Detection device, time synchronization method, time synchronization program, and detection system

Abstract

To perform time synchronization considering a positional relationship among multiple sensors.SOLUTION: A detection device 10 includes: an internal clock; an oscillation section 11 for generating vibration each time when a condition regarding time is satisfied; a vibration reception section 12 for detecting vibration; a measurement section 142 for measuring time until the vibration reception section 12 detects vibration after the oscillation section 11 generates vibration; a determination section 141 for determining a mode according to whether time measured by the measurement section 142 is longer than a prescribed interval time; and a correction section 143 for determining whether deviation of the internal clock is corrected on the basis of reference time when determining a specific mode and, if it is determined that the deviation is corrected, correcting the internal clock.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a detection device, a time synchronization method, a time synchronization program, and a detection system.

Background Art

[0002] A method is known for identifying the position of the source of vibration by comparing sensor values related to vibrations measured by a plurality of sensors based on the measured time. Note that vibration includes sound.

[0003] Also, Patent Document 1 describes a method for synchronizing the times of internal clocks of two sensors by having the two sensors output vibrations to each other and each measuring the vibration output by the other.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the conventional technology has a problem in that it may not be possible to perform time synchronization considering the positional relationship between a plurality of sensors.

[0006] For example, the arrangement of a plurality of sensors may differ depending on whether they are before or after installation. In this case, it is conceivable that the positional relationship between the sensors is different depending on whether it is before or after installation. On the other hand, in the conventional technology, the positional relationship between the sensors due to whether it is before or after installation is not considered.

[0007] For example, even if a time difference between sensors is detected by the method described in Patent Document 1, it is difficult to determine whether the difference is due to a deviation of the internal clock itself or due to a change in propagation time caused by a change in the positional relationship.

[0008] When the internal clock is deviated, correction of the internal clock is necessary for time synchronization. On the other hand, when a time difference is detected due to a change in the positional relationship between sensors, correction of the internal clock is unnecessary.

[0009] In one aspect, it is an object to perform time synchronization in consideration of the positional relationship between a plurality of sensors.

Means for Solving the Problems

[0010] A detection device according to one aspect includes an internal clock, an oscillation unit that generates oscillations each time a time-related condition is satisfied, a vibration receiving unit that detects the oscillations, a measurement unit that measures the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the oscillations, a determination unit that determines a mode based on whether the time measured by the measurement unit is longer than a prescribed interval time, and when it is determined that it is a specific mode, a correction unit that determines whether to correct the deviation of the internal clock based on a reference time and corrects the internal clock when it is determined to correct.

[0011] A time synchronization method according to one aspect is a time synchronization method executed by a detection device including an internal clock, an oscillation unit that generates oscillations each time a time-related condition is satisfied, and a vibration receiving unit that detects the oscillations, and includes a measurement step of measuring the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the oscillations, a determination step of determining a mode based on whether the time measured by the measurement step is longer than a prescribed interval time, and when it is determined that it is a specific mode, a correction step of determining whether to correct the deviation of the internal clock based on a reference time and correcting the internal clock when it is determined to correct.

[0012] The time synchronization program related to one aspect causes a detection device including an internal clock, an oscillation unit that generates oscillations every time a condition related to time is satisfied, and a vibration receiving unit that detects the oscillations, to perform a measurement step of measuring the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the oscillations, a determination step of determining a mode based on whether the time measured in the measurement step is longer than a specified interval time, and when it is determined that it is a specific mode, a correction step of determining whether to correct the deviation of the internal clock based on a reference time and, when it is determined to correct, correcting the internal clock.

[0013] A detection system related to one aspect is a detection system having a first detection device including a first internal clock and a second detection device including a second internal clock, wherein the first detection device includes a first oscillation unit that generates oscillations every time a condition related to time is satisfied, a first vibration receiving unit that detects the oscillations generated by the second detection device, a measurement unit that measures the time from when the first oscillation unit generates oscillations until the first vibration receiving unit detects the oscillations, a determination unit that determines a mode based on whether the time measured by the measurement unit is longer than a specified interval time, and when it is determined that it is a specific mode, a correction unit that determines whether to correct the deviation between the first internal clock and the second internal clock based on a reference time and, when it is determined to correct, corrects the first internal clock or the second internal clock, and the second detection device has a second oscillation unit that generates oscillations every time a condition related to time is satisfied.

Advantages of the Invention

[0014] According to one embodiment, time synchronization can be performed considering the positional relationship between a plurality of sensors.

Brief Description of the Drawings

[0015]

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[0016] Hereinafter, embodiments of the detection device, time synchronization method, time synchronization program, and detection system disclosed in the present application will be described in detail with reference to the drawings. Note that the invention of the present application is not limited by the embodiments described here. Also, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate. Further, the embodiments can be appropriately combined within a non - contradictory range.

[0017] [First Embodiment] Using FIG. 1, the configuration of the detection system according to the first embodiment will be described. It is a diagram showing a configuration example of the detection system according to the first embodiment.

[0018] As shown in FIG. 1, the detection system 1 includes detection devices 10a, 10b, 10c, and 10d. In the following description, the detection devices may be referred to as detection device 10 without distinguishing each detection device.

[0019] The detection system 1 is a system for detecting abnormalities in equipment. The equipment is, for example, a motor and a pump provided in a plant. The equipment always generates vibrations during operation. For example, when the equipment is physically damaged, it is conceivable that the waveform (frequency, etc.) of the vibration generated from the equipment changes.

[0020] The detection device 10 is a sensor that detects vibrations with a changed waveform as abnormal vibrations. The detection system 1 can identify the source of the abnormal vibration based on the time when each of the detection devices 10 detects the abnormal vibration, and the vibration propagation status, magnitude (including sound pressure), etc. For example, the detection system 1 identifies that there is a source of abnormal vibration at position 200 in FIG. 1.

