CN108931580A - The control method of sensor and sensor - Google Patents

Abstract

The present invention provides the control method of a kind of sensor and sensor.Whens the oscillator of timing generates frequency departure etc., the detection timing of test section is possible to substantially deviate the regulation moment.Sensor has：Generate the clock generation unit of clock signal；In the test section of the timing detection physical quantity based on clock signal；And control unit, the control unit are adjusted the frequency for the clock signal that clock generation unit generates, so as to become smaller at the time of the clock signal based on clock generation unit generation with the difference of external reference instant.

Description

Sensor and sensor control method

technical field

The invention relates to a sensor and a control method of the sensor.

Background technique

A sensor device including a sensing unit, a communication unit, a control unit, and a power supply unit is known (for example, refer to Patent Document 1).

Patent Document 1: Japanese Patent Laid-Open No. 2015-111091

Contents of the invention

The problem to be solved by the invention

In a sensor that synchronizes the detection timing of a physical quantity with a reference time, a timing oscillator for determining the detection timing may have a frequency deviation or the like, and the detection timing may deviate significantly from the reference time. In addition, the detection timing may deviate from the reference time due to insertion of a leap second or the like.

Technical solutions adopted to solve technical problems

In the first aspect, the sensor includes: a clock generation unit that generates a clock signal; a detection unit that detects a physical quantity at a timing based on the clock signal; and a control unit that adjusts the frequency of the clock signal generated by the clock generation unit so that The difference between the time based on the clock signal generated by the clock generation unit and the external reference time becomes small.

The control unit may adjust the frequency of the clock signal based on the difference between the time based on the clock signal and a reference time acquired from outside so that the difference between the time based on the clock signal and the reference time becomes smaller.

The control unit may increase the frequency of the clock signal when the time based on the clock signal is delayed from the reference time.

The greater the delay of the time based on the clock signal relative to the reference time, the higher the frequency of the clock signal can be increased by the control unit.

The control unit may lower the frequency of the clock signal when the time based on the clock signal is earlier than the reference time.

The greater the advance of the time based on the clock signal relative to the reference time, the lower the frequency of the clock signal can be lowered by the control unit.

The detection unit may include: a detector that generates an analog signal representing a physical quantity; and an AD conversion unit that performs AD conversion on the analog signal at a timing determined by a clock signal.

The AD conversion unit may perform AD conversion at a sampling frequency higher than a preset measurement frequency, and the detection unit may further include a filter unit that converts the digital signal obtained through the AD conversion into the preset measurement frequency. A digital signal that measures frequency.

The filter unit may include a decimation filter for attenuating frequency components of the preset measurement frequency.

The clock generator may include: a voltage controlled oscillator that generates a clock signal having a frequency corresponding to the control voltage; and a voltage generator that adjusts the control voltage based on a difference between a time based on the clock signal and a reference time.

The control unit can acquire the reference time from the outside, and make the sensor start to detect the physical quantity at the preset time based on the reference time, and generate an internal time according to the preset time and the elapsed time obtained by counting based on the clock signal, and based on the internal The difference between the time and the reference time is used to adjust the frequency of the clock signal so that the difference between the internal time and the reference time becomes smaller.

The control unit may lower the frequency of the clock signal when inserting the leap second into the reference time.

When a leap second is inserted into the reference time, the control unit may reduce the frequency of the clock signal for a predetermined period, thereby delaying the time based on the clock signal by a length corresponding to the inserted leap second.

When the control unit receives the notification that the leap second is to be inserted, it may reduce the frequency of the clock signal for the entire preset period starting from the time earlier than the time when the leap second is inserted by the preset period, thereby The time based on the clock signal is delayed by a length corresponding to the inserted leap second.

The control unit may combine the data indicating the physical quantity detected by the detection unit during the period in which the frequency of the clock signal was lowered due to the insertion of the leap second, and the information indicating that the data was detected during the period in which the frequency of the clock signal was lowered. Correspond and output.

The sensor may be arranged on the structure for detecting at least one of acceleration, inclination angle, velocity and displacement of the structure.

