KR20200128902A - Detecting system for measuring operating sounds of washing machine and detecting method for noise defect there of - Google Patents

Abstract

The present invention relates to a device for detecting a noise defect phenomenon occurring inside a washing machine when the washing machine is operated and a detection system, wherein the detection system can measure noise generated inside the washing machine by inserting a measuring device into a rotating washing tub, and can determine whether the noise is defective through a signal processing system. An operating sound measuring device according to an embodiment of the present invention is attached to the washing tub of the washing machine to measure the operating sound of the washing machine, and includes: a body unit including a coupling structure or material attached to the inside of the washing tub; and a microphone unit that is positioned inside the body unit and generates a measurement signal by measuring an internal operating sound when the washing machine is operated.

Description

Washing machine noise defect detection system and noise defect detection method using the same {DETECTING SYSTEM FOR MEASURING OPERATING SOUNDS OF WASHING MACHINE AND DETECTING METHOD FOR NOISE DEFECT THERE OF}

The present invention relates to an apparatus and a detection system for detecting a noise defect phenomenon occurring inside a washing machine when the washing machine is operated, and measuring noise generated inside the washing machine by inserting a measuring device into a rotating washing tub, and using a signal processing system. It relates to a detection system capable of determining whether a washing machine is defective due to the noise.

Strict quality control in the production of washing machines, like the characteristics of other manufacturing industries, is a very important process not only to improve product reliability but also to minimize customer complaints. In a manufacturing process that has to detect even a few defects among tens of thousands of products, an effective and efficient defect detection method maintains high quality, increases production efficiency, and consequently has an economic effect of reducing manufacturing costs.

In actual field, various inspection methods are applied in the production line according to the type of defect in order to detect defects occurring in the process of mass production of washing machines. Among them, defects in quality due to part interference due to defective assembly, joints and malfunctions due to missing residues, and defective shape of assembly parts correspond to the types of defects that can detect normal and abnormality from operation sounds generated when the washing machine is operated. do. So, in the existing method, power was supplied to the washing machine in the final process of the manufacturing line, operated in a predetermined mode, and the defect was detected by a sensual method while the worker heard the sound.

However, such a method has a problem that not only makes it difficult for the operator to make an accurate determination due to various noises generated in other processes of the manufacturing line, but also causes the defect detection rate to be significantly lowered because the operator cannot hear the sound after concentrating for a long time.

In the conventional case, most of the technology related to noise of a washing machine is a technology for a device that reduces noise. Korean Patent No. 10-1648109 relates to a washing machine for securing space for laundry capacity and improving noise, extending the height of the undercase, reducing the height of the drum and plate, extending the height of the shaft pulley, and reducing the length of the coupling. , As the power transmission assembly consisting of the assembly of these parts processed in a method by reducing the overall length of the coupling, the overall length of the cleat spring, and the reduction of the overall length of the boss is built in the inner center of the washing machine, the entire washing machine In addition to reducing the load, it is possible to increase the capacity of the laundry, block noise such as a crash sound caused when the washing machine is operated, and secure a space for the laundry capacity that can secure a space for increasing the capacity of the laundry, and a washing machine for noise improvement. Provides.

In the case of the present invention, since it is configured to measure the operation sound inside the washing machine and determine whether the washing machine is abnormal or defective from the measured operation sound, it is different from the conventional technology. There is a need to develop a technology that can determine whether a washing machine is defective.

Korean Patent Registration No. 10-1648109

An object of the present invention is to provide an operating sound measuring device capable of measuring an operating sound inside a washing machine and determining whether a washing machine is abnormal or defective from the measured operating sound, and a defect inspection system including the same.

The technical problems to be solved by the invention are not limited to the technical problems mentioned above, and other technical problems that are not mentioned will be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. I will be able to.

The operating sound measuring apparatus according to an embodiment of the present invention includes: a body part attached in a washing tub of a washing machine to measure the operation sound of the washing machine, and including a coupling structure or material attached to the washing tub; And a microphone unit positioned inside the body unit and configured to generate a measurement signal by measuring an internal operation sound when the washing machine is operated.

The operating sound measuring apparatus according to an embodiment of the present invention includes: a body portion having an unbalanced mass distribution of an elastic material, which is input into a washing tub of a washing machine to measure the operating sound of the washing machine; And a microphone unit positioned inside the body unit and configured to generate a measurement signal by measuring an internal operation sound when the washing machine is operated. Here, the body portion may be set to have an unbalanced mass distribution by arranging the microphone portion and the wireless transmission portion respectively at preset positions.

On the other hand, the operating sound measuring apparatus according to an embodiment of the present invention is located inside the body, a wireless transmission unit that transmits the measurement signal to the outside by wireless communication or a storage medium storing the measurement signal. It may contain more.

A defect inspection system according to an embodiment of the present invention includes: an operating sound measuring device for generating a measurement signal by measuring the operating sound of the washing machine in a washing tub of the washing machine; And a signal analysis device that analyzes the measurement signal to determine whether the washing machine is abnormal. Here, the signal analysis device compares the waveform in the frequency domain of the measured measurement signal with a preset frequency waveform database, or compares the waveform in the time domain of the measured measurement signal with a preset time waveform database, and the washing machine It is possible to judge whether or not is abnormal.