[0021] At this time, if the internal clock of the detection device 10 is offset, the time when the abnormal vibration is detected becomes inaccurate. As a result, the detection system 1 cannot accurately identify the source of the abnormal vibration. Note that the offset of the internal clock includes not only the absolute offset from the accurate time but also the relative offset between devices. In order for the detection system 1 to identify the source of the abnormal vibration, it is sufficient that there is no relative offset of the internal clocks between the detection devices 10.

[0022] Also, the detection system 1 only needs to include a plurality of detection devices 10. The number of detection devices 10 included in the detection system 1 is not limited to that shown in FIG. 1.

[0023] The detection device 10 generates vibrations. Further, the detection device 10 detects vibrations. Note that the vibrations include sound. Also, the transmission medium of the vibrations may be any of a gas, a liquid, and a solid. The installation location of the detection device 10 may be in the air or in water.

[0024] Based on the result of comparing the time when the vibration was generated and the time when the vibration was detected, the detection device 10 determines whether the internal clock is offset, and appropriately corrects the internal clock according to the determination result.

[0025] Note that the detection device 10 can also use the mechanism for detecting vibrations to detect device abnormalities for time synchronization. On the other hand, the detection device 10 may be a sensor that detects device abnormalities from other information such as images or pressure without relying on vibrations. In that case, the detection device 10 is provided with a separate mechanism for detecting vibrations for the purpose of time synchronization.

[0026] Note that the determination of the offset of the internal clock can also be realized by using GPS (Global Positioning System) or the Internet. On the other hand, GPS and the Internet cannot be used in an environment where radio waves are blocked. In contrast, the detection device 10 of the present embodiment can determine the offset of the internal clock even in an environment where GPS and the Internet cannot be used.

[0027] The configuration of the detection device 10 will be described with reference to FIG. 2. FIG. 2 is a diagram showing a configuration example of the detection device according to the first embodiment.

[0028] As shown in FIG. 2, the detection device 10 includes an oscillation unit 11, a vibration reception unit 12, a clock unit 13, a control unit 14, and a storage unit 15. Further, the detection device 10 may have a communication unit (for example, a network interface card) for performing wired or wireless data communication.

[0029] The oscillation unit 11 is a device that generates vibrations (including sound) of a specified frequency. For example, the oscillation unit 11 is a vibrator or a speaker.

[0030] The vibration receiving unit 12 is a device that detects vibrations (including sound). For example, the vibration receiving unit 12 is a vibration sensor or a microphone.

[0031] The clock unit 13 is a device that functions as an internal clock. For example, the clock unit 13 includes a crystal oscillator and an oscillation circuit. The clock unit 13 outputs the current time.

[0032] The control unit 14 is a processing unit that controls the entire detection device 10. The control unit 14 is an arithmetic device such as a CPU (Central Processing Unit) equipped with a processor or a microcomputer. The control unit 14 has a determination unit 141, a measurement unit 142, and a correction unit 143.

[0033] The determination unit 141 determines the mode based on whether the time measured by the measurement unit 142 is longer than a specified interval time. The determination unit 141 determines whether the mode of the detection device 10 is either the pre-installation mode or the post-installation mode. The measurement unit 142 measures the time from when the oscillation unit 11 generates vibrations until the vibration receiving unit 12 detects the vibrations. When it is determined that the correction unit 143 is in a specific mode (for example, the post-installation mode described later), the correction unit 143 determines whether to correct the deviation of the internal clock based on the reference time, and corrects the internal clock as necessary.

[0034] In this way, the detection device 10 has a plurality of modes according to the positional relationship with other detection devices 10. By changing the processing related to the correction of the deviation of the internal clock according to the mode, the detection device 10 can perform time synchronization considering the positional relationship between the plurality of sensors.

[0035] The storage unit 15 stores various data and various programs executed by the control unit 14. For example, the storage unit 15 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a flash memory. The storage unit 15 stores data obtained during the process when the control unit 14 executes various processes, processing results obtained by executing various processes, and various data generated in the processes executed by the detection device 10.

[0036] The storage unit stores the interval information 151. The interval information 151 is a predefined interval time. Details of the interval time will be described later.

[0037] Here, a plurality of arrangement examples of the detection device 10 and examples of the operation of the detection system 1 in each arrangement example will be described.

[0038] [Arrangement Example 1: Two Detection Devices in Proximity] FIG. 3 is a diagram showing an arrangement example of the detection device. As shown in FIG. 3, before the operation of the detection system 1 starts, the detection device 10a and the detection device 10b are arranged so as to be in proximity to each other. Here, "in proximity" means that the distance between the devices is sufficiently small, including the case where the distance between the devices is 0, that is, the devices are in close contact with each other.

[0039] FIG. 4 is a diagram showing an operation example of the detection system corresponding to the arrangement example of FIG. 3. In the diagrams showing operation examples including FIG. 4, a solid-line rectangle and a dashed-line rectangle are arranged on a straight line indicating the time series corresponding to each detection device 10. The solid-line rectangle means the occurrence of vibration. Also, the dotted-line rectangle means the detection of vibration. Also, the symbol with a number after t represents the time. Also, a subtraction such as txxx - tyyy represents the length of time from time txxx to time yyy (however, xxx and yyy are numbers).

[0040] Detection devices 10a and 10b generate vibrations every time a time-related condition is satisfied. The time-related condition may be that a cycle time has elapsed since the detection device detected vibrations, or that a cycle time determined based on a preset time has elapsed, or that the time set by a timer has arrived. In this embodiment, it is assumed that detection devices 10a and 10b generate vibrations every predetermined cycle time. The cycle time may be a short time such as several seconds (for example, 2 seconds or 3 seconds), or a long time such as several tens of minutes or more (for example, 30 minutes or 60 minutes). In FIG. 4, the cycle time is 2 seconds. Also, it is assumed that 1 second is defined as an interval time between the time when detection device 10a generates vibrations and the time when detection device 10b generates vibrations.