In mode 2, the sensor control method includes: a stage of generating a clock signal; a stage of detecting a physical quantity at a timing based on the clock signal; and adjusting the frequency of the clock signal according to the difference between the time based on the clock signal and the reference time obtained from the outside. , to reduce the difference between the time based on the clock signal and the reference time.

The above summary of the invention is not an exhaustive list of all features of the invention. Variations of these groups of features may also constitute inventions.

Description of drawings

FIG. 1 shows a schematic configuration of a monitoring system 100 according to one embodiment.

FIG. 2 schematically shows the functional structure of the sensor 40a.

FIG. 3 shows an example of a time series representing the sampling timing of the sensor 40 .

FIG. 4 shows an example of a time series representing the sampling timing of the sensor 40a.

FIG. 5 shows a flowchart of the operation of the sensor 40a.

FIG. 6 shows the sampling timing of the sensor 40 when leap seconds are processed.

FIG. 7 shows a flowchart including processing related to leap seconds.

Detailed ways

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all combinations of features described in the embodiments are essential to the technical means for solving the technical problems of the present invention.

FIG. 1 shows a schematic configuration of a monitoring system 100 according to one embodiment. The monitoring system 100 includes a structure 80 , a structure 81 , a data collection system 10 , a data collection system 11 , and a server 70 . Monitoring system 100 monitors physical quantities associated with structure 80 and structure 81 . The monitoring system 100 of this embodiment is a structure health monitoring system. For example, the monitoring system 100 monitors physical quantities related to the structure 80 and the structure 81 , and diagnoses the respective structural performances of the structure 80 and the structure 81 .

Structure 80 and structure 81 may be engineered structures. Structures 80 and 81 may include, for example, buildings, tunnels, roads, guardrails, traffic lights, utility poles, lights, airport towers, airport lighthouses, stations, railroad tracks, railway signal lights, harbor cranes, factories, steel bridges, large Dams, dikes, gates, walls, ditches, etc. The structures 80 and 81 may also include objects other than engineering structures, and earthwork structures such as embankments, slopes, and river embankments.

The data collection system 10 collects physical quantities of the structure 80 . The data collection system 10 includes a sensor 40 a , a sensor 40 b , a sensor 40 c , a sensor 40 d , a collection device 20 , a notification device 30 , a relay device 50 , and a communication line 60 . In this embodiment, the sensor 40a, the sensor 40b, the sensor 40c, and the sensor 40d may be collectively referred to as the sensor 40 in some cases.

The sensor 40 is provided on the structural body 80 . The sensor 40 is an acceleration sensor. The sensor 40 detects the vibration acceleration when the structure 80 vibrates due to an earthquake, wind, or the like. The sensor 40 also detects the inclination of the structure 80 and the like. The sensor 40 detects the inclination of the structure 80 and the like by detecting the gravitational acceleration. When the structure 80 is a building having a plurality of floors, the sensors 40 may be installed on different floors of the building. At least a part of the sensor 40 may be installed on the same floor of the building. It is also possible to arrange at least a part of the sensor 40 on the ground on which the structure 80 is fixed. Acceleration is an example of a physical quantity detected by sensor 40 . The physical quantity detected by the sensor 40 can be exemplified by an inclination angle, a speed, a displacement, and the like.

The sensor 40 is connected to the collection device 20 by a communication line 60 . Specifically, the sensor 40 is connected to the collection device 20 through the communication line 60 and the relay device 50 . The collection device 20 is connected to the notification device 30 . The communication line 60 is a communication line in a computer network. In the present embodiment, the communication line 60 is an Ethernet (registered trademark) communication line.

Data representing the acceleration detected by the sensor 40 is sent to the collecting device 20 through the communication line 60 . The collection device 20 processes the data collected from the sensors 40 . The collection device 20 analyzes the shaking of the structure 80 based on the collected data, and notifies the analysis result through the notification device 30 . For example, the collection device 20 determines whether or not an earthquake has occurred based on the shaking of the structure 80 . The collection device 20 can determine the seismic intensity of each of the plurality of floors based on the accelerations detected by the sensors 40 installed on the plurality of floors. The collection device 20 can also determine the layer displacement of the structure 80 . The collection device 20 can determine the degree of damage of each layer of the structure 80 based on the magnitude of the sloshing of each layer. The collection device 20 may notify the determination result through the notification device 30 .