In addition, the solution to the above-described problem does not enumerate all the features of the present invention. Various features of the present invention and advantages and effects thereof may be understood in more detail with reference to the following specific embodiments.

The operating sound measuring apparatus and the defect inspection system including the same according to an embodiment of the present invention measure the operating sound inside the washing machine, thus minimizing the effect of external noise, etc. to clearly measure the operating sound and abnormal sound caused by the fault. can do. In addition, since separate facilities or additional processes such as a soundproof tunnel, a noise separation device, and a directional microphone are not required, cost reduction and production increase effects can be obtained.

In the working sound measuring device and the defect inspection system including the same according to an embodiment of the present invention, since the working sound measuring device located inside the washing machine transmits the measurement signal to the signal processing device located outside by using a wireless signal, It is easy and fast to collect measurement signals, and it is possible to quickly determine whether the washing machine to be inspected is defective.

1 is a schematic diagram showing a defect inspection system according to an embodiment of the present invention.
2 is a block diagram showing a working sound measuring apparatus and a signal analysis apparatus according to an embodiment of the present invention.
3 is a schematic diagram showing the operation of the first step (S10) of the defect inspection system according to an embodiment of the present invention.
Figure 4 is a schematic diagram showing the operation of the second step (S20) of the defect inspection system according to an embodiment of the present invention.
5 is a schematic diagram showing the operation of the third step (S30) of the defect inspection system according to an embodiment of the present invention.
6 is an example obtained by converting a cepstrum performed to detect a defect linked to a motor rotation frequency among defective patterns of a washing machine.
Figure 7 is the first step for calculating the envelope, (a) is obtained by Fourier transform of the time signal x(t), and it is converted to a positive value while preserving the energy of the negative region (b). to be.
FIG. 8 is a method of calculating an envelope, and it is schematically illustrated that a signal of x(t), which is obtained by combining two or more frequencies, can be separated from c(t) and m(t) using a filter.
FIG. 9 is a diagram illustrating a signal showing an envelope phenomenon by applying a specific filter to the actually measured sound pressure signal (noise).
FIG. 10 shows the envelope calculated using the signal of FIG. 9 by comparing the results of the normal product and the defective product, and shows a significant difference in the value of the motor rotation frequency of 12 Hz.
11 is a flow chart showing a method of detecting a noise defect using a washing machine operation sound measuring device.
12 is a flow chart showing in more detail the fourth step (S400), the sixth step (S600) and the ninth step (S900) in the noise defect detection method using the washing machine operating sound measuring device of FIG.
13 is a graph showing collected raw data in a first step (S100) in the method for detecting a noise defect using the washing machine operation sound measuring device of FIG. 11.
14 is a graph in which the background noise of the second step (S200) is removed in the method for detecting a noise defect using the washing machine operation sound measuring device of FIG. 11.
15 is a graph showing a bandpass filter region of 2.5k~4.0k Hz for detecting noise defects
FIG. 16 is a graph of FIG. 15, which is a graph obtained by analyzing the quartosis of the sixth step (S600) in FIG. 12, and calculates the quartosis of a time signal obtained by bandpass filtering the previously set failure frequency band.
17 is a spectrogram filtered by the 1.4k ~ 1.6k Hz bandpass filter of the fourth step (S400) in the noise defect detection method using the washing machine operation sound measuring device of FIG. 12, and characteristics of defects that can be detected by the envelope And is the step of selecting the frequency band in question.
FIG. 18 is a graph of FIG. 17, which is a graph of the envelope analysis of the sixth step (S600) of FIG. 12, where (A) is a time signal showing the characteristics of a defect extracted by the previously applied band pass filter, and (B) is ( The envelope is calculated with the filtered time signal of A) and compared with normal and defective.
FIG. 19 is a graph showing the frequency range of 3.4k to 3.9k Hz including the noise defect of the fourth step (S400) in the method for detecting noise defects using the washing machine operation sound measuring device of FIG. 12, and unlike the spectrogram, It is a spectrum showing the frequency characteristics over time.
20 is a graph of FIG. 19, which is a graph of the envelope analysis of the sixth step (S600) of FIG. 12.
21 is a graph showing a frequency range of 4.0k to 7.0k Hz including the noise defect of the fourth step (S400) in the noise defect detection method using the washing machine operation sound measuring device of FIG. 12.
22 is a graph of FIG. 21, which is a graph obtained by analyzing the envelope of the sixth step (S600) of FIG. 12.
23 is a graph of a cepstrum analysis of the sixth step (S600) of FIG. 12 as the graph of FIG. 21.
24 is a flow chart showing a procedure for calculating a cepstrum in frequency domain analysis.
25 is a flowchart showing an envelope operation procedure in time domain analysis.
FIG. 26 is a graph for explaining a duration of maintaining a value having a large quartosis in step S600 of FIG. 12.

