Wireless vibration sensor

Abstract

The objective is to provide a wireless vibration sensor that can contribute to reducing the amount of data transferred. [Solution] The above-mentioned problem is solved by a wireless vibration sensor comprising an acceleration sensor, a signal processing unit, and a communication circuit, which transmits vibration data to the outside, wherein the signal processing unit is capable of dividing the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band, and extracting a portion of the divided waveform data for each frequency band, the communication circuit transmits the partially extracted waveform data to the outside, and the signal processing unit has a frequency band switching unit that switches between frequency bands, thereby enabling processing by a microcontroller with a low operating frequency by processing only specific frequency bands.

Description

Technical Field

[0001] The present invention relates to a wireless vibration sensor disposed for each device in order to monitor the state of devices arranged in power parts such as factories, plants, vehicles, aircraft, etc.

Background Art

[0002] In factories and plants, equipment such as pumps, fans, drive motors, actuators, and valves are distributed. In order to diagnose the state of these equipment, vibration sensors are arranged for each of the equipment. As such a vibration sensor, there is one that includes a signal arithmetic processing circuit and a communication circuit, and digitally arithmetically processes the raw signal obtained by an acceleration sensor by a DSP and then transmits it externally as a wireless vibration sensor. Patent Document 1 discloses a vibration sensor configured to reduce the amount of transferred data and shorten the data transfer time by including an acceleration sensor that detects the vibration of a mechanical part, a filter processing unit that extracts a predetermined frequency band from the waveform of the detected signal, and an arithmetic processing unit that performs FFT analysis on the waveform after the filter processing to obtain spectrum data and transmitting the spectrum data to the outside.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The vibration sensor described in Patent Document 1 operates based on signals received from an information terminal and transmits spectral data to the information terminal to diagnose the condition of mechanical parts, thus contributing to a reduction in the amount of data transferred. However, for equipment installed in factories and plants, there is a demand not only for timely diagnosis of the condition but also for monitoring the condition in order to quickly detect or predict the occurrence of abnormalities. The vibration sensor described in Patent Document 1 is based on the premise of retrieving information via pull notifications and therefore cannot support push notifications. In other words, it is not suitable for monitoring. Furthermore, the vibration sensor described in Patent Document 1 performs FFT analysis on the raw vibration waveform obtained by the acceleration sensor and transmits the spectral data to an information terminal. The information terminal then uses the received spectral data to identify whether or not abnormalities such as scratches occur in machine parts and to pinpoint their location. Incidentally, in addition to the Fourier transform, it may be more effective to use the vibration amplitude transform as an analytical calculation process for analysis and diagnosis using vibration waveform data. Also, in diagnosing vibration abnormalities, it may be better to focus on the effective values ​​of velocity and displacement in addition to acceleration. Incidentally, equipment failure depends on the frequency and elapsed time of mechanical vibration, and vibration sensors need to monitor mechanical vibration across a wide frequency band. However, acquiring vibration data across a wide frequency range requires high-speed sampling and a huge amount of data. On the other hand, battery-powered wireless vibration sensors are desired to have a long battery life in order to reduce maintenance costs associated with battery replacement. To extend battery life, it is necessary to reduce the amount of transmitted data and shorten the waveform transmission time, and it is desirable to narrow down the data to what is appropriate for monitoring and diagnosing the condition of equipment. The vibration sensor described in Patent Document 1 aims to save power and extend battery life by narrowing down the transmitted data to spectral data, but as mentioned above, it is not sufficient for monitoring.

[0005] One of the problems addressed by this invention is the need to address such issues. Specifically, the objective of this invention is to provide a wireless vibration sensor that can transmit vibration data close to the raw vibration waveform of an acceleration sensor that has not undergone FFT analysis, while contributing to a reduction in the amount of data to be transferred, making it suitable for monitoring devices via push notifications of information. [Means for solving the problem]

[0006] To achieve this objective, the technical means according to the present invention comprises at least the following configurations. A wireless vibration sensor comprising an acceleration sensor, a signal processing unit, and a communication circuit, which transmits vibration data to an external source, wherein the signal processing unit is capable of dividing the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band, and extracting a portion of the divided waveform data for each frequency band, the communication circuit transmits the partially extracted waveform data to an external source, and the signal processing unit has a frequency band switching unit that switches between frequency bands, thereby enabling processing by a microcontroller with a low operating frequency by processing only specific frequency bands.

[0007] These characteristics result in the following effects: By transmitting vibration data that closely resembles the raw vibration waveform of the accelerometer to an external source, it becomes possible to utilize various elements effective for monitoring the condition of the equipment. Furthermore, by transmitting partially extracted waveform data externally, the amount of data transferred can be reduced. Additionally, because only a specific frequency band is processed, processing can be performed using a microcontroller with a low operating frequency.