[0041] In this case, detection device 10b generates vibrations 1 second after detection device 10a generates vibrations, and detection device 10a generates vibrations 1 second later, and this is repeated.

[0042] As shown in FIG. 4, detection device 10a generates vibrations at t101. Also, detection device 10b detects the vibrations generated by detection device 10a at t101. Also, detection device 10b generates vibrations at t102. Also, detection device 10a detects the vibrations generated by detection device 10b at t102 at t102.

[0043] Detection device 10a measures t102 - t101. As shown in FIG. 4, if t102 - t101 is equal to the interval time, detection device 10a determines that the mode is the pre-installation mode.

[0044] At the start of operation, the detection devices 10a and 10b are at the user's hand, and the detection devices 10a and 10b are arranged to be close to each other, and it is confirmed that they are determined to be in the pre-installation mode. Thereafter, the detection devices 10a and 10b are arranged to be separated from each other (for example, arranged at positions far from each other within the plant), and shift to the post-installation mode. Here, the user may adjust the internal clock.

[0045] If t102 - t101 is shorter than the interval time, since the internal clock of the detection device 10a or the detection device 10b may not be accurate, adjustment or the like is required.

[0046] In addition, the detection device 10a may be notified of the current mode by the user or the like. If the detection device 10a is notified that the current mode is the pre-installation mode and t102 - t101 is longer than the interval time, since the internal clock of the detection device 10a or the detection device 10b may not be accurate, adjustment or the like is required.

[0047] Here, actually, even when the detection devices 10a and 10b are close to each other, a time for vibration to propagate inside the device (hereinafter, the shortest propagation time) occurs. In the previous description, the detection device 10a was assumed to ignore the shortest propagation time, but the detection device 10a may determine the mode in consideration of the shortest propagation time.

[0048] Let the shortest propagation time be ε. For example, the detection device 10a determines the mode depending on whether t102 - t101 - ε is longer or shorter than the interval time. Also, an interval time considering the shortest propagation time in advance may be set.

[0049] Assume that vibration is sound propagating in air and the air temperature is 20°C. In this case, the speed of sound is 343.59 (m / s) = 34.359 (cm / s). Also, assume that the thickness of the air layer through which sound propagates between the adjacent detection devices 10a and 10b is 1 cm. From this, the shortest propagation speed ε is as shown in Equation (1). However, the shortest propagation speed ε varies according to the shape of the detection device 10, the degree of proximity, etc.

[0050] ε = 1 (cm) / 34.359 (cm / s) = 2.91×10 -5 ≒ 30 μs (1)

[0051] In the following description, it is assumed that the detection device 10 ignores the shortest propagation time. However, the detection device 10 may perform processing in consideration of the shortest propagation time as described here.

[0052] Note that if the deviation of the internal clock that occurs when the shortest propagation time is ignored is within the range allowable in operation, the detection devices 10a and 10b at that time may be regarded as being close to each other. For example, when a deviation of the internal clock up to 60 μs (30 μs × 2) is allowed, if the detection devices 10a and 10b are arranged such that the thickness of the air layer through which sound propagates is within 2 cm (1 cm × 2), the detection devices 10a and 10b are regarded as being close to each other.

[0053] [Arrangement Example 2: Two Detection Devices are Separated] FIG. 5 is a diagram showing an arrangement example of the detection devices. As shown in FIG. 5, during the operation of the detection system 1, the detection devices 10a and 10b are arranged so as to be separated from each other.

[0054] FIG. 6 is a diagram showing an operation example of the detection system corresponding to the arrangement example of FIG. 5. Similar to FIG. 4, the cycle time is 2 seconds and the interval time is 1 second. In this case, the detection device 10b generates vibration 1 second after the detection device 10a generates vibration, and then the detection device 10a generates vibration 1 second later, and this is repeated. Note that when the user does not adjust the internal clock of the detection device, it is also possible to adopt a mechanism in which the detection device 10a generates vibration, and the detection device 10b generates vibration 1 second (for example, 1 second) after the time when the detection device 10b detects the vibration generated by the detection device 10a, and the detection device 10a detects the vibration generated by the detection device 10b.

[0055] As shown in FIG. 6, the detection device 10a generates vibration at t201. Further, the detection device 10b detects the vibration generated by the detection device 10a at t202. Further, the detection device 10b generates vibration at t203. Further, the detection device 10a detects the vibration generated by the detection device 10b at t203 at t204.

[0056] The detection device 10a measures t204 - t201. If t204 - t201 is longer than the interval time, the detection device 10a determines that it is in the post-installation mode. Note that t204 - t201 is longer than s102 - t101 in FIG. 4. This is because the time for vibration to propagate becomes longer due to the separation between the detection device 10a and the detection device 10b.

[0057] The detection device 10a stores t204 - t201 as a reference time. Then, the detection device 10a continues to measure the time from when it generates vibration until it detects the vibration generated by the detection device 10b, and determines whether the internal clock of the detection device 10a or the detection device 10b is offset by comparing the measured time with the reference time.

[0058] When the measured time is different from the reference time, the detection device 10a determines that the internal clock of the detection device 10a or the detection device 10b is offset, and corrects the internal clock of one or both of them.

[0059] [Arrangement Example 3: Three Detection Devices are Proximate] The arrangement and operation in the case where there are two detection devices 10 described so far can be extended to the case where there are three or more detection devices 10.

[0060] FIG. 7 is a diagram showing an arrangement example of the detection devices. As shown in FIG. 7, before the operation of the detection system 1, the detection device 10a, the detection device 10b, and the detection device 10c are arranged close to each other.

[0061] FIG. 8 is a diagram showing an operation example of the detection system corresponding to the arrangement example of FIG. 7. The cycle time is 3 seconds. Also, the interval time between the detection device 10a and the detection device 10b is 1 second. Also, the interval time between the detection device 10a and the detection device 10c is 2 seconds. In this case, the detection device 10b generates vibration 1 second after the detection device 10a generates vibration, the detection device 10c generates vibration 1 second after that, and the detection device 10a generates vibration 1 second after that, and this is repeated.