The terms used in the present specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected from general terms that are currently widely used while considering functions in the present invention, but this may vary depending on the intention or precedent of a technician working in the field, the emergence of new technologies, and the like. Therefore, the terms used in the present invention should be defined based on the meaning of the term and the overall contents of the present invention, not a simple name of the term.

When a part of the specification is said to "include" a certain element, it means that other elements may be further included rather than excluding other elements unless specifically stated to the contrary.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art may easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

Specific matters, including the problems to be solved, means for solving the problems, and effects of the present invention, are included in the following examples and drawings. Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings.

1 is a schematic diagram showing a defect inspection system according to an embodiment of the present invention.

Referring to FIG. 1, the defect inspection system according to an embodiment of the present invention may include a working sound measuring device 100 and a signal analyzing device 200.

Hereinafter, a defect inspection system according to an embodiment of the present invention will be described with reference to FIG. 1.

The operating sound measuring device 100 may be located inside the washing tub 2 of the washing machine 1 and measures the operating sound of the washing machine 1 inside the washing tub 2 when the washing machine 1 is operated. can do. That is, the inspector may insert the operating sound measuring device 100 into the washing machine 1 in order to check the operating state of the washing machine 1 and determine whether it is defective, and the operating sound measuring device 100 The washing machine 1 may be operated while the washing machine 1 is located inside the washing machine 1. At this time, since the operating sound measuring device 100 measures the operating sound inside the washing machine 1, it is possible to measure only the pure operating sound of the washing machine without external noise.

Thereafter, the operating sound measuring apparatus 100 may generate a measurement signal according to the measurement result, and transmit the generated measurement signal to the outside through wireless communication. Accordingly, it is possible to easily receive the measurement signal of the operating sound measuring apparatus 100 from the outside, and by using this, it is possible to determine whether the washing machine 1 is abnormal or defective.

Depending on the embodiment, instead of outputting to the outside using wireless communication, the operating sound measuring device 100 stores the measurement signal in an internal storage medium (not shown), and then the inspector It is also possible to collect 100 and collect measurement signals directly from the storage medium.

Meanwhile, referring to FIG. 2(a), the operating sound measuring apparatus 100 according to an embodiment of the present invention may include a body portion 110, a microphone portion 120, and a wireless transmission portion 130. .

The body unit 110 may include the microphone unit 120 and the wireless transmission unit 130 therein, and is applied to the microphone unit 120 and the wireless transmission unit 130 when the washing machine 1 is operated. Losing can absorb and protect impact.

Depending on the embodiment, the operating sound measuring device 100 is put into the interior of the washing tub 2 and can be moved inside according to an operation of the washing machine 1 such as rotation. That is, the body part 110 may be implemented as an elastic body such as rubber or plastic so that the operating sound measuring device 100 can operate like an unbalanced mass for defect inspection of the washing machine 1, and the shape or density It can be designed to have an unbalanced mass distribution according to the like. That is, the unbalanced mass serves as laundry in the process of checking the operating state of the washing machine 1. The operator checks whether or not the washing machine 1 is operated in a state in which the unbalanced mass is put into the washing tub 2. Here, it is possible to implement an unbalanced mass distribution by utilizing the arrangement of the microphone unit 120 and the wireless transmission unit 130 located inside the body unit 110.

The unbalanced mass may move freely inside the washing tub like laundry, or may be attached to an arbitrary surface of the washing tub with a magnet. In the case of the present invention, the microphone unit 120 and the wireless transmission unit 130 are mounted in a form in which damage is not caused by impact or rotation inside the lump.

Meanwhile, according to another embodiment, after attaching or mounting the operating sound measuring device 100 on the inside of the cover of the washing machine 1 or on the surface of the washing tub 2, the washing machine 1 is operated to operate the washing machine. It is also possible to measure the operating sound of (1). Since the body part 110 is fixed to the wall by centrifugal force like laundry when the washing tub rotates, a separate fixing device is not required, but when the operation sound measuring device 100 is attached, the body part 110 ) May include a coupling structure or material to be attached to the washing tub. In the case of specifying an attachment location for measurement accuracy and consistent measurement, a magnet may be attached to the body portion 110 to be attached to a specific portion of the washing tub.

For example, the surface of the body part 110 may be made of a material including an adhesive component such as an adsorption pad or a bond, so that the operation sound measuring device 100 can be detachably attached to the surface of the washing tub 2 . Compared to the case in which the operating sound measuring device 100 is used as the unbalanced mass, it is possible to further increase durability and measurement accuracy.

However, when the operating sound measuring device 100 is mounted on the surface of the washing tub 2 or the cover portion of the washing machine using a coupling structure such as a hook or latch structure, or Velcro, the hook or latch structure and the Velcro itself Not appropriate because of the sound.

