KR20200072061A - Hand-held ultrasound camera with high spatial resolution - Google Patents

Abstract

The present invention relates to an ultrasonic camera used to diagnose the abnormality of a target facility by sensing a position of the generation of ultrasonic waves which are naturally radiated by an interoperation between components of a target facility such as an industrial facility, machinery or the like. A purpose of the present invention is to provide a portable high-resolution ultrasonic camera capable of obtaining a high-resolution measurement result while using fewer sensors than an existing beamforming method by using a functional beamforming method. Another purpose of the present invention is to provide a portable high-resolution ultrasonic camera capable of using fewer sensors than an existing ultrasonic camera while having high performance as well as reducing weight, thus improving economic feasibility and portability at the same time.

Description

Portable high-resolution ultrasound camera {Hand-held ultrasound camera with high spatial resolution}

The present invention relates to a portable high-resolution ultrasound camera, and more specifically, ultrasonics used to diagnose abnormalities of the target facility by detecting the position of the ultrasound radiation naturally emitted by the interaction between components in the target facility, such as industrial facilities and machinery. It's about the camera.

In the case of industrial equipment, especially high voltage applied parts, equipment, and devices, there is a high risk of damage or failure due to thermal factors generated by high power or physical factors such as vibration or shock generated during operation. When damage or breakdown occurs in these industrial facilities, the damage is enormous, so it is necessary to continuously check for any abnormality during operation of these industrial facilities.

It is known that when damage occurs in a target facility such as an industrial facility, machinery, etc., ultrasonic waves are naturally radiated by interaction between components at a corresponding location. Accordingly, conventionally, an ultrasonic camera device for diagnosing a target facility by detecting ultrasound waves emitted from the target facility has been developed and used. Korean Patent Registration No. 1167918 ("Ultra High Voltage Partial Discharge Diagnosis Device", 2012.07.17.), Korean Patent Registration No. 1477755 ("High-pressure panel, low-voltage panel, distribution panel equipped with ultrasonic-based arc and corona discharge monitoring and diagnosis system) , Motor control panel", 2014.12.23.), etc.

The ultrasonic camera for diagnosing such a conventional facility is generally configured to diagnose an abnormality at a specific point using a waveform measured using a single sensor or 2-3 sensors or a sound modulated according to an audible region. . However, in the case of such a prior art, since only a single point is measured when measuring once, there is a problem in that it takes a lot of time to inspect a wide workplace.

Accordingly, attempts have been made to apply a noise source location visualization method using a beamforming method using a plurality of sensor arrays to the ultrasound camera for facility diagnosis. The beam-forming technique refers to a technique of calculating the intensity distribution of a noise source in space through signal processing using a phase difference of a measurement signal according to a distance difference between a noise source and a measurement sensor, and estimating the location of the noise source according to its strength/weakness. In such a beam-forming technique, measurement precision is determined according to the number of sensors used. In general, it is known that the performance increases as the number of sensors is used.

As described above, since the performance of the beam-forming technique increases as the number of sensors increases, the ultrasonic camera to which the existing beam-forming technique is applied was manufactured to include more than 20 sensors. However, when such a large number of sensors is included, there is a problem in that the unit cost of the device is excessively increased. In addition, the existing ultrasonic camera is very heavy, and it is inconvenient for the operator to carry it, and there is also a problem that it is difficult to inspect for a long time.

1. Korean Patent Registration No. 1167918 ("Ultra-high pressure equipment partial discharge diagnosis device", 2012.07.17.) 2. Korean Patent Registration No. 1477755 ("High-pressure panel, low-voltage panel, distribution panel, motor control panel equipped with ultrasonic-based arc and corona discharge monitoring and diagnosis system", 2014.12.23.)

Therefore, the present invention has been devised to solve the problems of the prior art as described above, and the object of the present invention is to use a generalized beam-forming technique (functional beamforming method), which is less than the conventional beam-forming technique. It is to provide a portable high-resolution ultrasound camera that can obtain a high-resolution measurement results while using the sensor of the. Another object of the present invention is to provide a portable high-resolution ultrasound camera that can simultaneously improve economical efficiency and portability by reducing the weight as well as reducing the number of sensors compared to a conventional ultrasound camera.