[0008] Furthermore, in order to achieve the above objective, the technical means according to the present invention comprises at least the following configurations. A wireless vibration sensor comprising an acceleration sensor, a signal processing unit, and a communication circuit for transmitting vibration data to an external source, wherein the signal processing unit is capable of dividing the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band, and performing a division process to process each of the divided frequency band waveform data individually, and the communication circuit sequentially transmits the divided waveform data to an external source.

[0009] These characteristics result in the following effects: By transmitting vibration data that closely resembles the raw vibration waveform of the acceleration sensor to an external source, it becomes possible to utilize various elements effective for monitoring the condition of the equipment. Furthermore, because the segmented waveform data is transmitted sequentially to the external source, the amount of data transferred per unit of time can be reduced.

[0010] Furthermore, in order to achieve the above objective, the technical means according to the present invention comprises at least the following configurations. A wireless vibration sensor comprising an acceleration sensor, a signal processing unit, and a communication circuit for transmitting vibration data to an external source, wherein the signal processing unit is capable of performing time-division processing to divide the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band, and to sequentially process the divided waveform data for each frequency band individually, the communication circuit sequentially transmits the time-division processed waveform data to an external source, and the signal processing unit has a frequency band switching unit for switching frequency bands, and by sequentially extracting specific frequency bands and performing time-division processing, processing by a microcontroller with a low operating frequency is realized.

[0011] These characteristics result in the following effects: By transmitting vibration data that closely resembles the raw vibration waveform of the accelerometer to an external source, it becomes possible to utilize various elements effective for monitoring the condition of the equipment. Furthermore, because the time-division processed waveform data is transmitted sequentially to an external source, the amount of data transferred per unit of time can be reduced. In addition, because specific frequency bands are sequentially extracted and processed using time-division, processing can be performed using a microcontroller with a low operating frequency.

[0012] Furthermore, in order to achieve the above objective, the technical means according to the present invention comprises at least the following configurations. A wireless vibration sensor comprising an acceleration sensor, a signal processing unit, and a communication circuit, which transmits vibration data to an external location, wherein the signal processing unit is capable of performing a partial extraction process that divides the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band and extracts a portion of the divided waveform data for each of the multiple frequency bands, and the signal processing unit is capable of performing a time-division processing that divides the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band and sequentially processes the divided waveform data for each of the multiple frequency bands individually, and the communication circuit transmits the partially extracted waveform data or the time-division processed waveform data to an external location, and the partial extraction process and the time-division processing are selectively executed according to the settings.

[0013] These characteristics result in the following effects: By transmitting vibration data that closely resembles the raw vibration waveform of the acceleration sensor to an external source, it becomes possible to utilize various elements effective for monitoring the condition of the equipment. Furthermore, by transmitting partially extracted waveform data externally, or by sequentially transmitting time-division processed waveform data externally, the amount of data transferred per unit of time can be reduced. In addition, depending on the conditions required for the measurement target, it is possible to select and operate in a manner that transmits waveform data only in a specific frequency band externally, or in a manner that transmits waveform data in the entire frequency band externally. [Brief explanation of the drawing]

[0014] [Figure 1] It is a conceptual diagram of a wireless vibration sensor according to the first embodiment of the present invention. [Figure 2] It is a system configuration diagram of a wireless vibration sensor according to the first embodiment of the present invention. [Figure 3] It is a functional block diagram of a wireless vibration sensor according to the first embodiment of the present invention. [Figure 4] It is a conceptual diagram of a wireless vibration sensor according to the second embodiment of the present invention. [Figure 5] It is a conceptual diagram of a wireless vibration sensor according to the third embodiment of the present invention. [Figure 6] It is a conceptual diagram of a wireless vibration sensor according to the fourth embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0015] <First Embodiment> Hereinafter, the first embodiment of the present invention will be described based on the drawings. The following drawings are created for the purpose of explanation, and in some cases, members that are not necessary for the explanation may not be intentionally illustrated to make it easier to understand.

[0016] (Concept of the First Embodiment) FIG. 1 is a conceptual diagram of a wireless vibration sensor according to the first embodiment of the present invention. The wireless vibration sensor 100 according to the first embodiment of the present invention is composed of an acceleration sensor 1, a signal calculation processing unit 2, and a communication circuit 3, and transmits vibration data to the outside. The vibration data includes primary data (acceleration signal, velocity signal, displacement signal, etc.) and secondary data (overall value, RMS value, P-P value, Crest Factor value, analysis of main vibration frequency components, etc.) necessary for monitoring the vibration state of the device. The signal calculation processing unit 2 has functions (filtering function, envelope processing, FFT analysis, conversion of vibration values by differential and integral functions, etc.) for calculating these secondary data.