The microphone unit 120 may be located inside the body unit 110 and may generate a measurement signal by measuring an internal operating sound when the washing machine 1 is operated. The microphone unit 120 may include one or a plurality of microphones, and each microphone may convert a sound pressure generated by an operating sound into a measurement signal, which is an electrical signal. The microphone unit 120 has a thin membrane to detect changes in sound pressure as vibrations of the membrane and convert them into electrical signals. The microphone unit 120 may store the generated measurement signal in an internal storage medium (not shown), or may transmit the generated measurement signal to the wireless transmission unit 130.

The wireless transmission unit 130 may be located inside the body unit 110, and may transmit a measurement signal received from the microphone unit 120 to the outside by using a wireless signal. Here, the wireless transmitter 130 utilizes various wireless communications including Wi-Fi, WiBro, WCDMA, Bluetooth, infrared communications, RFID, NFC, telemetry, mobile communication networks, etc. Can be sent out.

The signal analysis device 200 may receive a measurement signal from the operating sound measurement device 100, and may determine whether the washing machine 1 is abnormal by analyzing the received measurement signal. That is, the signal analysis device 200 may perform wireless communication with the operating sound measuring device 100, and the measurement signal received from the operating sound measuring device 100 is analyzed in a frequency domain or a time domain, and the It is possible to determine whether the washing machine 1 is abnormal or defective. Specifically, referring to FIG. 2(b), the signal analysis device 200 may include the wireless receiver 210 and the signal analysis unit 220.

The wireless receiver 210 may receive a measurement signal through communication with the wireless transmitter 130. The wireless receiver 210 may support a wireless communication method used by the wireless transmitter 130, and Wi-Fi, WiBro, WCDMA, Bluetooth, infrared communication, RFID, NFC, telemetry, and mobile communication networks It can support various wireless communication methods such as. Depending on the embodiment, instead of the wireless receiver 210 may further include a configuration such as USB that can extract the measurement signal from the storage medium.

The signal analysis unit 220 may receive a measurement signal from the wireless receiver 210, and analyze the operating sound inside the washing machine 1 by using the measurement signal. Specifically, the signal analysis unit 220 may determine whether the washing machine 1 is abnormal by comparing a waveform in the frequency domain i or the time domain ii of the measurement signal with a preset database.

(I) When determining whether the washing machine 1 is abnormal using a waveform in the frequency domain, the signal analysis unit 220 can compare the waveform in the frequency domain of the measurement signal with waveforms stored in the frequency waveform database. have. In this case, the frequency waveform database may store a waveform in a frequency domain of a standard signal measured by a washing machine in normal operation. Accordingly, the signal analysis unit 220 compares the frequency domain waveform of the received measurement signal with the frequency domain waveform of the standard signal, and then determines that the washing machine 1 has an abnormality if the waveform is different over a certain range. I can. Here, the standard signal may be derived by averaging signals measured by a washing machine in normal operation.

In addition, according to an embodiment, a frequency domain waveform of an abnormal signal measured by a washing machine operating abnormally may be stored in the frequency waveform database, and a characteristic difference when comparing the frequency domain waveform of the abnormal signal and the standard signal It can be extracted and stored. Accordingly, the signal analysis unit 220 may determine whether the washing machine 1 is abnormal by checking whether a characteristic shape of a frequency waveform appearing in the abnormal signal is included in the measurement signal.

Additionally, in the frequency waveform database, a shape of each characteristic frequency waveform may be stored according to the type of an abnormality or defect occurring in the washing machine, and the signal analysis unit 220 may store characteristic frequency waveforms included in the measurement signal. It is possible to determine the type of abnormality or defect occurring in the washing machine 1 according to the shape of.

More specifically, the analysis of the frequency domain is characterized by a cepstrum (cepstrum) operation. The cepstrum operation is an operation that receives time data of 0.4 seconds from the signal analysis unit 220 and converts it to a rotation frequency. The quefrency corresponding to the rotation frequency of the washing tub 1 and various motors ) To detect defects. The cepstrum operation may be performed as shown in FIG. 24.

In the cepstrum analysis, first, FFT transformation is performed using [Equation 1] in step 6-11 (S611).

Next, in step 6-12 (S612), the square of the absolute value is performed on the data of step 6-11 (S611). It can be implemented through [Equation 2].

Next, in step 6-13 (S613), a log10 value is calculated for the data of steps 6-12 (S612). It can be implemented through [Equation 3].

Next, in step 6-14 (S614), IFFT transform is performed on the data of step 6-13 (S613). It can be implemented through [Equation 4].

Next, in step 6-15 (S615), the square of the absolute value is performed on the data of step 6-14 (S614). It can be implemented through [Equation 5].

Next, in step 6-16 (S616), the largest value among the preset ranges of the data in steps 6-15 (S615) is calculated. That is, Fs in FIG. 24 refers to a sampling frequency, and when Fs is 20480 Hz, the largest value among 20480/11.5 (=1781)-th values from 20480/12.2 (=1678)-th values is calculated.

In the analysis of the frequency domain, the spectrum of the signal and the cepstrum can be compared as shown in [Table 1]. The left column of [Table 1] is the variables used in the spectrum representing the frequency characteristics, and the right column is the variables used in the cepstrum, and the counterparts to the spectrum.