The ultrasonic camera 100 of the present invention for achieving the above object, a plurality of sound pressure sensors 112 are disposed in a circular shape around the camera 111, the camera (111) by the camera ( 111) a measuring means (110) for acquiring an image in a direction facing and measuring a sound pressure of noise generated at a position facing the camera (111) by the sound pressure sensor (112); Display means (120) for superimposing the image acquired by the camera (111) and the sound pressure distribution measured by the sound pressure sensor (112); It may include.

At this time, the measurement means 110, the sound pressure power (P) and time delay (W) value measured by the plurality of sound pressure sensor 112 signal using a generalized beam-forming technique (functional beamforming method) A negative pressure distribution can be calculated by processing. More specifically, the measuring means 110 may calculate the beam power BP using the following equation.

(Here, BP: beam power, W: time delay scanning vector, C: cross-spectral matrix, P, which is calculated by C = PP ^H: sound pressure power matrix, ν: integer greater than 1)

In addition, the measurement means 110, the sound pressure sensor 112 may be made within a range of 5 to 10. The measurement means 110, a plurality of the sound pressure sensor 112, may be arranged in a low-density (sparse) arrangement arranged at intervals greater than 1/2 of the target signal wavelength to be measured. In addition, the measuring means 110, a plurality of the sound pressure sensor 112, the outer circumferential surface of the circle formed by the measurable range of the sound pressure sensor 112 and the outer circumferential surface of the camera 111 are to be disposed in contact with each other Can be.

In addition, the ultrasonic camera 100 is formed in a form extending in one direction, the measuring means 110 is formed at one end, and the main body 151 and the user gripping the display means 120 are formed at the other end. A body 150 including a gripping portion 152 extending downwardly from the main body portion 151 to be possible; It may further include.

At this time, the body 150, the measuring means 110 and the display means 120 to receive the user input for the operation ON / OFF control, the user grip including a button in a form that allows the user to hold the 152 ) May further include an input unit 153 formed on the.

According to the present invention, there is an effect of using a generalized beam-forming technique (functional beamforming method) to obtain a high-resolution measurement result while using fewer sensors than the conventional beam-forming technique. In particular, according to the present invention, by providing an optimized number and arrangement of sensors, there is a great effect of realizing a low-density arrangement and obtaining high-resolution performance.

In addition, according to the present invention, as well as reducing the number of sensors compared to the conventional ultrasonic camera has a high performance, and also reduces the weight and volume, there is a great effect that can simultaneously improve the economic efficiency and portability. Accordingly, there is also an effect of solving a problem that a user who performs a task of diagnosing a target facility using an ultrasonic camera has difficulty in moving or prolonged diagnosis work due to the weight of the camera.

1 is an embodiment of the ultrasonic camera of the present invention.
2 illustrates the principle of the beam-forming technique.
3 is an example of sensor placement of a conventional ultrasound camera using a classic beam-forming technique.
4 is a comparison of a classic beam-forming technique and a generalized beam-forming technique.
5 is an example of sensor placement of an ultrasonic camera of the present invention using a generalized beam-forming technique.
6 is a comparison of the sensor arrangement of the ultrasonic camera of the prior art and the present invention.
7 and 8 is a comparison of the measurement using the ultrasonic camera of the prior art and the present invention.

Hereinafter, a portable high-resolution ultrasound camera according to the present invention having the above-described configuration will be described in detail with reference to the accompanying drawings.

Configuration of the ultrasonic camera of the present invention

1 shows an embodiment of the ultrasonic camera of the present invention. The ultrasonic camera 100 of the present invention basically includes a measuring means 110 for measuring image and sound pressure, and a display means 120 for visually displaying the measurement result, as shown in FIG. 1(A). In addition, the ultrasonic camera 100 is also integrated with the measuring means 110 and the display means 120, as shown in Figure 1 (A), the body 150 to facilitate the user to carry and use. It may further include. The details of each part are as follows.