[0017] The acceleration sensor 1 can use, for example, a piezoelectric acceleration sensor. In addition to this, various sensors such as servo-type acceleration sensors, strain gauge-type acceleration sensors, frequency change-type acceleration sensors, etc. can be adopted for equipment such as pumps, fans, drive motors, actuators, valves, etc., and further, for the behavior of rotating elements supported by, for example, sliding bearings or rolling bearings, which are elements thereof. Also, for example, for a piezoelectric acceleration sensor, as its structure, a compression type, a beam type, or a shear type can be used. Thus, the type and structure of the acceleration sensor are not limited. The main focus of the present invention is to reduce the transfer data volume of vibration data in a wireless sensor equipped with a signal calculation processing circuit and a communication circuit. This is because the attributes of the acceleration sensor do not directly affect it.

[0018] The signal calculation processing unit 2 has a frequency band switching unit 21 for switching the frequency band in order to divide the raw vibration waveform obtained by the acceleration sensor 1 into waveform data for each specific frequency band. The main part of the signal calculation processing unit 2 is composed of a Micro Control Unit (MCU or microcomputer), but also includes some analog circuits. In other words, the frequency band switching unit 21 is composed of an analog filter and a digital filter.

[0019] The partial extraction processing unit 22 extracts a part of the waveform data for each of the divided multiple frequency bands. As the timing for extracting a part, it is possible to select any one of the timing immediately after frequency division, the timing of accumulating and storing in the storage area, and the timing of delivering the accumulated multiple data to the communication circuit. This will be described later. On the other hand, the communication circuit 3 transmits the waveform data that has been partially extracted to the outside. From the perspective of transmitting the waveform data of a part of the entire frequency band to the outside, it can be called a partial transmission unit. Here, a part of the frequency band means, for example, when divided into three, a low frequency band, a medium frequency band, and a high frequency band, in addition to meaning one of low frequency, medium frequency, and high frequency respectively, it may also mean two of medium frequency and high frequency, and the part means not all. The frequency bands subject to partial extraction processing can be set via user input or external input. For example, it is preferable to configure the settings so that they can be set from an external information terminal using the data reception function of the communication circuit 3 (see Figure 3).

[0020] Vibration data transmitted externally from a portion of the transmission unit is collected by a platform server equipped with various alarm functions, such as overall (OA) absolute value alarms, OA relative value alarms, spectral alarms, and vector alarms, via an information terminal (not shown) carried by a maintenance worker, or via a cloud-based or on-premise condition monitoring system. A software interface suitable for partial transmission is used between the information terminal and the data transmission unit. Details regarding the specifications of the information terminal and the software interface are not directly related to the scope of this invention and are therefore omitted.

[0021] Previously, measured acceleration data was typically uploaded directly to the platform server. In this regard, the vibration sensor described in Patent Document 1 reduces the amount of data transferred by converting acceleration data into spectral data. However, there is also a demand to monitor data other than spectral data when diagnosing vibration anomalies. The wireless vibration sensor 100 of the first embodiment has the advantage of being able to monitor raw vibration waveforms, albeit with the condition of monitoring only certain frequency bands. Furthermore, because it transmits only certain frequency bands, the amount of data transferred can be reduced. Even this limitation to certain frequency bands is still significant. This is because, depending on the type and behavior of the object being monitored, such as whether it is sliding or rolling, there is a mix of frequency bands that are necessary for monitoring and frequency bands that do not need to be monitored. Therefore, it is sufficient to extract and monitor only the frequency bands that are suitable for the object being monitored. In addition, based on the state of the device, the frequency band that needs to be monitored at the moment can be known from experience, and in that case, there is no need to transfer data from frequency bands other than that one. Rather, unnecessary bandwidth data can become noise during analysis, and excluding certain frequency bands from monitoring also serves as a form of data cleansing.

[0022] Furthermore, since the wireless vibration sensor 100 according to the first embodiment processes only a specific frequency band, the necessary processing can be performed with an inexpensive microcontroller that does not have a particularly high operating frequency. For example, it is possible to comprehensively process the entire frequency band by separating communication processing from other calculation processing in a multi-core device. However, when monitoring the status of equipment placed in power parts of factories, plants, vehicles, aircraft, etc., it is necessary to place a large number of sensors, and it is desirable to implement each sensor with an inexpensive single-core microcontroller. Because it processes only a specific frequency band, the wireless vibration sensor 100 according to the first embodiment can fully meet this requirement.