In addition, FIG. 6 is an example obtained by cepstrum conversion performed to detect a defect linked to the motor rotation frequency among the defective patterns of the washing machine. The peak of the motor rotation frequency is found at 0.083 sec cuperancy, which is the reciprocal value of 12.05 Hz. According to the size of this peak, it is possible to determine whether it is defective.

spectrum Cepstrum Frequency Quefrency Harmonics Rahmonics Magnitude Gamnitude Phase Saphe Filter Lifter Low-pass filter Short-pass lifter High-pass filter Long-pass lifter

(Ii) The signal analysis unit 220 may determine whether or not the washing machine 1 is abnormal by using a waveform in the time domain of the measurement signal. Specifically, the signal analysis unit 220 may store a time waveform of a standard signal or a time waveform of an abnormal signal in the time waveform database, and then compare the time waveforms with the measurement signals. Here, when the time waveform of the measurement signal differs from the time waveform of the standard signal by a certain level or more, or the shape of the time waveform characteristic of the abnormal signal is included in the time waveform of the measurement signal, the washing machine (1) It can be determined that there is an abnormality in the

More specifically, the analysis of the time domain is characterized by an envelope operation. The envelope operation refers to regenerating an envelope through a low-pass filter by rectifying the received signal in a manner in which the signal analyzer 220 receives time data of 0.4 seconds and detects the envelope of the signal. The envelope operation may be performed as shown in FIG. 25.

In the envelope analysis, first, Hilbert transform is performed using [Equation 6] in step 6-21 (S621).

Next, in step 6-22 (S622), an absolute value is applied to the data of step 6-21 (S621). More specifically, step 6-22 (S622) takes an absolute value to the Hilbert transform result of [Equation 6], which is the same as [Equation 2] in the case of the cepstrum.

Next, in step 6-23 (S623), FFT transform is performed on the data of step 6-22 (S622). In step 6-23 (S623), FFT transform is performed on the data in step 6-22 (S622), which is the same as [Equation 1] in the case of the cepstrum.

Next, in step 6-24 (S624), a difference between a magnitude of 12.5 Hz and a magnitude value of 2.5 Hz is calculated from the data of the 6-23 step (S623). More specifically, since the envelope operation is an FFT using time data of 0.4 seconds in the signal analysis unit 220, since df = 2.5 Hz, the motor rotation frequency of 11.5 Hz to 12.1 Hz is expressed as 12.5 Hz. However, the motor rotation frequency is a variable that can vary depending on the characteristics of the washing machine product and the characteristics of the defect.

In the envelope operation, after applying a band pass filter, the envelope operation is FFT-converted to detect defects at frequencies corresponding to various motor rotation frequencies. Among the defective patterns, it may be difficult to detect by the cepstrum operation. If an impact occurs every time the motor rotates, the defect may be detected using the envelope operation.

Figure 7 is the first step for calculating the envelope, (a) is obtained by Fourier transform of the time signal x(t), and it is converted to a positive value while preserving the energy of the negative region (b). to be. Because the left and right sides are symmetric around the axis (b), the figure is doubled on the right side.

3 to 5 are schematic diagrams showing the operation of the defect inspection system according to an embodiment of the present invention. Hereinafter, a detailed operation of the defect inspection system according to an embodiment of the present invention will be described with reference to FIGS. 3 to 5.

First, as shown in Fig. 3, when the manufacturing of the washing machine 1 is completed, in order to check the operation state of the washing machine 1 in a first step (S10) and determine whether it is defective, the operating sound measuring device 100 may be put into the washing tub 2 of the washing machine 1.

The operating sound measuring apparatus 100 may include the microphone unit 120 and the wireless transmission unit 130 in a body having an unbalanced mass distribution. The operating sound measuring device 100 may have an unbalanced mass distribution in order to measure the operating sound more easily, and may be applied to the microphone unit 120 and the wireless transmission unit 130 when the washing machine 1 is operated. In order to protect from an impact, the body portion 100 may be formed of an elastic body such as rubber or plastic.

On the other hand, according to an embodiment, the operating sound measuring device 100 may be made of a material and a structure that can be detachable from the surface of the washing tub 2 inside the washing machine 1 or the cover of the washing machine 1, etc. In this case, the stability of the measuring device and the reliability of the signal can be improved.

Thereafter, as shown in FIG. 4, in the second step (S20 ), the washing machine 1 may be operated while the operating sound measuring device 100 is inserted into the washing tub 2. At this time, the operating sound measuring device 100 may measure the operating sound of the washing machine 1 in the washing tub 2 and generate a measurement signal. That is, since the operating sound measuring device 100 measures the operating sound in the washing tub 2, it is possible to minimize the effect of noise or noise generated outside the washing machine 1.

In addition, the operating sound measurement device 100 may transmit the generated measurement signal to the signal analysis device 200 located outside through wireless communication, and the signal analysis device 200 uses the received measurement signal. Thus, it is possible to determine whether the washing machine 1 is abnormal or defective.

