JP2018084557A - Waveform recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable performing similarity determination of a waveform by matching levels of both measurement waveforms, when the measurement waveform are compared with each other by means of a histogram.SOLUTION: A waveform recording apparatus comprises: an input unit 2 that performs A/D conversion of an analogue measured signal to catch as measurement data; a storage unit 5; a display unit 6 that displays a measurement waveform; a control unit 4 that processes the measurement data in a predetermined way; and an operation unit 3. The control unit 4 creates a histogram from the measurement data, in which the A/D conversion of them is performed, for each measurement waveform input from the input unit 2 to store in the storage unit 5, when a basic waveform being reference is selected from among measurement waveforms stored in the storage unit 5 during searching the waveform by the operation unit 3, obtains similarity by comparing the histogram of the basic waveform with the histogram of other measurement waveform, performs predetermined waveform search on the basis of the similarity, and when the result is displayed on the display unit 6, adds an off-set value (±α) set by the operation unit 3 to either of the measurement data of the basic waveform or the measurement data of the other measurement waveform.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a waveform recording apparatus, and more particularly to a waveform recording apparatus having a waveform search function based on histogram comparison of measured waveform data.

  The waveform recording device includes an input unit, a storage unit, a display unit, a control unit, and an operation unit as its basic configuration, and digitally converts an analog signal measured from an object to be measured from the input unit by A / D conversion. For each measurement item set in the operation unit, the control unit performs a predetermined process on the measurement item, and displays the waveform data on the display unit sequentially, for each predetermined time axis length. One waveform file (one waveform data group) is stored in the storage unit.

  According to this, it is possible to specify a waveform file name or number, read out desired waveform data from the storage unit, and display it on the display unit. However, when the number of waveform files stored in the storage unit increases, it is not easy to read a desired waveform (similar waveform, dissimilar waveform, abnormal waveform, etc.) from among them.

  Therefore, in the invention described in Patent Document 1, search zones (abnormal areas) are set in the time direction (horizontal axis direction) and the measurement value direction (vertical axis direction), and whether there is data in this search zone. For example, an abnormal waveform is searched.

  However, in order to perform such a search, not only is it time-consuming to set a search zone in advance, but if the waveform stored in the waveform file is not recognized to some extent, a search zone with high search accuracy can be obtained. There is a problem that it cannot be set.

  In the invention described in Patent Document 2, an average value X and standard deviation σ of waveform data belonging to the same position (sampling position) of a plurality of waveform files are obtained, and X ± K · σ is obtained for each position. A voltage range (K is an arbitrary coefficient set by the user) is set, and homogeneous or heterogeneous waveform data is extracted (searched) depending on the presence or absence of waveform data within this voltage range.

  However, even in the invention described in Patent Document 2, the position of each waveform file is sequentially shifted, the average value X and the standard deviation σ are calculated at each position, and a voltage range of X ± K · σ is set. Therefore, there is a problem that the calculation is burdened.

  Therefore, the present applicant has made it possible to search for an abnormal portion of a waveform by comparing measured waveforms without setting a search condition including a search zone and a search formula in advance as Patent Document 3. A waveform recording device is proposed.

  That is, according to the invention described in Patent Document 3, a measurement waveform is divided into a plurality of waveform data groups in a time-sequential order at a constant designated period, and measurement data (A / D conversion value) is obtained for each waveform data group. ) Is created and stored in the storage unit. When a waveform data group of a basic waveform (original waveform) serving as a reference is selected from the operation unit during waveform search, a histogram based on the A / D conversion value of the basic waveform is selected. And a histogram based on A / D conversion values of other waveform data groups to obtain a similarity (score), so that the similarity can be obtained without setting a search zone or a search expression in advance. Based on the above, it is possible to quickly find an abnormal waveform, a portion with a large waveform change, and the like.

JP 2000-292449 A JP 2007-0573303 A Japanese Patent Laid-Open No. 2006-080830

  However, if the waveform looks similar but the levels are different, especially in the case of direct currents with different levels, the similarity (score) will be lower, and the similarity will be worse than other dissimilar waveforms. Reliability can be compromised.