[0023] (System configuration of the first embodiment) Figure 2 is a system configuration diagram of a wireless vibration sensor according to the first embodiment of the present invention. As mentioned above, the wireless vibration sensor 100 according to the first embodiment consists of elements such as an acceleration sensor 1, a signal processing unit 2, and a communication circuit 3, and these elements are arranged as shown in Figure 2.

[0024] The acceleration sensor 1 is composed of a piezoelectric sensor. However, this is merely one example of the first embodiment, and other types of sensors such as servo-type acceleration sensors, strain gauge type acceleration sensors, and frequency-variable type acceleration sensors may also be used.

[0025] In the system configuration diagram shown in Figure 2, the vibration sensor includes a temperature sensor and a MEMS sensor as components, in addition to the piezoelectric sensor. The temperature sensor is just as important as the acceleration sensor in detecting abnormalities in equipment, and is therefore integrated into the wireless vibration sensor 100.

[0026] Although MEMS sensors are a type of acceleration sensor, they are not designed for diagnosing vibration abnormalities, but rather for detecting the operation or cessation of equipment being measured that operates intermittently. Specifically, the MEMS sensor in the wireless vibration sensor 100 according to the first embodiment recognizes the tilt and movement of the equipment being measured by detecting the amount of displacement as an electrical signal when a movable structure formed on a silicon substrate begins to displace in response to acceleration. From this, it is possible to detect that equipment being measured, which was stopped and not moving, has started to operate.

[0027] Conventionally, technologies for monitoring the status of equipment, or technologies for intermittently performing monitoring using wireless vibration sensors, have existed. However, such technologies only begin monitoring of measurement equipment under abnormal conditions when, for example, a large vibration exceeding a predetermined threshold is detected, and do not monitor measurement equipment during normal operation. The wireless vibration sensor 100 according to the first embodiment, which starts monitoring using a MEMS sensor, also performs monitoring during normal operation.

[0028] Normal operation can encompass microscopic conditions where no immediate problems occur, or even conditions where no abnormalities are noticeable to the human eye. Recently, advancements in AI technology have made it possible to detect early signs of malfunctions by continuously monitoring trend data and employing machine learning. Therefore, starting monitoring from the moment the measurement equipment begins operation using MEMS sensors is highly significant. On the other hand, operating wireless vibration sensors at full capacity while the measurement equipment is stopped results in wasted power. For example, by operating the MEMS sensor in ECO mode (low power consumption mode) and then switching to normal mode (normal power consumption mode) after detecting the equipment's operation, the battery consumption of the wireless vibration sensor 100 can be reduced.

[0029] The vibration waveform data detected by the piezoelectric sensor is converted from analog to digital (A / D) through an analog circuit called an LPF (low-pass filter), and the resulting digital signal is received by an MCU (microcontroller) via SPI (Serial Peripheral Interface) communication. Within the MCU, high-pass filter (HPF) processing is performed by digital processing. The LPF, A / D converter, and HPF constitute a frequency band switching unit 21 that switches between frequency bands. Thus, the frequency band switching unit 21 in the wireless vibration sensor 100 according to the first embodiment is composed of analog and digital circuits, as shown in Figure 2.

[0030] Furthermore, the MCU also performs a partial extraction process to extract waveform data only from specific frequency bands that are subject to switching. Specifically, it temporarily stores only the data from those specific frequency bands in internal memory. For other frequency bands that are not included in the temporary storage process as part of the partial extraction, even if the waveform data itself is not temporarily stored, if other processing is performed, such as the generation of trend data, that data may also be temporarily stored.

[0031] Since only specific frequency bands need to be processed for storage, the computational burden on the microcontroller is reduced. In addition to storage processing, it is also possible to enable only a portion of the high-pass filter (HPF) within the microcontroller, so that data in frequency bands other than the specific band is not processed at all, including temporary storage. By configuring it in this way, it is possible to further reduce the computational burden and power consumption.

[0032] Communication circuit 3 consists of a transmitting circuit and a receiving circuit. In this respect, it is preferable to implement the communication between the MCU and communication circuit 3 using SPI, which enables bidirectional simultaneous communication. The transmitting circuit constitutes the communication circuit in this invention, which transmits partially extracted waveform data to an external source.

[0033] Based on the requirements for wireless sensors, the wireless vibration sensor 100 according to the first embodiment includes a charging IC that receives power from a USB Type-C port in addition to a Li-ion battery. As a modification, it is conceivable that energy harvesting technology could be used, taking advantage of the characteristics of a vibration sensor, which is constantly in a vibrating environment.

[0034] Efficient operation is achieved by supplying power from the battery system to both the digital circuit system, including MEMS sensors, and the analog circuit system, such as piezoelectric sensors and LPFs, via LDOs.