When the operation sound measurement is completed, as shown in FIG. 5, the third step (S30) removes the operation sound measurement device 100 from the washing machine 1 to perform a defect inspection of the washing machine 1 I can finish it. That is, according to the defect inspection system according to an embodiment of the present invention, since a separate facility is not installed or an additional process is not required, cost reduction and productivity increase effects can be obtained together.

On the other hand, according to an embodiment, instead of transmitting the measurement signal using wireless communication, the operating sound measuring device 100 in FIG. 4 may be stored in a storage medium inside the operating sound measuring device 100. Thereafter, in FIG. 5, the operating sound measuring device 100 is removed from the washing machine 1, a measurement signal is extracted from the storage medium of the operating sound measuring device 100, and then input to the signal analysis device 200 It is also possible to determine whether the washing machine 1 is abnormal or defective.

Hereinafter, a noise defect detection system using a washing machine operation sound measuring apparatus according to the present invention will be described with reference to FIGS. 11 to 12 through an embodiment of extracting features for each noise defect.

First, in the first step (S100), as shown in FIG. 12, raw data collected by the microphone unit 120 is collected. The raw data is transmitted to the wireless receiver 210 through the wireless transmitter 130.

Next, in the second step (S200), the signal analysis device 200 receives the raw data through the wireless receiving unit 210, and the signal analysis unit 220 removes the background noise using a digital filter. do. As shown in Fig. 13, background noise was removed from the raw data, and a notch filter was used as the digital filter.

Next, in the third step (S300), the frequency domain or the time domain calculation order is selected using the signal analysis unit 220. More specifically, on the assumption that any defect exists in any case, the signal analysis unit 220 calculates both the frequency domain and the time domain through the following sequential steps, and detects the defect as a failure when it exceeds a predetermined criterion.

Next, in the fourth step (S400), when the signal analysis unit 220 selects a time domain in the third step, a filter area is selected. The filter is a bandpass filter, and the frequency domain of the filter inputs a value set first according to the characteristics of the product and the defect as described above.

In one embodiment, as shown in FIG. 12, the band pass filter selects any one or more of 2.5k to 4.0k Hz, 1.4k to 1.6k Hz, 3.4k to 3.9k Hz, and 4.0k to 7.0k Hz. I can.

15 is a graph showing the distribution of a bad signal in the 2.5k~4.0k Hz frequency domain, which is called a spectrogram showing time-frequency characteristics. Here, the time-frequency characteristics of the rotator are checked and defects occur. It is used to check the time and frequency band and to determine the bandpass filter range.

FIG. 19 is a graph showing a bad signal distributed in the 3.4k to 3.9k Hz region, and unlike a spectrogram, FIG. 19 is a spectrum showing a frequency characteristic over the entire time of rod data. It shows the case where the frequency range of the bandpass filter that can be detected by defective products can be selected.

Next, in a fifth step (S500), the raw data is divided by a predetermined length of time and overlapped. More specifically, the overlap is performed to find a time zone containing a defect in a long time signal from which a defective signal is measured, and in an embodiment, it can be calculated by dividing it by 0.4 second intervals, and in some cases, it can be adjusted to 0.5 seconds and 1 second. I can.

If the calculation is performed by dividing it by a predetermined length of time, an overlap is provided to effectively find the case of an intermittent bad signal, which can also be selected by the user in consideration of the characteristics of the signal. For example, if a time signal of 10 seconds is calculated as 0% overlap at 0.5 second intervals, the value of 20 is calculated, and if calculated as 50% overlap, it is calculated as a value of about 40 times.

Next, in the sixth step (S600), when the signal analysis unit 220 selects the frequency domain in the third step (S300), the analysis is performed through a cepstrum operation, and the time domain in the third step (S300) When is selected, the analysis is performed by selecting envelope operation or quartosis.

The quartosis is a method of making an abnormal sound that occurs temporarily appear more pronounced by the square root of the signal value. The quatosis is analyzed through the duration that the large value is maintained. The duration for which the value of the large quatosis is maintained means that vane's failure occurs in the previous time, so as shown in FIG. 26, the size of the quatosis values between the 1st to the 41st is 3.5 to 7.5. It is the number of times that the phosphorus value appears consecutively.

In the sixth step (S600), the cepstrum operation may be performed in steps 6-11 (S611) to 6-16 (S616) as shown in FIG. 24. Since the duration strum calculation is the same as described above, a simple description will be given of the duration strum calculation step below.

First, in steps 6-11 (S611), the time data generated in the fifth step (S500) is FFT transformed. Next, in step 6-12 (S612), the square of the absolute value is performed on the data of step 6-11 (S611). Next, in step 6-13 (S613), a log ₁₀ value is calculated for the data of step 6-12 (S612). Next, in steps 6-14 (S614), IFFT transform is performed on the data of steps 6-13 (S613). Next, in step 6-15 (S615), the square of the absolute value is performed on the data of step 6-14 (S614). Next, in step 6-16 (S616), the largest value among the preset ranges for the data in steps 6-15 (S615) is calculated.