[0062] As shown in FIG. 8, the detection device 10a generates vibration at t301. Also, the detection device 10b and the detection device 10c detect the vibration generated by the detection device 10a at t301 at t301.

[0063] Also, the detection device 10b generates vibration at t302. Also, the detection device 10a and the detection device 10c detect the vibration generated by the detection device 10b at t302 at t302.

[0064] Also, the detection device 10c generates vibration at t303. Also, the detection device 10a and the detection device 10b detect the vibration generated by the detection device 10c at t303 at t303.

[0065] The detection device 10a measures t302 - t301. If t302 - t301 is longer than the interval time between the detection device 10a and the detection device 10b, the detection device 10a determines that the mode between the detection device 10a and the detection device 10b is the post - installation mode. If t302 - t301 is equal to the interval time between the detection device 10a and the detection device 10b, the detection device 10a determines that the mode between the detection device 10a and the detection device 10b is the pre - installation mode.

[0066] The detection device 10a measures t303 - t301. If t303 - t301 is longer than the interval time between the detection device 10a and the detection device 10c, the detection device 10a determines that the mode between the detection device 10a and the detection device 10c is the post - installation mode. If t303 - t301 is equal to the interval time between the detection device 10a and the detection device 10c, the detection device 10a determines that the mode between the detection device 10a and the detection device 10c is the pre - installation mode.

[0067] In this way, the detection device 10a independently determines the mode for each of the detection device 10b and the detection device 10c. In the example of FIG. 8, both the mode between the detection device 10a and the detection device 10b and the mode between the detection device 10a and the detection device 10c are the pre - installation modes.

[0068] In this case, the detection device 10a sets a reference time for each of the detection device 10b and the detection device 10c, and determines the deviation of the internal clock based on each reference time.

[0069] [Arrangement Example 4: Two of the three detection devices are close] FIG. 9 is a diagram showing an arrangement example of the detection devices. As shown in FIG. 9, the detection device 10a and the detection device 10b are close to each other. Also, the detection device 10c is separated from the detection device 10a and the detection device 10b.

[0070] FIG. 10 is a diagram showing an operation example of the detection system corresponding to the arrangement example of FIG. 9. Similar to FIG. 8, the cycle time is 3 seconds. Also, the interval time between the detection device 10a and the detection device 10b is 1 second. Further, the interval time between the detection device 10a and the detection device 10c is 2 seconds. In this case, the detection device 10b generates vibration 1 second after the detection device 10a generates vibration, the detection device 10c generates vibration 1 second after that, and the detection device 10a generates vibration 1 second later, and this is repeated. Note that the detection device 10a may generate vibration, and the detection device 10b may generate vibration 1 second (for example, 1 second) after detecting the vibration generated by the detection device 10a, and the detection device 10a may detect the vibration generated by the detection device 10b. Also, in this case, the detection device 10c may determine its own vibration time using either or both of the information that is 2 seconds (for example, 2 seconds) after detecting the vibration generated by the detection device 10a or 1 second after detecting the vibration generated by the detection device 10b, and may vibrate. Note that the second time may be different from the first time.

[0071] As shown in FIG. 10, the detection device 10a generates vibration at t401. Also, the detection device 10b detects the vibration generated by the detection device 10a at t401 at t401. Further, the detection device 10c detects the vibration generated by the detection device 10a at t401 at t402.

[0072] The detection device 10b generates vibration at t403. Also, the detection device 10a detects the vibration generated by the detection device 10b at t403 at t403. Further, the detection device 10c detects the vibration generated by the detection device 10b at t403 at t404.

[0073] The detection device 10c generates vibration at t405. Also, the detection device 10a detects the vibration generated by the detection device 10c at t405 at t406. Further, the detection device 10b detects the vibration generated by the detection device 10c at t405 at t406.

[0074] The detection device 10a measures t403 - t401. If t403 - t401 is longer than the interval time between the detection device 10a and the detection device 10b, the detection device 10a determines that the mode between the detection device 10a and the detection device 10b is the post - installation mode. If t403 - t401 is equal to the interval time between the detection device 10a and the detection device 10b, the detection device 10a determines that the mode between the detection device 10a and the detection device 10b is the pre - installation mode.

[0075] The detection device 10a measures t406 - t401. If t406 - t401 is longer than the interval time between the detection device 10a and the detection device 10c, the detection device 10a determines that the mode between the detection device 10a and the detection device 10c is the post - installation mode. If t406 - t401 is equal to the interval time between the detection device 10a and the detection device 10c, the detection device 10a determines that the mode between the detection device 10a and the detection device 10c is the pre - installation mode.

[0076] In the example of FIG. 10, the mode between the detection device 10a and the detection device 10b is the pre - installation mode. The mode between the detection device 10a and the detection device 10c is the post - installation mode.

[0077] [Arrangement Example 5: Three detection devices are separated from each other] FIG. 11 is a diagram showing an arrangement example of detection devices. As shown in FIG. 11, the detection device 10a, the detection device 10b, and the detection device 10c are separated from each other.

[0078] FIG. 12 is a diagram showing an operation example of the detection system corresponding to the arrangement example of FIG. 11. Similar to FIG. 8, the cycle time is 3 seconds. Also, the interval time between the detection device 10a and the detection device 10b is 1 second. Further, the interval time between the detection device 10a and the detection device 10c is 2 seconds. In this case, the detection device 10b generates vibration 1 second after the detection device 10a generates vibration, the detection device 10c generates vibration 1 second after that, and the detection device 10a generates vibration 1 second after that, and this is repeated. Note that the detection device 10a may generate vibration, and the detection device 10b may generate vibration 1 second (for example, 1 second) after the detection device 10b detects the vibration generated by the detection device 10a, and the detection device 10a may detect the vibration. Also, in this case, the detection device 10c may determine its own vibration time using either or both of the information that is 2 seconds (for example, 2 seconds) after detecting the vibration generated by the detection device 10a or 1 second after detecting the vibration generated by the detection device 10b, and may vibrate.