The measuring means 110 includes a camera 111 and a plurality of sound pressure sensors 112. At this time, the camera 111 serves to acquire an image in a direction facing the camera 111, and the sound pressure sensor 112 serves to measure the sound pressure of noise generated at a position facing the camera 111. Do it. Particularly, in the present invention, a plurality of sound pressure sensors 112 are arranged in a circle around the camera 111 as shown in FIG. 1(B), which has a very important technical meaning in the present invention. The technical meaning will be described in more detail in the principle description of the ultrasonic camera of the present invention.

The display means 120 superimposes the image acquired by the camera 111 and the sound pressure distribution measured by the sound pressure sensor 112, as shown in FIG. 1(C). Therefore, the user can intuitively and easily recognize the noise generation location through the image and sound pressure distribution overlapping screen displayed on the display means 120.

The body 150 is configured to increase user convenience by integrating the measuring means 110 and the display means 120 as described above. The body 150 may include a body part 151 formed in a form extending in one direction and a gripping part 152 extending below the body part 151. The measuring means 110 is formed at one end of the main body 151 and the display means 120 is formed at the other end, so that the measuring means 110 and the display means 120 can be integrated. have. It was previously described that the measuring means 110 measures the image and sound pressure, and the display means 120 outputs and displays them. In practice, a power supply (battery) for supplying power to a calculation circuit, wiring, or power for such signal processing It is natural that more back is needed. The main body portion 151 may be configured to include components such as an operation circuit, wiring, and power therein. Meanwhile, the gripping portion 152 is a portion formed to enable user gripping, that is, a configuration for improving user convenience. At this time, on the gripping part 152, an input unit 153 serving to receive user input for controlling operation ON/OFF of the measuring means 110 and the display means 120 is further formed, thereby further enhancing user convenience. Can improve. The input unit 153 may be formed in a button form as illustrated in FIG. 1, and of course, any other form may be used as long as it can receive user input. Using the input unit 153, the measurement means 110 and the display means 120 are turned ON only when the user desires, and measurement and display are performed. When not desired, the measurement is performed by the ultrasonic camera 100 by turning it OFF. It can save more power.

Measuring principle of the ultrasonic camera of the present invention

Hereinafter, the technical principle of the arrangement of the sound pressure sensor 112 of the present invention and the measuring principle of the ultrasonic camera of the present invention will be described in more detail.

First, the beam-forming technique is used in the ultrasonic camera 100 of the present invention. As described above, the beam-forming technique calculates the intensity distribution of a noise source in space through signal processing using a phase difference of a measurement signal according to a distance difference between a noise source and a measurement sensor, and estimates the location of the noise source according to its strength/weakness Refers to the technique. 2 is a view for explaining the principle of the beam-forming technique. As shown in FIG. 2, it is assumed that M sound pressure sensors are arranged on the x-axis in a situation in which an acoustic signal having a wavelength of λ is traveling in a direction having an inclination angle of θ _s with respect to the y-axis. At this time, the sound pressure power (P ₁ , P ₂ , …, P _M ) is measured at each sound pressure sensor, and the time delay (W ₁ , W ₂ , …, W _M due to the position of each sound pressure sensor is different from each other) ) Occurs. When these values are added and averaged, a main lobe is formed when θ is θ _s as shown in the graph shown at the bottom of FIG. 2, and a side lobe having a relatively much smaller value around it. Are formed. That is, the beam power (BP) can be calculated by using Equation 1 below using the sound pressure power (P) and time delay (more precisely, the time delay scan vector, W) values measured using a plurality of sound pressure sensors. , The point where the beam power BP becomes the maximum according to θ becomes the direction in which the sound proceeds, that is, θ _s , so that the position of the sound source can be located.

(식 1)

(Equation 1)

In such a beam-forming technique, measurement precision is determined according to the number of sensors used. In general, it is known that the performance increases as the number of sensors is used. As described above, when the classical beam-forming technique is used, the precision of measurement increases as the number of sensors increases. In addition, it is well known that ideally, the most accurate measurement can be made when the distance between each sensor is within 1/2 of the target signal wavelength (λ) to be measured. However, in reality, it is difficult to deploy the sensor to meet these conditions. In the case of noise targeted by an ultrasonic camera, if the frequency of the target signal is approximately 40 kHz and the speed of sound in the atmosphere is approximately 340 m/s, the half of the target signal wavelength is approximately 4 mm. Becomes. That is, in order to accurately measure the location of a noise source having a frequency of about 40 kHz, the sensors must be closely arranged at 4 mm intervals. In this case, the device price is too high, making it difficult to realistically manufacture the device with these specifications. In order to solve this problem, by arranging the sensors at an appropriately wide interval but randomly arranging, the main lobe can be strengthened, but an effect of canceling noise, which is an unnecessary or wrong signal, can be obtained.