In addition, in the sixth step (S600), the envelope operation may be performed in steps 6-21 (S621) to 6-24 (S624) as shown in FIG. 25. Since the envelope operation is the same as described above, the envelope operation step will be briefly described below.

First, in steps 6-21 (S621), Hilbert transform is performed on the overlapped time data generated in the fifth step (S500). Next, in step 6-22 (S622), an absolute value is applied to the data of step 6-21 (S621). Next, in step 6-23 (S623), FFT transform is performed on the data of step 6-22 (S622). Next, in step 6-24 (S624), a difference between a magnitude of 12.5 Hz and a magnitude value of 2.5 Hz is calculated from the data of the 6-23 step (S623).

Next, in the seventh step (S700), when the duration strum analysis or the envelope analysis is performed in the sixth step (S600), an average value is obtained, and when the kutosis analysis is performed in the sixth step (S700), the duration value is determined. Acquire.

The average value refers to an average value obtained after processing a negative number as 0 among values of indexes (the duration strum and envelope FFT) obtained by overlapping 70% of data of 0.4 seconds in the fifth step (S500).

Next, the eighth step (S800) is compared with a preset value from the average value or duration value obtained in the seventh step (S700).

Next, in the ninth step (S900), when the predetermined value is exceeded in the eighth step (S800), a defect for each type is determined.

As an example, as shown in FIG. 12, the preset value is determined as rotational failure when the average value exceeds 250 in the case of the duration strum analysis, and when the duration value exceeds 30, the drum It is determined as defective. In addition, in the case of the envelope analysis, when the band pass filter is 1.4k to 1.6k Hz and the average value exceeds 4X10 ^-5 , the motor is defective, and when the band pass filter is 3.4k to 3.9k Hz, the average value is If it exceeds 5X10 ^-5 , the rotation axis is defective, and if the average value in the envelope analysis exceeds 5X10 ^-5 when the band pass filter is 4.0k to 7.0k Hz, the tape is defective, and the average value in the duration strum analysis If this exceeds 5X10 ^-5 , it can be judged as a cable contact failure. However, the preset average value and duration value may vary depending on the type of washing machine 1.

The present invention is not limited by the above-described embodiments and the accompanying drawings. It will be apparent to those of ordinary skill in the art to which the present invention pertains, that components according to the present invention can be substituted, modified, and changed within the scope of the technical spirit of the present invention.

The operating sound measuring apparatus and the defect inspection system including the same according to an embodiment of the present invention measure the operating sound inside the washing machine, thus minimizing the effect of external noise, etc. to clearly measure the operating sound and abnormal sound caused by the fault. can do. In addition, since separate facilities or additional processes such as a soundproof tunnel, a noise separation device, and a directional microphone are not required, cost reduction and production increase effects can be obtained.

In the working sound measuring device and the defect inspection system including the same according to an embodiment of the present invention, since the working sound measuring device located inside the washing machine transmits the measurement signal to the signal processing device located outside by using a wireless signal, It is easy and fast to collect measurement signals, and it is possible to quickly determine whether the washing machine to be inspected is defective.

As described above, it will be understood that the technical configuration of the present invention described above can be implemented in other specific forms without changing the technical spirit or essential features of the present invention by those skilled in the art.

Therefore, the embodiments described above are to be understood as illustrative and non-limiting in all respects, and the scope of the present invention is indicated by the claims to be described later rather than the detailed description, and the meaning and scope of the claims and the All changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

1. Washing machine
2. Washing tub
100. Operating sound measuring device
110. Body
120. Microphone part
130. Wireless Transmitter
200. Signal analysis device
210. Wireless receiver
220. Signal Analysis Unit
S10. The first step of introducing the operating sound measuring device 100 into the washing tub 2 of the washing machine 1 in order to check the operating state of the washing machine 1 and determine whether it is defective.
S20. The second step of operating the washing machine 1 while the operating sound measuring device 100 is inserted into the washing tub 2
S30. The third step of removing the operating sound measuring device 100 from the washing machine 1
S100. The first step of collecting raw data by operating the washing machine
S200. The second step to removing background noise
S300. The third step of selecting the frequency domain or the time domain calculation order
S400. When the time domain is selected in the third step (S300), a fourth step of selecting a filter area
S500. The fifth step of overlapping 70% of the 0.4 second long data
S600. When the frequency domain is selected in the third step (S300), cepstrum analysis is performed, and when the time domain is selected in the third step (S300), the analysis is performed by selecting envelope analysis or quartosis analysis.
S700. A seventh step of acquiring an average value when a cepstrum analysis or an envelope analysis is performed in the sixth step (S600), and a duration value when a quartosis analysis is performed in the sixth step (S600)
S800. The eighth step of comparing the average value or duration value obtained in the seventh step (S700) with a preset value
S900. The ninth step of determining a defect for each type when the predetermined value is exceeded in the eighth step (S800)
S611. Step 6-11 of generating 0.4 second long data in cepstrum operation
S612. Steps 6-12 of performing FFT transformation in step 6-11 (S611)
S613. Steps 6 to 13 of the square of the absolute value in step 6-12 (S612)
S614. Steps 6-14 of calculating the log10 value in step 6-13 (S613)
S615. Steps 6-15 of performing IFFT transformation in step 6-14 (S614)
S616. Steps 6-16 of squaring the absolute value in step 6-15 (S615)
S617. Steps 6-17 of calculating the largest value among the preset ranges in step 6-16 (S616)
S621. Step 6-21 of generating 0.4-second length data in envelope operation
S622. Step 6-22 of performing Hilbert transformation in step 6-21 (S621)
S623. Step 6-23 of performing an absolute value in step 6-22 (S622)
S624. Step 6-24 of performing FFT transformation in step 6-23 (S623)
S625. Steps 6-25 of calculating a difference between a magnitude of 12.5 Hz and a magnitude of 2.5 Hz in the 6-24 (S624)