[0079] As shown in FIG. 12, the detection device 10a generates vibration at t501. Also, the detection device 10b detects the vibration generated by the detection device 10a at t501 at t502. Further, the detection device 10c detects the vibration generated by the detection device 10a at t501 at t503.

[0080] The detection device 10b generates vibration at t504. Also, the detection device 10a detects the vibration generated by the detection device 10b at t504 at t505. Further, the detection device 10c detects the vibration generated by the detection device 10b at t504 at t506.

[0081] The detection device 10c generates vibration at t507. Also, the detection device 10a detects the vibration generated by the detection device 10c at t507 at t509. Further, the detection device 10b detects the vibration generated by the detection device 10c at t507 at t508.

[0082] The detection device 10a measures t505 - t501. If t505 - t501 is longer than the interval time between the detection device 10a and the detection device 10b, the detection device 10a determines that the mode between the detection device 10a and the detection device 10b is the post - installation mode. If t505 - t501 is equal to the interval time between the detection device 10a and the detection device 10b, the detection device 10a determines that the mode between the detection device 10a and the detection device 10b is the pre - installation mode.

[0083] The detection device 10a measures t509 - t501. If t509 - t501 is longer than the interval time between the detection device 10a and the detection device 10c, the detection device 10a determines that the mode between the detection device 10a and the detection device 10c is the post - installation mode. If t509 - t501 is equal to the interval time between the detection device 10a and the detection device 10c, the detection device 10a determines that the mode between the detection device 10a and the detection device 10c is the pre - installation mode.

[0084] In the example of FIG. 12, both the mode between the detection device 10a and the detection device 10b and the mode between the detection device 10a and the detection device 10c are the post - installation modes.

[0085] Note that when there are three or more detection devices 10, the vibration sources of the detection devices 10 may be distinguished by making the frequencies of the vibrations generated by each detection device 10 different. For example, the detection device 10a generates vibrations at 1 kHz, the detection device 10b generates vibrations at 2 kHz, and the detection device 10c generates vibrations at 3 kHz. The vibration receiving part 12 can separate and extract vibrations of a specific frequency from the detected vibrations.

[0086] [Flow of the process of the first embodiment] Using FIG. 13, the process flow of the detection device 10 will be described. It is a flowchart showing the process flow of the detection device according to the first embodiment. Here, it is assumed that the detection system 1 includes the detection device 10a and the detection device 10b. However, the arrangements of the detection device 10a and the detection device 10b are unknown. Also, it is assumed that the main body of the process of the flowchart is the detection device 10a.

[0087] As shown in FIG. 1, when the power supply of the detection device 10a is turned on, the processing starts (step S101). At this time, the mode of the detection device 10a is undetermined.

[0088] The detection device 10a generates vibrations (step S102). The vibrations generated by the detection device 10a are detected by the detection device 10b. The detection device 10a generates vibrations every time the time-related condition is satisfied.

[0089] Subsequently, the detection device 10a detects vibrations (step S103). The detection device 10a detects the vibrations generated by the detection device 10b.

[0090] The detection device 10a measures the time from when the vibrations are generated until they are detected (step S104). Here, when the mode between the detection device 10a and the detection device 10b is undetermined (step S105, No), the detection device 10a proceeds to step S106. On the other hand, when the mode between the detection device 10a and the detection device 10b is determined (step S105, Yes), the detection device 10a proceeds to step S111.

[0091] In step S106, when the measured time is not longer than the interval time (for example, equal) (step S106, No), the detection device 10a determines the mode between itself and the detection device 10b as the pre-installation mode (step S107). Then, the detection device 10a sets the interval time as the reference time (step S108). Here, cases where the measured time is shorter than the interval time and cases where the current mode is notified to the detection device 10a by the user or the like are not considered.

[0092] In this way, when the measured time is not longer than the interval time, the detection device 10a determines that the mode is the pre-installation mode in which the detection device 10a and the detection device 10b are close to each other. Then, when the detection device 10a determines that the mode is the pre-installation mode, it sets the interval time as the reference time, and determines whether to correct the deviation of the internal clocks of the detection device 10a and the detection device 10b based on the difference between the time measured after setting the reference time and the reference time. Thereby, the detection device 10a can correct the deviation of the internal clock before operation in the pre-installation mode.

[0093] Note that when the detection device 10a determines that the mode is the pre-installation mode, it may set, as the reference time, the time obtained by adding the time (the shortest propagation time) for vibration to propagate between the detection device 10a and the detection device 10b that are close to each other to the interval time, and determine whether to correct the deviation of the internal clocks of the detection device 10a and the detection device 10b based on the difference between the time measured after setting the reference time and the reference time. Thereby, the detection device 10a can perform more accurate mode determination considering the shortest propagation time.

[0094] In step S106, when the measured time by the detection device 10a is longer than the interval time (step S106, Yes), it determines that the mode between the detection device 10a and the detection device 10b is the post-installation mode (step S109). Then, the detection device 10a sets the measured time as the reference time (step S110).

[0095] In this way, when the measured time is longer than the interval time, the detection device 10a determines that the mode is the post-installation mode in which the detection device 10a and the detection device 10b are separated from each other. Then, when the detection device 10a determines that the mode is the post-installation mode, it sets the measured time as the reference time, and determines whether to correct the deviation of the internal clocks of the detection device 10a and the detection device 10b based on the difference between the time measured after setting the reference time and the reference time. Thereby, the detection device 10a can correct the deviation of the internal clock even during operation in the post-installation mode.

[0096] Also, in step S111, the detection device 10a performs correction processing based on a reference time (step S111). In the correction processing, the detection device 10a determines whether the internal clock is offset by comparing the measured time with the reference time, and corrects the internal clock if it is determined that there is an offset.