  Accordingly, it is an object of the present invention to provide a waveform recording apparatus that can determine the similarity of waveforms by matching the levels of both measured waveforms when comparing measured waveforms with a histogram.

In order to solve the above-mentioned problems, the present invention provides an input unit for A / D-converting an analog signal to be measured measured from an object to be measured and taking it as digital measurement data, and a storage unit for storing the measurement data. A display unit for displaying a measurement waveform based on the measurement data on a screen, a control unit for processing the measurement data in a predetermined manner, and controlling writing and reading of the measurement data to and from the storage unit, and the control unit And a waveform recording apparatus comprising an operation unit for giving a predetermined instruction including a waveform search instruction,
For each measurement waveform input from the input unit, the control unit creates a histogram from the A / D converted measurement data and stores the histogram in the storage unit. When a basic waveform as a reference is selected from the measurement waveforms stored in the storage unit, a similarity is obtained by comparing the histogram of the basic waveform with the histograms of other measurement waveforms. When a predetermined waveform search is performed based on the result and the result is displayed on the display unit, the offset value (±) set by the operation unit to either the measurement data of the basic waveform or the measurement data of the other measurement waveform is displayed. It is characterized by adding α).

  According to a preferred aspect of the present invention, when the value of the similarity based on the comparison between the basic waveform and the other measurement waveform is substantially “0”, the control unit The similarity is calculated again by adding the offset value (± α) to any of the measurement data of the other measurement waveforms.

  The basic waveform is a direct current waveform, and the offset value (± α) is preferably added to the measurement data.

を正規化することにより求められる。 In the present invention, the similarity is based on the histogram intersection method, and H ₁ is a histogram value based on measurement data of a basic waveform, H ₂ is a histogram value based on measurement data of another measurement waveform, and i is a variable of the number of gradations. The following formula (1)

Is obtained by normalizing.

  According to the present invention, the histogram of the basic waveform and the histogram of another measurement waveform are compared to determine the similarity, and a predetermined waveform search based on the similarity is performed, preferably a waveform search by the histogram crossing method is performed. When the result is displayed on the display unit, the offset value (± α) set by the operation unit is added to either the measurement data of the basic waveform or the measurement data of another measurement waveform. Waveforms that are different but visually similar can be determined as high similarity. Therefore, a search result close to that of the human eye can be obtained, and the reliability of the device can be improved.

1 is a block diagram schematically showing the configuration of a waveform recording apparatus according to an embodiment of the present invention. (A) A waveform diagram showing a part of a measured waveform, (b) a graph showing a histogram based on the A / D conversion value. (A) A waveform diagram showing a first basic waveform (direct current) in the present embodiment, (b) a table showing voltage levels of second and third basic waveforms to which the first basic waveform and offset are added. (A) A waveform diagram showing first to third measurement waveforms compared with the basic waveform, and (b) a table representing each voltage level of each measurement waveform. (A) a graph showing a histogram of the first basic waveform; (b) a graph showing a histogram of the second basic waveform; (c) a graph showing a histogram of the third basic waveform; A table showing the frequency numbers. (A) a graph showing the histogram of the first measurement waveform; (b) a graph showing the histogram of the second measurement waveform; (c) a graph showing the histogram of the third measurement waveform; A table showing the frequency numbers.

  Next, embodiments of the present invention will be described with reference to FIGS. 1 to 6, but the present invention is not limited thereto.

  As shown in FIG. 1, the waveform recording apparatus 1 according to the present embodiment includes an input unit 2, an operation unit 3, a control unit 4, a storage unit 5, and a display unit 6 as a basic configuration. ing.

  The input unit 2 includes an A / D converter, converts a signal to be measured (analog electrical signal) from a measurement target (not shown) into digital measurement data (waveform data), and sends it to the control unit 4 at the subsequent stage. Send it out.

  In this embodiment, the input unit 2 has a plurality of input channels CH1 to CHn, sequentially selects signals under measurement input from these input channels by a multiplexer (not shown), and passes through the A / D converter. However, the input channel may be a single channel input unit.

