 on the ceiling of the container 1 and placing a microphone on the floor of the container opposite to the speaker placement surface, the time difference between the time of oscillation from the speaker and the time of reception from the microphone can be avoided. The average sound speed inside the container is determined by measuring the sound speed inside the container.

In the above method, the temperature when nothing is stored in the closed space is 1. If the temperature when the measurement target is stored is tX,
Fluctuations in resonance frequency due to temperature differences during measurement can be corrected using the following equation.

Note that when using temperature sensors (thermistors, etc.), it is possible to accurately measure the temperature distribution inside the container by adjusting the number and position of the sensors, and to obtain a relatively accurate average temperature from this temperature distribution. It is.

[Test 1] The inventors placed an object of known volume (25j2) in the container 1.
The volumes of these objects and their resonance frequencies were measured by sequentially storing them in the chamber. The results are shown in the table below.

Here, in the above table, column A shows the "volume of the object in the closed space" and column B shows the resonant frequency when the object is accommodated.

The above points are 1ogW and Ilog (Vo Vx)
When a graph of the logarithmic relationship was drawn, a good linear relationship with a slope of 1/2 was obtained.

[Test 2] The volume of each of six men and women was measured using the apparatus shown in FIG. 1. The measurement results are shown in the table below, but some of the subjects were tested using the conventional method (
As mentioned above, although it takes time to measure and causes considerable pain to the person to be measured, it has been confirmed that the measurement accuracy is relatively high.This result and the method of the present invention The results were almost the same as those obtained using the method, confirming the accuracy of the measurement method of the present invention.

Table 2 [Example 2] FIG. 4 shows a second embodiment.

This embodiment is configured to measure the resonant frequency by connecting a resonant frequency measuring circuit within the positive feedback loop of the feedback oscillator.

In this configuration, the speaker 5 is used as an acoustic oscillation source, and the sound is pick-amplified by the microphone 14 to form a feedback oscillator 15. In this configuration, the feedback oscillator 1
5 ends up causing acoustic oscillation at the resonant frequency, so that frequency can be directly counted by the frequency counter 11 as the resonant frequency.

[Example 3] FIG. 5 shows a third embodiment.

In this configuration, the excitation speaker 5 is regarded as an LC resonator,
A bridge type oscillator is constructed as shown in the figure.

Like the second embodiment, this circuit configuration also oscillates at the resonant frequency, so by counting the oscillation frequency with the frequency counter 11, the resonant frequency can be directly measured.

[Test 3] Applicants tested the relationship between the position of the speaker and the position of the resonance hole 2 in the container 1 shown in FIG. 1, and the resonance state.

In this case, it is desirable to set the positions of the speaker and the resonance hole so that the sound field inside the container 1 is uniform and the resonance inside the container at the time of resonance has a maximum resonant frequency below the generation of a standing wave. During the test, it was confirmed that the speaker could be placed on the side wall of container 1, on the ceiling B, or on the floor. However, in this test, the speaker 3 was placed on the ceiling of container 1, and The resonance hole 2 is fixed to the surface at three locations: the upper part of the side wall (indicated by the symbol A), the center part of the side wall (indicated by the symbol B), and the floor surface (indicated by the symbol C). The sound level in the height direction of the container was measured with the resonance hole placed in the container.

FIG. 7 shows the change in the sound level at each resonance hole position with no human body accommodated in the container, and FIG. 8 shows the change in the sound level with the human body accommodated in the container. As shown in FIG. 7, when no human body is housed, the configuration in which the resonance hole is placed at position B has an average sound level regardless of the position within the container, and good results were obtained. However, when the human body was stored, the sound level at position B varied greatly depending on the measurement position, as shown in FIG. On the other hand, when placed at position A, the sound level was almost the same regardless of the measured value.

Note that at position C, the sound level fluctuated greatly regardless of how the human body was stored, and good results could not be obtained. From the results of this test, it was found that the opening position of the resonance hole in the height direction of the container, as shown by position A, is preferably approximately at the position of the head of the person being measured. It was also confirmed that no problem would occur even if a plurality of resonance holes were provided or a plurality of speakers were provided.

Although the configuration of the present invention has been described above using the human body as an example of the measurement target, it is not intended to be limited to this, and the present invention can be applied to animals, various objects, etc. without limitation.

Furthermore, although the method of the present invention mainly measures the volume of the object to be measured, it is of course possible to obtain secondary data such as the fat percentage and specific gravity of the object to be measured based on the measured volume. It is.

〔effect〕

As explained in detail above, the present invention provides the following effects: When an object of unknown volume is placed in a closed space of known volume and resonance is caused in the closed space by some means,
Taking advantage of the fact that there is a certain correspondence between changes in the residual volume of a closed space and changes in the resonant frequency, by placing a measurement object such as a human body in the closed space and measuring the resonant frequency of that space. , it has become possible to measure the volume of an object such as a human body while it is still in the atmosphere, so it can be done safely, accurately, and quickly without causing pain to the living body being measured. The volume of the object to be measured can be measured in terms of time.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an apparatus for carrying out the method according to the present invention, FIG. 2 is a diagram showing an example of a circuit for volume measurement,
Fig. 3 is a diagram showing the relationship between the amplitude of the speaker terminal and the vibration frequency, Fig. 4 is a circuit diagram of a device for implementing the method of the second embodiment, and Fig. 5 is a diagram for implementing the method of the third embodiment. Figure 6 is a perspective view of the container showing the arrangement of the resonant holes relative to the container, and Figure 7 is the change in sound level in the height direction of the resonant container at each position in the resonant container when no human body is accommodated. FIG. 8 is a diagram showing changes in the sound level in the container height direction at each position of the resonant container when a human body is accommodated. 1... Container 2... Resonance hole 4... Volume measuring device 5... Speaker 11...
Frequency counter 14...Microphone 15
・・・Return J■ type oscillator Kakinakiki

Claims (6)

[Claims] (1) By forming a communication part with the outside in a part of the sealed space, this space is made into a resonant space, and a measuring object such as a human body is accommodated in this resonant space, and the object to be measured, such as a human body, is placed inside the resonant space in this state. A volume measuring method characterized by measuring a resonant frequency when a measuring object is accommodated by applying sound, and determining the volume of the measuring object based on this resonant frequency. (2) Use the device that applies the sound as a speaker, make the excitation frequency for this speaker variable, further measure the inductance at the speaker terminal, measure the frequency at the time when this inductance reaches the maximum, and calculate the resonance frequency. A volume measuring method according to claim (1), characterized in that: (3) A positive feedback loop of a feedback oscillator is formed by an oscillator that applies excitation current to the speaker and a microphone that measures the sound emitted from this speaker, and the frequency oscillated from this feedback oscillator resonates. The volume measuring method according to claim (1), characterized in that the volume is measured as a frequency. (4) A bridge-type oscillator is constructed by regarding a speaker for applying sound as a resonator, and the vibration frequency oscillated from the bridge-type oscillator is measured as a resonance frequency. Volume measurement method described in ). (5) Measure the temperature change in the resonant space when the measurement object is stored,
Claims (1) to (4) characterized in that the speed of sound in the resonant space under this changed temperature condition is determined and this speed of sound is used as a correction value when calculating the volume of the measurement object. Volume measurement method according to any of the paragraphs. (6) Receive oscillated sound at a known distance from an acoustic oscillation source such as a speaker, measure the time difference between the time of sound oscillation and reception, and determine the average temperature and/or sound speed in the resonant space from the time difference. The scope of claim No. (
Volume measurement method described in section 5).