The data collected by the collection device 20 is sent to the server 70 . The collection device 20 may send a part of the collected data to the server 90 through the relay device 50 and the network 90 . The collection device 20 may send the collected data to the server 70 at intervals in time. The server 70 analyzes the structure of the structure 80 based on the data received from the collection device 20 . For example, the server 70 analyzes the structure of the structure 80 over a long period of time based on the data received from the collection device 20 . For example, the safety degree of the structure 80 is judged by comparing the data at the time of construction of the structure 80 with the current data. The server 70 can measure the degree of deformation of the structure 80 to determine the emergency risk of the structure 80 . The determination result generated by the server 70 is sent to the notification device 30 and notified from the notification device 30 .

The data collection system 11 in the structure 81 has the same functions as those of the data collection system 10 . Like the data collection system 10 , the data collection system 11 analyzes the shaking of the structure 81 and notifies the result of the analysis. The server 70 analyzes the structure of the structure 81 over a long period of time based on the data received from the data collection system 11, and notifies the result of the analysis. The data collection system 11 has the same components as those included in the data collection system 10 . Therefore, illustration of the constituent elements of the data collection system 11 is omitted. A detailed description of the constituent elements included in the data collection system 11 is also omitted.

The collection device 20 has a timing function. The collecting device 20 matches the internal time measured by the timekeeping function with the external reference time. For example, the external reference time is provided by an external NTP (Network Time Protocol: Network Time Protocol) server or the like via the network 90 . The collection device 20 can synchronize the internal time with the time of the NTP server.

The sensor 40 has a timing function. The sensor 40 matches the system time counted by the timekeeping function with the external reference time. An external reference time can be provided by collecting device 20 . Specifically, the sensor 40 matches the system time with an external reference time so that the difference between the system time and the reference time falls within a preset error range. For example, the sensor 40 adjusts the system time based on the reference time received from the collecting device 20 and the delay time of communication in the communication line 60 .

The sensor 40 manages not only the system time but also an internal time for determining the measurement time of acceleration. For example, the sensor 40 updates the internal time by counting the internal time every preset time based on a clock signal for determining the measurement frequency of acceleration. The sensor 40 detects acceleration based on this clock signal. The sensor 40 transmits a sensor signal including data indicating the detected acceleration and data indicating the internal time to the collecting device 20 through the communication line 60 .

When the sensor 40 detects that the internal time is delayed from the reference time, the frequency of the clock signal for determining the measurement frequency of acceleration is increased. When the sensor 40 detects that the internal time is earlier than the reference time, the frequency of the clock signal for determining the measurement frequency of acceleration is reduced. Therefore, when the difference between the internal time and the reference time becomes large, the difference between the internal time and the reference time can be reduced, and the acceleration can be continuously measured at a substantially constant frequency. Therefore, temporal loss of data can be suppressed. In addition, by starting the detection operation of the sensor 40 from a predetermined time based on the reference time, acceleration can be detected at a predetermined detection time. In addition, the timings at which the respective sensors 40 detect acceleration can be made to coincide. Therefore, the collection device 20 can accurately determine the shaking of the structure 80 based on, for example, the acceleration of each layer of the structure 80 at the same time.

As described above, in the sensor 40, the system time is synchronized with the reference time. Therefore, when the sensor 40 detects that the internal time is delayed from the system time, the frequency of the clock signal for determining the measurement frequency of acceleration can be increased. Also, when the sensor 40 detects that the internal time is ahead of the system time, the frequency of the clock signal for determining the measurement frequency of acceleration may be reduced.

FIG. 2 schematically shows the functional structure of the sensor 40a. The sensor 40 a includes a control unit 200 , a memory 210 , a measurement unit 230 , a communication unit 290 , and a clock generation unit 250 .

The functional configuration of the sensor 40a will be described with reference to FIG. 2, but the sensor 40b, the sensor 40c, and the sensor 40d have the same configuration as the sensor 40a. Therefore, a detailed description of the sensor 40b, the sensor 40c, and the sensor 40d is omitted.