Fig. 3 shows an example of the sensor arrangement of a conventional ultrasonic camera using this classic beam-forming technique. As shown in FIG. 3, in a conventional ultrasonic camera using a classic beam-forming technique, a large number of sound pressure sensors (generally 20 or more) are randomly disposed in a fairly large area around the camera. It was done. However, as described above, the conventional ultrasonic camera has a number of sensors, a device volume, and a weight that is too large, and thus, various problems such as an increase in device price, a decrease in user portability, and convenience have been pointed out.

In the present invention, a generalized beamforming method is used instead of the classical beamforming technique. In the classical beam-forming technique, beam power BP is calculated through Equation 1, but in the generalized beam-forming technique, beam power BP is calculated through Equation 2 below.

(식 2)

(Equation 2)

If the value of ν in Equation 2 is 1, it becomes the same as Equation 1, that is, the result is the same as the classical beam-forming technique. However, when the value of ν is not 1, the following difference occurs. It is well known that the mutual spectral matrix C (= PP ^H ) made of sound source power P directly affects the size of the main lobe, and the time delayed scan vector W directly affects the distribution and size of the side lobes. At this time, the size of W always has a value between 0 and 1 (ie, 0 ≤ W <1). In Equation 2, regardless of the value of ν, C is the square of ν and 1/ν squared, resulting in C again, whereas W is the ν squared calculation, so as the value of ν increases, the value of ν squared of W Becomes smaller and smaller. Physically explaining this, when calculating the beam power BP using Equation 2, the larger the value of ν, the less the main lobe, while the smaller the side lobe.

4 is a comparison of the beam power graphs calculated by each of these classic beamforming techniques and generalized beamforming techniques. As shown in FIG. 4(A), when ν=1, the classic beam-forming technique graph and the generalized beam-forming technique graph appear completely the same. However, as shown in FIG. 4(B), when ν=10 has a value greater than 1, the classic beam-forming technique graph is significantly larger than that in FIG. 4(A) and has many side lobes. , In the generalized beam-forming technique graph, it can be seen that all side lobes are removed, and the main lobe also forms a sharper peak. As shown in FIG. 4(C), when ν=100 is made larger, the main lobe becomes sharper even when compared with the graph of FIG. 4(B), that is, the larger the ν value, the more accurate the peak position is. It can also be seen that it can be clearly drawn.

In the measurement means 110 of the present invention, the sound pressure power (P) and time delay (W) values measured by the plurality of sound pressure sensors 112 are signaled using a generalized functional beamforming method. It is made to calculate the sound pressure distribution by processing. More specifically, the measuring means 110 is made to calculate the beam power BP using the above equation 2, that is, the following equation.

(Here, BP: beam power, W: time delay scanning vector, C: cross-spectral matrix, P, which is calculated by C = PP ^H: sound pressure power matrix, ν: integer greater than 1)

As can be seen intuitively from FIG. 4 alone, the measurement means 110 of the present invention uses a generalized beam-forming technique rather than a classic beam-forming technique, dramatically reducing side lobe effects and reducing the main lobe position. It can be found much more clearly, that is, the location of the noise source can be accurately detected.

On the other hand, as described above, in the beam-forming technique, as the number of sensors for measuring sound pressure power increases, the performance improves, and ideally, the sensors are preferably disposed within 1/2 of the target signal wavelength to be measured. However, as described above, the close arrangement of the sensor may improve performance, but it is a factor that increases device price, volume, and weight, which makes it difficult to apply realistically.

This problem is the same in the generalized beam-forming technique, but in the present invention, the problem is solved through a circular arrangement of sensors (as shown in FIG. 1 and the like). 5 shows an example of the sensor arrangement of the ultrasonic camera of the present invention using a generalized beam-forming technique, as shown in FIG. 5, in the present invention, a plurality of the sound pressure sensors 112 are the camera 111 ) To be arranged in a circle.