[0097] For example, when the difference between the measured time and the reference time is equal to or greater than a threshold value, the detection device 10a determines that the offset of the internal clocks of the detection device 10a and the detection device 10b is corrected. Thereby, the detection device 10a can consider the error between the measured time and the reference time by the threshold value.

[0098] In step S112, when the detection device 10a continues to operate (step S112, Yes), it waits until the conditions related to time are satisfied (step S113), and returns to step S102 to repeat the processing.

[0099] When the detection device 10a does not continue to operate (step S112, No), it ends the processing. The detection device 10a does not continue to operate, for example, when the shutdown processing is started, or when it receives an instruction to explicitly end the processing.

[0100] In step S106, the detection device 10a may determine the installation-in-progress mode separately from the pre-installation mode and the post-installation mode. When the detection device 10a determines that it is in the installation-in-progress mode, it returns to step S102 and continues to perform mode determination.

[0101] Hereinafter, a method for determining the installation-in-progress mode will be described. However, the method for determining the installation-in-progress mode is not limited to the method described here. First, the detection device 10a checks whether the frequency of the detected vibration is the vibration with the minimum frequency among the vibrations detected after the power is turned on. If it is not the minimum frequency, the detection device 10a returns to step S102.

[0102] In addition, when the detected vibration is the vibration with the minimum frequency, the detection device 10a calculates the variation in a certain number of measured times in the past. When the variation is greater than the threshold value, the detection device 10a determines that the position of the detection device 10a or the detection device 10b is not determined, that is, it is in the installation mode.

[0103] [First Embodiment] An embodiment of the detection system 1 will be described. FIG. 14 is a diagram for explaining the first embodiment. As shown in FIG. 14, the detection system 1 is arranged in a facility including a valve 211, a valve 212, a pump 213, and a motor 214.

[0104] For example, the detection device 10a strongly collects the process (fluid) sound of the pump 213. In addition, the detection device 10b strongly collects the sound of the pump 213. Further, the detection device 10d strongly collects the sound of the motor 214. In this way, each detection device 10 strongly collects the nearby sound.

[0105] If the times are accurately synchronized, the sound collected by the detection device 10b can be subtracted from the sound collected by the detection device 10a to highlight the process sound. In addition, the detection system 1 can perform beamforming based on the sound collected by each detection device 10 and identify the position of the sound source.

[0106] [Second Embodiment] FIG. 15 is a diagram for explaining the second embodiment. Depending on the proximity to the sound source 221 in FIG. 5, the magnitude of the sound detected by each detection device 10 changes. The detection system 1 can identify the position of the sound source 221 based on the distances from the plurality of detection devices 10. Further, if the detection device 10 can detect the directivity of the sound, the detection system 1 can more accurately identify the position of the sound source 221.

[0107] [Third Embodiment] FIG. 16 is a diagram for explaining a third embodiment. As shown in FIG. 16, each detection device 10 may detect sound from a plurality of sound sources. For example, based on the sound and time difference collected by the detection device 10a and the detection device 10b, it is possible to separate the sounds of the motor 231, the pump 232, and the tank 233. Furthermore, by separating the sounds, the location where the abnormal sound occurs is specified. That is, in the third embodiment, beamforming can be executed.

[0108] [Regarding the method for correcting the internal clock] The detection device 10a can correct its internal clock according to the following procedure. Here, consider the pre-installation mode where the detection device 10a and the detection device 10b are close to each other.

[0109] First, the detection device 10a generates vibrations when its internal clock is at 0:00:00.00 (where time: minute: second). Then, the detection device 10b detects the vibrations when its internal clock is at 0:00:00.00.

[0110] Then, the detection device 10a generates vibrations when its internal clock is at 1:00:00.01 about one hour later. Then, the detection device 10b detects the vibrations when its internal clock is at 1:00:00.31. This means that the internal clocks of the detection device 10a and the detection device 10b are relatively offset by 0:00:00.30 in one hour (60 minutes).

[0111] Therefore, after this, the detection device 10a, for example, adds 0:00:00.01 to its internal clock every two minutes. Or, the detection device 10b subtracts 0:00:00.01 from its internal clock every two minutes. The detection device 10 may perform the correction (addition and subtraction) not only every two minutes but at a higher or lower frequency. Also, the detection device 10 may perform the correction by adjusting the clock of the crystal oscillator by adjusting, for example, the voltage, or by changing the division ratio of the clock of the crystal oscillator. For example, the addition and subtraction of the internal clock may be performed by adjusting the clock time of the crystal oscillator. The detection device 10 can perform the addition and subtraction in a finer order by performing the correction at a high frequency (for example, every 1 millisecond). For example, the detection device 10 can also perform addition in units of microseconds such as 100 μs + 1 μs by software processing.

[0112] In this mode, since the detection devices are in the same location, conditions such as temperature are the same. Therefore, the deviation of the internal clock is due to the individual differences of the crystal oscillator or the transmission circuit itself, and this individual difference is grasped and corrected. On the other hand, in the post-installation mode, since the locations where the detection devices are installed are different, there are cases where the temperatures of the detection devices are different. Since a time deviation occurs due to this temperature difference, etc., the time is corrected regularly in the post-installation mode. The surrounding environment such as temperature may be estimated from this correction information.

[0113] Here, when the determination unit 141 determines that the mode is the pre-installation mode, the correction unit 143 records the first deviation between the first internal clock and the second internal clock based on the difference between the time measured by the measurement unit 142 and the reference time. When the correction unit 143 is determined by the determination unit 141 that the mode is the post-installation mode, the correction unit 143 records the second deviation between the first internal clock and the second internal clock based on the difference between the time measured by the measurement unit 142 and the reference time. For example, the correction unit 143 calculates the first deviation and the second deviation and stores them in the storage unit 15 together with the time stamp. The first deviation is considered to be caused by the individual difference of the transmission circuit such as a crystal oscillator. Also, the second deviation is considered to be caused by the environment (for example, temperature) around the detection device 10. Therefore, by comparing the first deviation and the second deviation, it becomes possible to estimate the change in the surrounding environment between the pre-installation mode and the post-installation mode of the detection device 10. For example, the larger the first deviation and the second deviation are, the larger the temperature difference around the detection device 10 between the pre-installation mode and the post-installation mode is considered to be.