Claims (10)

A working sound measuring device 100 that is put into the washing tub 2 of the washing machine 1 and measures the working sound of the washing machine 1; And
A signal analysis device 200 for determining whether the washing machine 1 is abnormal by analyzing the operating sound measured by the operating sound measuring device 100; and
The operating sound measuring device 100,
A microphone unit 120 for generating a measurement signal by measuring an internal operating sound when the washing machine 1 is operated;
A wireless transmission unit 130 for transmitting the measurement signal received from the microphone unit 120 to the outside by using a wireless signal; And
The microphone unit 120 and the wireless transmission unit 130 when combined, the body portion 110 for absorbing and protecting the shock applied from the outside; consisting of,
A washing machine noise defect detection system, characterized in that by combining the microphone unit 120 and the wireless transmission unit 130 to form an unbalanced mass when the washing tub rotates.
The method of claim 1,
The signal analysis device 200,
A wireless receiver 210 for receiving the measurement signal from the wireless transmitter; And
A washing machine noise defect detection system comprising: a signal analysis unit 220 that receives the measurement signal from the wireless reception unit 210 and analyzes the operating sound inside the washing machine 1.
The method of claim 1,
The signal analysis unit 220,
A washing machine noise defect detection system, characterized in that it determines whether or not the washing machine (1) is abnormal by comparing a waveform of a measurement signal in a frequency domain or a time domain with a preset database.
The method of claim 3,
The frequency domain,
A washing machine noise defect detection system, characterized in that analyzing through a cepstrum operation.
The method of claim 3,
The time domain,
A washing machine noise defect detection system, characterized in that it analyzes through an envelope calculation.
A first step of operating the washing machine 1 to collect raw data using the operating sound measuring device 100 and then transmitting the raw data;
A second step of removing background noise by receiving the raw data using the signal analysis device 200;
A third step of selecting a frequency domain or a time domain calculation order using the signal analysis unit 220 for analyzing a signal in the signal analysis device 200;
A fourth step of selecting a filter region when the signal analysis unit 220 selects a time region in the third step;
A fifth step of dividing and overlapping the raw data by a predetermined length of time;
The signal analysis unit 220 analyzes through a cepstrum operation when the frequency domain is selected in the third step, and analyzes by selecting an envelope calculation or a quartosis when the time domain is selected in the third step. ;
A seventh step of acquiring an average value when a cepstrum analysis or an envelope analysis is performed in the sixth step, and a duration value when a kutosis analysis is performed in the sixth step;
An eighth step of comparing the average value or duration value obtained in the seventh step (S700) with a preset value; And
A noise defect detection method using a washing machine noise defect detection system, characterized in that performed by the ninth step of determining a defect for each type when the predetermined value is exceeded in the eighth step.
The method of claim 6,
In the sixth step, the cepstrum operation,
Steps 6-11 of FFT transforming the time data generated in the fifth step;
Steps 6-12 of squared absolute values on the data of steps 6-11;
Steps 6-13 of calculating log ₁₀ values for the data of steps 6-12;
Steps 6-14 of performing IFFT transformation on the data in steps 6-13;
Steps 6-15 of squared absolute values on the data of steps 6-14;
A method for detecting noise defects using a washing machine noise defect detection system, characterized in that performed through steps 6-16 of calculating the largest value among a preset range in the data of the steps 6-15.
The method of claim 7,
In step 6-11,
FFT conversion of time data is a noise defect detection method using a washing machine noise defect detection system, characterized in that [Equation 1]:
[Equation 1]

.
The method of claim 6,
In the sixth step, the envelope operation,
Step 6-21 of performing Hilbert transform on the overlapped time data generated in the fifth step;
Steps 6-22 of performing absolute values on the data of steps 6-21;
Steps 6-23 of performing FFT transformation on the data of steps 6-22;
A method for detecting noise defects using a washing machine noise defect detection system, characterized in that it is carried out through steps 6 to 24 of calculating a difference between a magnitude of 12.5 Hz and a magnitude of 2.5 Hz in the data of the 6-23 steps.
The method of claim 9,
In the step 6-21,
Hilbert conversion of time data is a noise defect detection method using a washing machine noise defect detection system, characterized in that [Equation 6]:
[Equation 6]

.

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