In FIG. 5, the measurable range of the sound pressure sensor 112 is indicated by a circle of a dotted line surrounding the sound pressure sensor 112. At this time, in the present invention, the plurality of sound pressure sensors 112 are arranged in a low density (sparse) arrangement arranged at intervals greater than 1/2 of the target signal wavelength to be measured. At this time, if the measurable range of the sound pressure sensor 112 overlaps with the camera 111, the corresponding portion may be a dead zone, and when the sound pressure sensor 112 is too far from the camera 111, the sound pressure The area of the sensor 112 is unnecessarily widened. In consideration of these matters, as shown in FIG. 5, the measuring means 110 includes a plurality of the sound pressure sensors 112, the outer circumferential surface of the circle formed by the measurable range of the sound pressure sensor 112 and the camera It is preferable that the outer circumferential surfaces of (111) are made to be disposed at positions in contact with each other.

Conventionally, even if the sensors are in a low-density arrangement, in order to sufficiently improve performance, a large number of sensors have to be randomly arranged on a large area, which has been a factor of increasing the number of sensors, the volume of the device, and the weight. However, in the present invention, as shown in FIG. 5, the arrangement of the sound pressure sensors 112 surrounding the camera 111 need only be formed in one row. Therefore, according to the present invention, it is possible to dramatically reduce the number of sensors required to obtain a desired level of sufficient performance as compared to the prior art. In addition, since the area for sensor placement itself is much reduced, as a result, the volume and weight of the device can be dramatically reduced compared to the prior art.

From the experiments conducted for the present invention, it has been found that the sound pressure sensors 112 need only be arranged in a circular shape. At this time, the sound pressure sensors 112 are required to satisfy the condition that they form a “circle”. It has been found that the number of sensors 112 should be more than four. Therefore, in the present invention, the number of the sound pressure sensor 112 included in the measuring means 110 is preferably 5 or more.

On the other hand, as described above, as the number of the sound pressure sensors 112 increases, the measurement performance is improved, of course, when the number of the sound pressure sensors 112 increases, the device price increases due to the increase in the number of sensors. In addition to the problems, an increase in calculation time and load also occurs. If the calculation time and load increase excessively, it is necessary to use a high-performance computing circuit with good calculation performance, which in turn causes a rise in device price. In view of this, in the present invention, it is preferable that the number of the sound pressure sensors 112 is not too large. Considering that 20 or more sensors have been used in the case of the conventional ultrasonic camera, in the present invention, the number of the sound pressure sensors 112 included in the measuring means 110 may be set to 10 or less.

More specifically, from a series of experiments conducted for the present invention, empirically, when the number of the sound pressure sensors 112 is 7, it is possible to obtain sufficiently high-resolution measurement results, and at the same time, the calculation time and load are appropriate. It was confirmed. In consideration of this point, in the present invention, as an optimal embodiment, the number of the sound pressure sensors 112 is shown as seven, but of course, the present invention is not limited thereby. That is, in conclusion, in the present invention, the measuring means 110, it is preferable that the sound pressure sensor 112 is made within a range of 5 to 10.

6 is a view comparing the arrangement of the sensor of the ultrasonic camera of the prior art and the present invention. Fig. 6(A) shows the sensor arrangement of the conventional ultrasonic camera as in Fig. 3, and Fig. 6(B) shows the sensor arrangement of the ultrasonic camera of the present invention as in Fig. 5, respectively, but the same scale for both cases. Was applied. 6(A) and 6(B), it can be confirmed that the same scale was applied as the cameras had the same diameter.

As can be seen intuitively when comparing FIGS. 6A and 6B, according to the present invention, the number of sensors can be drastically reduced compared to the prior art. In addition, as described above, according to the present invention, since the sensor arrays arranged in a circle surrounding the camera need only be formed in one row, it is confirmed that the size of the measuring means can be drastically reduced compared to the prior art.

Measurement results of the ultrasonic camera of the present invention

7 and 8 compare the measurement results using the ultrasonic camera of the prior art and the present invention.