[0114] [System] Regarding the processing procedures, control procedures, specific names, and information including various data and parameters shown in the above documents and drawings, they can be arbitrarily changed unless otherwise specified.

[0115] Also, each component of each illustrated device is a functional concept, and it is not necessarily physically configured as shown in the figure. That is, the specific form of the distribution and integration of each device is not limited to that shown in the figure. In other words, all or part of it can be functionally or physically distributed and integrated in any unit according to various loads, usage situations, etc.

[0116] Furthermore, each processing function performed by each device can be realized in whole or in any part by a CPU and a program analyzed and executed by the CPU, or can be realized as hardware by wired logic.

[0117] [Hardware] Next, a hardware configuration example of the detection device 10 will be described. FIG. 17 is a diagram for explaining the hardware configuration example.

[0118] As shown in FIG. 17, the detection device 10 includes a communication device 100a, an HDD 100b, a memory 100c, and a processor 100d. Also, each part shown in FIG. 17 is interconnected by a bus or the like.

[0119] The communication device 100a is a network interface card or the like and communicates with other devices. The HDD 100b stores a program for operating the functions shown in FIG. 2 and a DB.

[0120] The processor 100d reads a program for executing the same processing as each processing unit shown in FIG. 2 from the HDD 100b or the like and expands it in the memory 100c, thereby operating a process for executing each function described in FIG. 2 and the like. For example, this process executes the same functions as each processing unit of the detection device 10. Specifically, the processor 100d reads a program having the same functions as the determination unit 141, the measurement unit 142, and the correction unit 143 from the HDD 100b or the like. Then, the processor 100d executes a process for executing the same processing as the determination unit 141, the measurement unit 142, and the correction unit 143.

[0121] In this way, the detection device 10 operates as a detection device that executes the time synchronization method by reading and executing a program. Also, the detection device 10 can read the program from a recording medium by a medium reading device and execute the read program to realize the same functions as those in the above-described embodiments. Note that the program in this other embodiment is not limited to being executed by the detection device 10. For example, the present invention can be similarly applied when another computer or server executes the program, or when these cooperate to execute the program.

[0122] This program can be distributed via a network such as the Internet. Also, this program can be recorded on a computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO (Magneto-Optical disk), DVD (Digital Versatile Disc), etc., and can be executed by being read from the recording medium by a computer.

[0123] Some examples of combinations of the disclosed technical features are described below.

[0124] (1) An internal clock, An oscillation unit that generates oscillations each time a time-related condition is satisfied, A vibration receiving unit that detects vibrations, A measurement unit that measures the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the oscillations, A determination unit that determines a mode based on whether the time measured by the measurement unit is longer than a specified interval time, When it is determined that it is a specific mode, based on a reference time, it is determined whether to correct the deviation of the internal clock, and when it is determined to correct, a correction unit that corrects the internal clock, A detection device characterized by having the above. (2) An internal clock, An oscillation unit that generates oscillations each time a time-related condition is satisfied, A vibration receiving unit that detects vibrations, A time synchronization method executed by a detection device including the above, A measurement step of measuring the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the oscillations, A determination step of determining a mode based on whether the time measured by the measurement step is longer than a specified interval time, When it is determined that it is a specific mode, it is determined whether to correct the deviation of the internal clock based on a reference time. When it is determined to correct, a correction step of correcting the internal clock; A time synchronization method characterized by including. (3) An internal clock, An oscillation unit that generates oscillations every time a time-related condition is satisfied, A vibration receiving unit that detects vibrations, In a detection device including, A measurement step of measuring the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the oscillations; A determination step of determining a mode based on whether the time measured in the measurement step is longer than a specified interval time; When it is determined that it is a specific mode, it is determined whether to correct the deviation of the internal clock based on a reference time. When it is determined to correct, a correction step of correcting the internal clock; A time synchronization program characterized by causing the above to be executed. (4) A detection system having a first detection device including a first internal clock and a second detection device including a second internal clock, The first detection device, A first oscillation unit that generates oscillations every time a time-related condition is satisfied, A first vibration receiving unit that detects vibrations generated by the second detection device, A measurement unit that measures the time from when the first oscillation unit generates oscillations until the first vibration receiving unit detects the oscillations; A determination unit that determines a mode based on whether the time measured by the measurement unit is longer than a specified interval time; When it is determined that it is a specific mode, it is determined whether to correct the deviation between the first internal clock and the second internal clock based on a reference time. When it is determined to correct, a correction unit that corrects the first internal clock or the second internal clock; Having, The second detection device, A second oscillation unit that generates oscillations each time a time-related condition is satisfied having A detection system characterized by the above. (5) When the time measured by the measurement unit is not longer than the interval time, the determination unit determines that the mode is the pre-installation mode in which the first detection device and the second detection device are close to each other The detection system according to (4), characterized by the above. (6) When the determination unit determines that the mode is the pre-installation mode, the correction unit sets the interval time to the reference time, and based on the difference between the time measured by the measurement unit after setting the reference time and the reference time, determines whether to correct the deviation between the first internal clock and the second internal clock The detection system according to (4) or (5), characterized by the above. (7) When the determination unit determines that the mode is the pre-installation mode, the correction unit sets, as the reference time, the interval time plus the time for vibration to propagate between the first detection device and the second detection device that are close to each other, and based on the difference between the time measured by the measurement unit after setting the reference time and the reference time, determines whether to correct the deviation between the first internal clock and the second internal clock The detection system according to any one of (4) to (6), characterized by the above. (8) When the time measured by the measurement unit is longer than the interval time, the determination unit determines that the mode is the post-installation mode in which the first detection device and the second detection device are separated from each other The detection system according to any one of (4) to (7), characterized by the above. (9) When the correction unit determines that the mode is the post-installation mode by the determination unit, the correction unit sets the time measured by the measurement unit as the reference time, and determines whether to correct the deviation between the first internal clock and the second internal clock based on the difference between the time measured by the measurement unit after setting the reference time and the reference time. The detection system according to any one of (4) to (8), characterized in that. (10) When the difference between the time measured by the measurement unit and the reference time is equal to or greater than a threshold value, the determination unit determines that the deviation between the first internal clock and the second internal clock is corrected. The detection system according to any one of (4) to (9), characterized in that. (11) When the correction unit determines that the mode is the pre-installation mode by the determination unit, the correction unit records the first deviation between the first internal clock and the second internal clock based on the difference between the time measured by the measurement unit and the reference time, and when the correction unit determines that the mode is the post-installation mode by the determination unit, the correction unit records the second deviation between the first internal clock and the second internal clock based on the difference between the time measured by the measurement unit and the reference time. The detection system according to any one of (4) to (10), characterized in that.