[0035] (Functional block of the first embodiment) Up to this point, we have described the general concept and system configuration of the wireless vibration sensor 100 according to the first embodiment. To aid understanding, we will now also explain the functional blocks realized by this system configuration. Figure 3 is a functional block diagram of the wireless vibration sensor according to the first embodiment of the present invention.

[0036] In the wireless vibration sensor 100 according to the first embodiment, which consists of an acceleration sensor 1, a signal processing unit 2, and a communication circuit 3, the signal processing unit 2 is composed of a frequency band switching unit 21 and a partial extraction unit 22, as described above and as shown in Figure 3. Furthermore, the acceleration sensor 1 referred to in this invention is a state monitoring acceleration sensor. However, in addition to the state monitoring acceleration sensor, the wireless vibration sensor 100 according to the first embodiment also includes a state monitoring temperature sensor and a startup detection acceleration sensor. The startup detection acceleration sensor is a MEMS sensor, which is a semiconductor type acceleration sensor.

[0037] The vibration waveform detected by the state-monitoring accelerometer is passed through an AAF (Anti-aliasing Filter). Here, the AAF, which is originally used to prevent aliasing noise, is used for a clear purpose other than undersampling: frequency division, as three types of low-pass filters with different cutoff frequencies of 1kHz, 10kHz, and 20kHz. After passing through the AAF, the waveform signal is A / D converted and then treated as four AAF-passed signals. Two signals with a cutoff frequency of 20kHz are provided: one to be extracted as the waveform data itself, and the other to be extracted as waveform data in the high-frequency band.

[0038] Referring also to Figure 2, the four AAF-passed signals are digitally processed within the MCU, which involves extracting specific frequencies using three HPFs (high-pass filters) with cutoff frequencies of 3Hz, 3Hz, and 10kHz, and outputting the entire frequency band using one HPF (high-pass filter) with a cutoff frequency of 3Hz.

[0039] As can be understood from the above, the frequency band switching unit 21, which consists of an analog filter (AAF) and a digital filter (HPF), divides the waveform data into three bands: a low frequency band of 3Hz to 1kHz, a mid-frequency band of 3Hz to 10kHz, and a high frequency band of 10kHz to 20kHz. The frequency band switching unit 21 also outputs waveform data for the entire frequency band from 3Hz to 20kHz.

[0040] Waveform data for the entire frequency band, as well as waveform data for the divided low, medium, and high frequency bands, are stored in internal memory. For high-frequency band waveform data, both the raw waveform data and envelope-processed waveform data are stored. Furthermore, trend analysis is performed on the medium and high frequency bands, and RMS values, peak values, cleavage, etc., are calculated and stored. While spectral analysis, orbit & waveform analysis, and polar analysis may also be performed in addition to trend analysis, it is more practical to configure the wireless vibration sensor to have only a certain level of analysis capabilities. It is envisioned that various analyses other than trend analysis will be performed by an independent analysis device that receives data transmission from the wireless vibration sensor 100.

[0041] If the system is configured to only transmit FFT-analyzed data externally, it becomes difficult to perform other data analyses. However, the wireless vibration sensor 100 according to the first embodiment transmits data that is close to the raw waveform data (albeit in a segmented form), allowing more analyses to be performed by external analysis equipment.

[0042] As mentioned above, the data storage area includes storage areas for waveform data for each frequency band, envelope-processed waveform data, trend-analyzed data, and waveform data for all frequency bands. However, not all of this data is always stored. In other words, the microcontroller performs a process to temporarily store only the waveform data for the specific frequency band to be switched in its internal memory. This process is called partial extraction. Therefore, the signal calculation processing unit 2, which is located after the frequency band switching unit 21, becomes the partial extraction processing unit 22, as shown in Figure 3.

[0043] The example of partial extraction described here assumes that waveform data only within a specific frequency band is saved. However, as a variation, partial extraction can also be achieved by saving all waveform data but selecting only the waveform data within a specific frequency band as the data transmitted externally by the communication circuit 3. In either case, it is possible to reduce the amount of vibration data transferred.

[0044] Furthermore, the system may be configured to perform selection at a frequency band switching stage, even before selection at the storage stage or the external transmission stage. Since the HPF shown in Figure 3 is composed of a digital filter, by narrowing down the processing performed as software processing, it is possible to perform selection that limits the processing itself to only a specific frequency band, or selection that limits the A / D conversion processing to only a specific frequency band. By configuring it in this way, it is possible to reduce not only the amount of data transferred but also the amount of computational processing. This is a particularly advantageous effect when processing with a microcontroller operating at a low frequency.