7 is a measurement result when a noise source exists at a position where θ=0ㅀ and φ=0ㅀ in a spherical coordinate system, and FIG. 7(A) is a conventional ultrasonic camera, that is, a sound pressure distribution using a classic beam-forming technique As a result of the measurement, FIG. 7(B) shows the results of measuring the sound pressure distribution using the ultrasonic camera of the present invention, that is, the generalized beam-forming technique. As shown in FIG. 7(A), since the influence of the side lobe is considerably large in the related art, it is difficult to accurately determine the location of the noise source only with the magnitude of sound pressure. You can see that you can do it. On the other hand, as shown in Figure 7 (B), in the case of the present invention, by effectively suppressing the side lobe, it can be clearly confirmed that the position of the noise source is significantly and accurately compared to Figure 7 (A).

8 is a measurement result when a noise source exists at a position of θ=150ㅀ and φ=-40ㅀ in a spherical coordinate system. As in FIG. 7, FIG. 8(A) is a conventional ultrasonic camera, that is, a classic beam- As a result of measuring the sound pressure distribution using the shaping technique, FIG. 8(B) shows the results of measuring the sound pressure distribution using the ultrasonic camera of the present invention, that is, the generalized beam-forming technique. As shown in Fig. 8(A), the influence of the side lobe is too strong in the conventional case, so in this case, the location of the noise source is quite difficult even if the shape of the sound pressure distribution is actually considered. On the other hand, as shown in Fig. 8(B), in the case of the present invention, the side lobes that obscure the noise source position are completely suppressed, and accordingly, only the main lobe that forms a sharp peak appears in the sound pressure distribution result. Unlike, it is very easy to locate the noise source.

The present invention is not limited to the above-described embodiments, and of course, the scope of application is diverse, and anyone who has ordinary knowledge in the field to which the present invention pertains without departing from the gist of the present invention as claimed in the claims. Of course, various modifications are possible.

100: ultrasonic camera 110: measuring means
111: camera 112: sound pressure sensor
120: display means
150: body 151: body portion
152: gripping unit 153: input unit

Claims (8)

A plurality of sound pressure sensors 112 are disposed in a circular shape around the camera 111 to obtain an image in the direction that the camera 111 is directed by the camera 111 and the sound pressure sensor 112 to Measuring means for measuring the sound pressure of the noise generated at a position facing the camera 111 (110);
Display means (120) for superimposing the image acquired by the camera (111) and the sound pressure distribution measured by the sound pressure sensor (112);
An ultrasound camera comprising a.
The method of claim 1, wherein the measuring means 110,
Characterized in that the sound pressure distribution is calculated by signal processing the sound pressure power (P) and time delay (W) values measured by the plurality of sound pressure sensors 112 using a generalized functional beamforming method Ultrasound camera.
According to claim 2, The measuring means 110,
An ultrasonic camera characterized in that the beam power (BP) is calculated using the following equation.

(Here, BP: beam power, W: time delay scanning vector, C: cross-spectral matrix, P, which is calculated by C = PP ^H: sound pressure power matrix, ν: integer greater than 1)
The method of claim 1, wherein the measuring means 110,
The ultrasonic camera, characterized in that the sound pressure sensor 112 is made within a range of 5 to 10.
The method of claim 4, wherein the measuring means 110,
An ultrasonic camera, characterized in that a plurality of the sound pressure sensors 112 are arranged in a sparse arrangement arranged at intervals greater than 1/2 of the target signal wavelength to be measured.
The method of claim 4, wherein the measuring means 110,
The ultrasonic camera, characterized in that a plurality of the sound pressure sensor 112, the outer peripheral surface of the circle formed by the measurable range of the negative pressure sensor 112 and the outer peripheral surface of the camera 111 are in contact with each other.
The method of claim 1, wherein the ultrasound camera 100,
It is formed in a form extending in one direction, the measuring means 110 is formed at one end and the display means 120 is formed at the other end of the main body portion 151 and the main body portion 151 to enable user gripping. Body 150 including a grip portion 152 extending to;
An ultrasound camera further comprising a.
The method of claim 7, wherein the body 150,
An input unit 153 formed on the gripping unit 152 in a form capable of user input including a button so as to receive a user input for operating ON/OFF control of the measuring means 110 and the display means 120 An ultrasound camera further comprising a.

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