Explanation of symbols

[0125] 1 Detection system 10, 10a, 10b, 10c, 10d Detection device 11 Oscillation unit 12 Vibration receiving unit 13 Clock unit 14 Control unit 15 Storage unit 141 Determination unit 142 Measurement unit 143 Correction unit 151 Interval information

Claims

1. An internal clock, An oscillation unit that generates oscillations each time a time-related condition is satisfied, A vibration receiving unit that detects vibrations, A measurement unit that measures the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the vibrations, A determination unit that determines a mode based on whether the time measured by the measurement unit is longer than a specified interval time, When it is determined that it is a specific mode, based on a reference time, a correction unit that determines whether to correct the deviation of the internal clock and, if it is determined to correct, corrects the internal clock, A detection device characterized by comprising the above.

2. An internal clock, An oscillation unit that generates oscillations each time a time-related condition is satisfied, A vibration receiving unit that detects vibrations, A time synchronization method executed by a detection device provided with the above, A measurement step of measuring the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the vibrations, A determination step of determining a mode based on whether the time measured in the measurement step is longer than a specified interval time, When it is determined that it is a specific mode, based on a reference time, a correction step of determining whether to correct the deviation of the internal clock and, if it is determined to correct, correcting the internal clock, A time synchronization method characterized by including the above.

3. An internal clock, An oscillation unit that generates oscillations each time a time-related condition is satisfied, A vibration receiving unit that detects vibrations, In a detection device provided with the above, A measurement step of measuring the time from when the oscillation unit generates oscillations until the vibration receiving unit detects the vibrations, A determination step of determining a mode based on whether the time measured in the measurement step is longer than a specified interval time; When it is determined that it is a specific mode, based on a reference time, determining whether to correct the deviation of the internal clock, and when it is determined to correct, a correction step of correcting the internal clock; A time synchronization program characterized by causing the above to be executed.

4. A detection system having a first detection device equipped with a first internal clock and a second detection device equipped with a second internal clock, The first detection device, A first oscillation unit that generates oscillations each time a time-related condition is satisfied; A first vibration receiving unit that detects vibrations generated by the second detection device; A measurement unit that measures the time from when the first oscillation unit generates oscillations until the first vibration receiving unit detects the oscillations; A determination unit that determines a mode based on whether the time measured by the measurement unit is longer than a specified interval time; When it is determined that it is a specific mode, based on a reference time, determining whether to correct the deviation between the first internal clock and the second internal clock, and when it is determined to correct, a correction unit that corrects the first internal clock or the second internal clock; And having The second detection device, A second oscillation unit that generates oscillations each time a time-related condition is satisfied Having A detection system characterized by the above.

5. When the time measured by the measurement unit is not longer than the interval time, the determination unit determines that the mode is an installation before mode in which the first detection device and the second detection device are close to each other The detection system according to claim 4, characterized by the above.

6. When the determination unit determines that the mode is the pre-installation mode, the correction unit sets the interval time to the reference time, and based on the difference between the time measured by the measurement unit after setting the reference time and the reference time, determines whether to correct the deviation between the first internal clock and the second internal clock. The detection system according to claim 5, characterized in that.

7. When the determination unit determines that the mode is the pre-installation mode, the correction unit sets, as the reference time, the interval time plus the time for vibration to propagate between the first detection device and the second detection device that are close to each other, and based on the difference between the time measured by the measurement unit after setting the reference time and the reference time, determines whether to correct the deviation between the first internal clock and the second internal clock. The detection system according to claim 5, characterized in that.

8. When the time measured by the measurement unit is longer than the interval time, the determination unit determines that the mode is the post-installation mode in which the first detection device and the second detection device are separated. The detection system according to claim 4, characterized in that.

9. When the determination unit determines that the mode is the post-installation mode, the correction unit sets the time measured by the measurement unit to the reference time, and based on the difference between the time measured by the measurement unit after setting the reference time and the reference time, determines whether to correct the deviation between the first internal clock and the second internal clock. The detection system according to claim 8, characterized in that.

10. When the difference between the time measured by the measurement unit and the reference time is equal to or greater than a threshold value, the determination unit determines to correct the deviation between the first internal clock and the second internal clock. The detection system according to claim 4, characterized in that.

11. When the mode is determined by the determination unit to be the pre-installation mode, the correction unit records a first deviation between the first internal clock and the second internal clock based on the difference between the time measured by the measurement unit and the reference time. When the mode is determined by the determination unit to be the post-installation mode, the correction unit records a second deviation between the first internal clock and the second internal clock based on the difference between the time measured by the measurement unit and the reference time. The detection system according to claim 4, characterized in that.

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