[0045] <Second Embodiment> A second embodiment of the present invention will now be described. Figure 4 is a conceptual diagram of a wireless vibration sensor according to the second embodiment of the present invention. The wireless vibration sensor 100A according to the second embodiment of the present invention consists of an acceleration sensor 1, a signal processing unit 2A, and a communication circuit 3A, and transmits vibration data to an external source.

[0046] The acceleration sensor 1 is a piezoelectric acceleration sensor, similar to the wireless vibration sensor in the first embodiment. However, it is also possible to use a wide variety of other acceleration sensors, and this is also the same as in the first embodiment.

[0047] The signal processing unit 2A includes a frequency band division unit 21A for dividing the raw vibration waveform obtained by the acceleration sensor 1 into waveform data for each specific frequency band. The main part of the signal processing unit 2A is composed of a microcontroller, but it also includes some analog circuits, and the frequency band division unit 21A is composed of an analog filter and a digital filter, as in the first embodiment.

[0048] The parallel processing unit 22A processes waveform data for each of the divided frequency bands simultaneously. The waveform data for each frequency band, processed simultaneously, is sequentially transmitted to the outside by the communication circuit 3A. For this reason, the communication circuit 3A can be described as a sequential transmission unit.

[0049] The vibration data transmitted from the sequential transmission unit to the outside is collected by a platform server via an information terminal or via a cloud-based or on-premise condition monitoring system. The wireless vibration sensor 100A according to the second embodiment transmits vibration data that is close to the raw vibration waveform of the acceleration sensor and waveform data across the entire frequency band to the outside, making it possible to utilize various elements effective for monitoring the condition of equipment. Despite handling waveform data across the entire frequency band, the waveform data is divided and processed simultaneously and transmitted sequentially to the outside, making it possible to reduce the amount of data transferred per unit of time.

[0050] A characteristic feature of the wireless vibration sensor 100 according to the first embodiment is that it can perform a partial extraction process to extract a portion of the waveform data for each of the divided frequency bands, whereas a characteristic feature of the wireless vibration sensor 100A according to the second embodiment is that it can perform a division process (simultaneous parallel processing) to process the waveform data for each of the divided frequency bands individually. However, as can be seen from Figure 2, the system configuration of the second embodiment can be exactly the same as that of the first embodiment. This is because both the partial extraction process and the division process are performed by the MCU. However, in order to realize the functions of the second embodiment, the MCU needs to have a certain level of processing power or higher.

[0051] Since the system configuration is the same, the functional block diagram of the wireless vibration sensor 100A according to the second embodiment can be understood as being the same as that of the first embodiment. Therefore, the functional block of the wireless vibration sensor 100A according to the second embodiment will be explained with reference to Figure 3. The frequency band switching unit 21 and the partial extraction processing unit 22 in the first embodiment shown in Figure 3 should be understood as being equivalent to the frequency band division unit 21A and the parallel processing unit 22A in the second embodiment.

[0052] In the wireless vibration sensor 100A according to the second embodiment, which consists of an acceleration sensor 1, a signal processing unit 2A, and a communication circuit 3A, the signal processing unit 2A is composed of a frequency band division unit 21A and a division processing unit 22A. The same features as in the first embodiment include an acceleration sensor for state monitoring, a temperature sensor for state monitoring, and an acceleration sensor for startup detection.

[0053] Similar to the first embodiment, the frequency band division unit 21A, which consists of an analog filter AAF and a digital filter HPF, divides the waveform data into three bands: a low-frequency band of 3Hz to 1kHz, a mid-frequency band of 3Hz to 10kHz, and a high-frequency band of 10kHz to 20kHz. In addition, waveform data for the entire frequency band from 3Hz to 20kHz is also output.

[0054] However, in the first embodiment, waveform data other than a specific frequency band is abstracted at one of the following stages: immediately after the division process, during the storage and saving stage, or during the transmission to the communication circuit 3. In contrast, in the second embodiment, after the division process, all waveform data across multiple frequency bands is processed, all waveform data is stored and saved, and furthermore, no waveform data is abstracted when transmitted to the communication circuit 3. In other words, waveform data across all multiple frequency bands is transmitted externally.

[0055] Originally, in the wireless vibration sensor 100 according to the first embodiment, for those that transmit waveform data of only a specific frequency band when sending it to the communication circuit 3, the processing up to sending it to the communication circuit 3 is performed simultaneously, so the basic processing remains largely unchanged. Therefore, if the MCU of the wireless vibration sensor 100 according to the first embodiment has sufficient specifications, the functions of the wireless vibration sensor 100A according to the second embodiment can be implemented simply by updating the firmware. Furthermore, even in the wireless vibration sensor 100 according to the first embodiment, for those that extract only a specific frequency band when storing data, it is possible to address this through a firmware update, although the amount of update may be greater.