  A CPU (Central Processing Unit) or a microcomputer may be used for the control unit 4. The control unit 4 stores measurement data from the input unit 2 in the storage unit 5, and measures from the storage unit 5. Data is read out and sent to the display unit 6.

  In the present embodiment, the control unit 4 performs predetermined processing on the measurement data based on an instruction from the operation unit 3 to obtain the impedance, power, effective value, and the like as well as the calculation function and the determination function. A compression function, a trigger function, etc. are provided.

  The storage unit 5 includes a ROM (Read Only Memory) 5a that stores an operation program of the control unit 4, a storage memory 5b that sequentially stores measurement data, an HDD, a USB memory, and the like connected via a predetermined interface. An external memory 5c such as an SD card is provided, and measurement data in the storage memory 5b is stored in the external memory 5c according to an instruction from the operation unit 3.

  The operation unit 3 includes a keyboard, a touch panel, or the like. The operation unit 3 gives the control unit 4 instructions for waveform search to be described later in addition to instructions for various calculation items and settings for trigger conditions.

  The display unit 6 includes a screen made up of a liquid crystal display panel or the like. The screen may be either a monochrome display or a color display, but if it is a color display, the measurement waveform of each input channel can be displayed in different colors.

  In the present invention, the waveform recording apparatus 1 has a waveform search function. Therefore, the control unit 4 first creates a histogram (frequency distribution diagram) based on the A / D conversion values of the measurement data.

  The case where a sine wave measurement waveform W1 is displayed on the screen of the display unit 6 as shown in FIG. 2A will be described as an example. When the histogram is created, the operation unit 3 performs measurement waveform W1. As a range in which the histogram is created, one cycle or a cycle that is an integer multiple thereof is designated.

  When the analog signal under measurement is converted into 16-bit measurement data by the A / D converter of the input unit 2, the A / D conversion value of one point of the measurement data is one of 0 to 65535. Take the value.

  Since the range (number of gradations) of the measurement data is too wide as it is, the control unit 4 divides the 16-bit measurement data by 256, and as shown in FIG. A histogram is created in which the horizontal axis is 256 gradations and the vertical axis is the number of data of A / D conversion values (frequency number).

  If the measurement data is 8 bits, a histogram is created with the raw data without performing the above division, but the number of gradations on the horizontal axis may be arbitrarily selected. For example, when the number of gradations is 128, if the measurement data is 16 bits, it is divided by 512, and if it is 8 bits, it is divided by 2.

  In this way, the control unit 4 creates a histogram for each measurement waveform (a waveform based on measurement data obtained by A / D converting an analog signal to be measured), and stores the histogram in the storage memory 5b of the storage unit 5 and / or the external memory. Store in 5c.

  At the time of waveform search, when a measurement waveform that is an original waveform serving as a search reference is designated by the operation unit 3, the control unit 4 includes a histogram of the original waveform designated as the search reference and another measurement waveform (“ The histogram of “searched waveform” may be read out), and the similarity is calculated by the following equation (1A).

In the present embodiment, the histogram crossing method is applied. In the above formula (1), H ₁ is the histogram value of the original waveform, H ₂ is the histogram value of the waveform to be searched, i is the variable of the number of gradations, In this example, i = 1 to 256 (0 to 255). min (H ₁ , H ₂ ) means an arithmetic expression for obtaining a smaller value by comparing the respective classes, and the histogram value is the number of data in one gradation.

  The similarity obtained from the above equation (1A) is normalized by the following equation (2) to obtain a numerical value of 1.000 or less. The closer the value is to “1”, the higher the similarity is. It can be determined that the waveform is similar to the original waveform, and the waveform is similar to the original waveform with a lower degree of similarity as it approaches “0” (an abnormal waveform, a waveform with a high rate of change).

  For the histogram intersection method, see, for example, “MJ Swain and DH Ballard: Color Indexing, International Journal of Computer Vision. Vol. 7. no. 1. pp.11-32. 1991.”, “Okamoto Kazushi et al. (Proposal of histogram intersection method based on t-norm and its application to image retrieval): See Japan Society for Kansei Engineering, Vol.10 No.1 pp. 11-21 (2010).