[0056] The wireless vibration sensor 100A according to the second embodiment transmits the divided waveform data to an external source sequentially, thereby reducing the amount of data transferred per unit of time. On the other hand, overall, it is significant because it allows external analysis devices to handle waveform data across the entire frequency band. However, because it is transmitted sequentially using time division, it is not completely real-time transmission, and it is necessary to periodically measure at arbitrary measurement intervals, thereby selectively thinning the data as needed. In situations where AI technology can detect early signs of anomalies, it is more important to acquire a large amount of waveform data across the entire frequency band, even if it is intermittent, rather than perfectly continuous waveform data, so selectively thinning the data is not a major problem.

[0057] <Third Embodiment> A third embodiment of the present invention will now be described. Figure 5 is a conceptual diagram of a wireless vibration sensor according to the third embodiment of the present invention. The wireless vibration sensor 100B according to the third embodiment of the present invention consists of an acceleration sensor 1, a signal processing unit 2B, and a communication circuit 3B, and transmits vibration data to an external source. Similar to the wireless vibration sensors according to the first and second embodiments, a wide variety of acceleration sensors can be used for the acceleration sensor 1.

[0058] The functional blocks of the wireless vibration sensor 100B according to the third embodiment will also be described, but in this description, with reference to Figure 3, the frequency band switching unit 21 and the partial extraction processing unit 22 in the first embodiment will be read as the frequency band switching unit 21B and the sequential processing unit 22B in the third embodiment.

[0059] The signal processing unit 2B has a frequency band switching unit 21B that switches frequency bands in order to divide the raw vibration waveform obtained by the acceleration sensor 1 into waveform data for each specific frequency band. In this respect, it is the same as in the first embodiment. On the other hand, it is slightly different in meaning from the second embodiment, which has a frequency band division unit 21A for dividing the raw vibration waveform obtained by the acceleration sensor 1 into waveform data for each specific frequency band. In the second embodiment, the waveform data is divided into each specific frequency band and then processed simultaneously by the parallel processing unit 22A, whereas in the third embodiment, simultaneous processing is not performed, and processing is performed only for specific frequency bands. However, these specific frequency bands are switched sequentially, such as low → medium → high → low → medium → high, so that in the medium to long term, processing is performed for waveform data of all frequency bands. In this sense, the first embodiment performs partial extraction processing, which continuously processes only a portion of the frequency bands, whereas the third embodiment, although it processes only a portion of the frequency bands at a time, performs sequential processing by periodically changing the frequency bands before processing. The difference from the second embodiment is whether it is simultaneous parallel processing or sequential processing.

[0060] Similar to the second embodiment, the third embodiment also handles all frequency bands, enabling more advanced analysis with an external analysis device. Although the amount of intermittent data decimation is larger than in the second embodiment because it is not simultaneous parallel processing, the amount of processing performed by the MCU is reduced by sequentially extracting specific frequency bands and performing time-division processing. This allows processing to be performed even with a microcontroller with a low operating frequency, which is an advantageous effect.

[0061] From what has been explained so far, it will be easy to understand that the system configuration and functional block diagram of the wireless vibration sensor 100B according to the third embodiment can be considered to be substantially the same as those of the first and second embodiments. Therefore, the functions of the wireless vibration sensor 100B according to the third embodiment can be implemented simply by updating the firmware of the wireless vibration sensor 100 according to the first embodiment. Furthermore, since it does not perform simultaneous parallel processing as in the second embodiment, the third embodiment, like the first embodiment, can be processed by a microcontroller with a low operating frequency.

[0062] <Fourth Embodiment> A fourth embodiment of the present invention will now be described. Figure 6 is a conceptual diagram of a wireless vibration sensor according to the fourth embodiment of the present invention. The wireless vibration sensor 100C according to the fourth embodiment of the present invention consists of an acceleration sensor 1, a signal processing unit 2C, and a communication circuit 3C, and transmits vibration data to an external source. As described above, a wide variety of acceleration sensors can be used for the acceleration sensor 1. The functional blocks of the wireless vibration sensor 100C according to the fourth embodiment will also be described, but as before, Figure 3 will be used as a reference and modified as appropriate.

[0063] The signal processing unit 2C has a frequency band switching unit 21C that switches frequency bands in order to divide the raw vibration waveform obtained by the acceleration sensor 1 into waveform data for each specific frequency band. In this respect, it is the same as in the first and third embodiments. Also, it has a partial extraction processing unit 22C for continuously processing only a part of the frequency band, as in the first embodiment, and a sequential processing unit 22D for processing after periodically changing the frequency band, as in the third embodiment. In other words, the fourth embodiment can be described as an embodiment that makes it possible to select and execute the functions of both the first and third embodiments.