  Next, the direct current of 35 V shown in FIG. 3A is used as a basic waveform (first basic waveform), and the first to third measured waveforms 1 to 3 shown in FIG. A waveform search example based on the similarity by the histogram crossing method will be described.

  In this example, in addition to the first basic waveform of DC 35V shown in FIG. 3A, the basic waveform includes a first basic waveform of 40V DC as shown in the table of FIG. 3B. A second basic waveform of DC 75V obtained by adding an offset voltage and a third basic waveform of 95V DC obtained by adding an offset voltage of 60V DC to the first basic waveform are prepared.

  Note that the basic waveform is specified by the operation unit 3, but in the actual machine, the control unit 4 performs, for example, ± 20V, ± 40V,. Many basic waveforms are created by adding the offset voltage.

  In contrast, the first measurement waveform 1 compared with the basic waveform is a sine wave having an amplitude of 0 to 100 V and a period of 1 mS, the second measurement waveform 2 is a DC waveform of 76 V, and the third measurement waveform 3 is experimental. As shown in the table of FIG. 4B, the voltage gradually increases from 0 to 0.25 mS and reaches a peak of 98.125 V at 0.25 mS. Is a mountain-shaped waveform that gradually decreases to 70 V at 1 mS.

  In both the basic waveform (first to third basic waveforms) and the measured waveforms 1 to 3, for convenience of explanation, the number of data sampling at the time axis length of 1 mS is simply set to 20, but the number of data sampling is arbitrarily determined by the operation unit 3. In practice, a larger number of samplings is set. 3 and 4, there are 21 sampled data, but in this example, data on time axis 0 is not adopted.

  The control unit 4 creates histograms for the basic waveforms (first to third basic waveforms) and the measured waveforms 1 to 3 based on the measurement data shown in the tables of FIGS. 3B and 4B. .

  In this example, a histogram is created with a scale interval 20V on the vertical axis (level axis) of the graphs of FIGS. 3A and 4A as one data section (one gradation), and 20 samples of measurement data are created. The frequency depends on which data section is assigned. The scale interval for creating this histogram may be arbitrarily set, for example, 5V interval, 10V interval, etc.

  Each measurement data of the first to third basic waveforms is distributed as shown in FIG. As a result, the histogram shown in FIG. 5A is created for the first basic waveform (DC 35V), and the histogram shown in FIG. 5B is created for the second basic waveform (DC 75V). For the three basic waveforms (DC 95V), a histogram shown in FIG. 5C is created.

  Moreover, each measurement data of the measurement waveforms 1 to 3 is distributed as shown in FIG. Therefore, the histogram shown in FIG. 6A is created for the measurement waveform 1, the histogram shown in FIG. 6B is created for the measurement waveform 2, and the histogram shown in FIG. 6C is created for the measurement waveform 3. A histogram is created.

  Next, the control unit 4 calculates the degree of similarity (score) of how similar the measured waveforms are based on the basic waveform.

  First, the first basic waveform to which no offset is applied in FIG. 5A, the measurement waveform 1 in FIG. 6A, the measurement waveform 2 in FIG. 6B, and the measurement waveform 3 in FIG. 6C. Calculate each score. The number of measurement data (frequency number) to be calculated is the number of measurement data included in the 40 V data section of each histogram.

  The number of measurement data included in the 40V data section of the first basic waveform is 20, whereas the number of measurement data included in the same data section of the measurement waveform 1 is 4, so the score is 0.2. (= 4/20), the number of measurement data included in the same data section of the measurement waveform 2 is 0, so the score is 0 (= 0/20), and the measurement included in the same data section of the measurement waveform 3 Since the number of data is 1, the score is 0.05 (= 1/20).

If you arrange them from the left in order from the lowest score
Measurement waveform 2 “0”, measurement waveform 3 “0.05”, measurement waveform 1 “0.2”
It becomes the order of. In the observation by appearance, since the measurement waveform 2 is a direct current, it is more similar to the first basic waveform than the other measurement waveforms 1 and 3, but it is determined that the dissimilarity is not the most similar in contrast with the histogram. .

  Therefore, the control unit 4 calculates the scores of the second basic waveform (DC 75V) to which the offset voltage is added next and the measured waveforms 1, 2, and 3, and the third basic waveform (DC 95V). Then, each score of the measured waveforms 1, 2, 3 is calculated.

  For comparison with the second basic waveform, the number of measurement data included in the 80V data section is targeted. The number of measurement data included in the same data section of the second basic waveform is 20, whereas the number of measurement data included in the same data section of the measurement waveform 1 is 4, so the score is 0.2. (= 4/20), the number of measurement data included in the same data section of the measurement waveform 2 is 20, so the score is 1 (= 20/20), and the measurement included in the same data section of the measurement waveform 3 Since the number of data is 7, the score is 0.35 (= 7/20).

  For comparison with the third basic waveform, the number of measurement data included in the 100 V data section is targeted. The number of measurement data included in the same data section of the third basic waveform is 20, whereas the number of measurement data included in the same data section of the measurement waveform 1 is 5, so the score is 0.25. (= 5/20), since the number of measurement data included in the same data section of the measurement waveform 2 is 0, the score is 0 (= 0/20), and the measurement included in the same data section of the measurement waveform 3 Since the number of data is 11, the score is 0.55 (= 7/20).

When the scores of the measurement waveforms 1 to 3 with respect to the second basic waveform and the third basic waveform are arranged from the left in ascending order (the order in which the waveforms are not similar),
Measurement waveform 1 “0.25”, measurement waveform 3 “0.55”, measurement waveform 2 “1”
It is determined that the measured waveform 2 has the highest score and is similar to the basic waveform.

  As described above, according to the histogram intersection method, the basic waveform and the measured waveform are similar to each other, but if both waveforms have a level difference, it is determined that they are different, but by applying an offset, Waveforms that are different in level but are visually similar can be determined as having high similarity. Therefore, a search result close to that of the human eye can be obtained, and the reliability of the device can be improved.

  In the above embodiment, a DC waveform is selected as the basic waveform, but an AC waveform or a pulsating waveform may be selected as the basic waveform. Further, the offset may be applied to the measured waveform on the searched waveform side instead of the basic waveform. That is, the level of the measurement waveform may be shifted by ± α of the offset value, and such an aspect is also included in the present invention.

DESCRIPTION OF SYMBOLS 1 Waveform recording device 2 Input part 3 Operation part 4 Control part 5 Memory | storage part 6 Display part

Claims (4)

An analog input signal measured from an object to be measured is A / D converted and captured as digital measurement data, a storage unit for storing the measurement data, and a measurement waveform based on the measurement data on the screen A display unit for displaying, processing the measurement data in a predetermined manner, a control unit for controlling writing and reading of the measurement data to and from the storage unit, and giving a predetermined instruction including a waveform search instruction to the control unit In a waveform recording apparatus comprising an operation unit,
For each measurement waveform input from the input unit, the control unit creates a histogram from the A / D converted measurement data and stores it in the storage unit,
When the reference waveform is selected from the measurement waveforms stored in the storage unit by the operation unit during the waveform search, the histogram of the basic waveform is compared with the histograms of other measurement waveforms. To obtain a similarity, perform a predetermined waveform search based on the similarity, and display the result on the display unit,
A waveform recording apparatus, wherein an offset value (± α) set by the operation unit is added to either the measurement data of the basic waveform or the measurement data of the other measurement waveform.   When the similarity value obtained by comparing the basic waveform with the other measurement waveform is substantially “0”, the control unit measures the basic waveform measurement data or the other measurement waveform measurement data. The waveform recording apparatus according to claim 1, wherein the similarity is calculated again by adding the offset value (± α) to any one of the above.   The waveform recording apparatus according to claim 1, wherein the basic waveform is a direct current waveform, and the offset value (± α) is added to the measurement data. The similarity is based on the histogram intersection method, and H ₁ is a histogram value based on measurement data of a basic waveform, H ₂ is a histogram value based on measurement data of another measurement waveform, and i is a variable of the number of gradations (1) )

The waveform recording apparatus according to claim 1, wherein the waveform recording apparatus is obtained by normalizing.

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