[0064] The function can be switched via settings. For example, it would be convenient to configure the system so that settings can be configured from an external information terminal using the data reception function of the communication circuit 3 shown in Figure 3.

[0065] Although the wireless vibration sensors according to each embodiment of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and any design changes, etc., that do not depart from the spirit of the present invention are also included. For example, while each embodiment was described as monitoring equipment installed in a factory or plant, the present invention can also be applied to monitoring the status of equipment located in the power components of vehicles, aircraft, etc. Furthermore, as mentioned in the explanation of MEMS sensors, the trigger for activating the acceleration sensor is the detection of movement of the monitored object, but it may also be the detection of excessive vibration of the monitored object. Alternatively, the acceleration sensor may be configured to be activated by a more general input, such as the operation input of an information terminal. The system may also be configured to allow switching between the input-based activation mode and other modes. From this perspective, the wireless vibration sensor can be considered as being capable of transmitting vibration data to an information terminal in either push or pull mode. Furthermore, the system can be configured to automatically generate input signals and perform measurements periodically, regardless of the operation / stopping timing of the equipment being measured. This is effective for equipment that operates continuously, rather than equipment that operates intermittently. Furthermore, the system may be configured to transmit various analysis data, such as RMS values, to an external source, and even further, to transmit FFT analysis data to an external source. However, the fact that FFT analysis data is transmitted externally does not mean that this system is identical to Patent Document 1. The present invention should be clearly distinguished from the technology described in Patent Document 1, which only transmits FFT analysis data externally and therefore cannot perform various analyses on external devices. The technical concept of this invention, which reduces the amount of data transmitted by treating waveform data in a specific frequency band as only a portion, or by processing it sequentially or in parallel, should not be evaluated as merely selecting a moderate amount of data transfer as appropriate. The distinctive configuration of this invention should be correctly understood as having great technical significance when considering the technical background in this field, such as the need for continuous monitoring via push notifications and the increasing importance of analyzing various vibration waveform data in addition to FFT analysis using external analysis devices for early anomaly prediction. [Explanation of Symbols]

[0066] 100 Wireless Vibration Sensors 1. Accelerometer 2. Signal Processing Unit 21 Frequency band switching section 22 Partial extraction processing unit 3. Communication Circuit 100A Wireless Vibration Sensor 2A Signal Processing Unit 21A Frequency band division section 22A Parallel Processing Unit 3A communication circuit 100B Wireless Vibration Sensor 2B Signal Processing Unit 21B Frequency Band Switching Section 22B Sequential Processing Unit 3B Communication circuit 100C Wireless Vibration Sensor 2C signal processing unit 21C Frequency Band Switching Section 22C Partial Processing Unit 22D Sequential Processing Unit 3C communication circuit

Claims

1. A wireless vibration sensor comprising an acceleration sensor, a signal processing unit, and a communication circuit, which transmits vibration data to an external source, The signal processing unit is capable of dividing the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band, and performing a partial extraction process to extract a portion of the divided waveform data for each frequency band, and The signal processing unit is capable of performing time-division multiplexing, which divides the raw vibration waveform obtained by the acceleration sensor into waveform data for each specific frequency band, and sequentially processes each of the divided waveform data for each frequency band individually. The aforementioned communication circuit transmits partially extracted waveform data or time-division processed waveform data to an external source. The aforementioned partial extraction process and the aforementioned time-sharing process are selectively executed according to the settings. A wireless vibration sensor characterized by the following features.

2. The aforementioned signal processing unit has a function to cleanse the acquired data to match the frequency band of the vibration data to be acquired. The wireless vibration sensor according to feature 1.

3. Of the divided waveform data, at least the waveform data in the high-frequency band is envelope-processed and transmitted externally. The wireless vibration sensor according to feature 1.

4. When dividing waveform data into specific frequency bands, unnecessary bands are discarded. The wireless vibration sensor according to feature 1.

5. It is possible to take measurements periodically at any desired interval. The wireless vibration sensor according to feature 1.

6. The acceleration sensor is activated under predetermined conditions. The wireless vibration sensor according to feature 1.

7. The aforementioned predetermined conditions involve detecting the operation of the monitored object or excessive vibration. The wireless vibration sensor according to feature 6.

8. It has a storage unit for storing collected vibration data, The vibration data stored in the aforementioned storage unit can be transmitted to the information terminal in either push or pull mode. The wireless vibration sensor according to feature 1.

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