The control unit 200 controls the entire sensor 40a. The control unit 200 may be a processor. The memory 210 is a volatile memory or a nonvolatile memory. The control unit 200 uses the information stored in the memory 210 to control each unit of the sensor 40a.

The measurement unit 230 detects acceleration. The clock generation unit 250 generates a clock signal for determining the timing at which the measurement unit 230 detects acceleration. The clock generation unit 250 may generate clock signals of different frequencies. The clock generator 250 is a variable frequency oscillator. The measurement unit 230 detects acceleration at a timing based on a clock signal.

The control unit 200 may adjust the frequency of the clock signal so that the difference between the time based on the clock signal generated by the clock generation unit 250 and an external reference time becomes small. Specifically, the control unit 200 adjusts the frequency of the clock signal generated by the clock generation unit 250 based on the difference between the time based on the clock signal generated by the clock generation unit 250 and the reference time obtained from the outside, so that the time based on the clock signal is consistent with The difference between the reference time becomes smaller.

The control unit 200 increases the frequency of the clock signal when the time based on the clock signal is later than the reference time. Specifically, the control unit 200 raises the frequency of the clock signal higher as the time based on the clock signal is delayed from the reference time.

The control unit 200 lowers the frequency of the clock signal when the time based on the clock signal is earlier than the reference time. Specifically, the control unit 200 lowers the frequency of the clock signal as the time based on the clock signal is advanced by a larger amount from the reference time.

The control unit 200 may lower the frequency of the clock signal when a leap second is inserted into the reference time. For example, when a leap second is inserted into the reference time, the control unit 200 may delay the time based on the clock signal by a length corresponding to the inserted leap second by reducing the frequency of the clock signal throughout the preset period. For example, when the frequency variable range of the voltage controlled oscillator 280 is ±100 ppm, when a leap second of 1 second is inserted, the frequency of the voltage controlled oscillator 280 is set to the lowest value for 10000 seconds. Therefore, after 10000 seconds, the internal time can be substantially synchronized with the reference time. In addition, when the control unit 200 is notified that a leap second is to be inserted, it may start from a time earlier than the time when a leap second is inserted by a preset period, and decrease The frequency of the clock signal such that the time instants based on the clock signal are delayed by a length corresponding to the inserted leap second.

The measurement unit 230 has a detector 220 and an AD converter 240 . The AD converter 240 has an AD conversion unit 242 and a filter unit 244 . Detector 220 generates an analog signal representative of acceleration. The detector 220 may be a three-axis acceleration sensor.

The detector 220 has a detection means 222 , an analog processing unit 224 , and an LPF 226 . The detector 220 is a MEMS type acceleration sensor. The detection member 222 may have a MEMS device integrated on a silicon substrate, a glass substrate, an organic material, or the like. The detection member 222 has a movable electrode that can be displaced by acceleration, and outputs an analog signal corresponding to the capacitance that changes according to the displacement of the movable electrode.

The analog signal output from the detection means 222 is supplied to the analog processing unit 224 . The analog processing unit 224 performs preset processing such as amplification processing on the analog signal. LPF226 is a low pass filter. The LPF 226 substantially reduces high-frequency components to pass low frequencies. For example, when the measurement frequency is 100 Hz, it is preferable that LPF 226 has a frequency characteristic that reduces frequency components of 100 Hz or higher. The analog signal output from LPF 226 is output to AD converter 240 as an analog signal from detector 220 .

The AD converter 240 samples the analog signal supplied from the detector 220 , converts it into a digital signal, and outputs it to the control unit 200 . Specifically, AD converter 240 operates based on a clock signal supplied from clock generator 250 . More specifically, the AD conversion unit 242 performs AD conversion on the analog signal at a timing determined by a clock signal. The AD conversion unit 242 performs AD conversion at a sampling frequency higher than a preset measurement frequency. For example, the clock generator 250 supplies a clock signal having a frequency higher than the measurement frequency to the AD converter 240 .

For example, the AD conversion unit performs AD conversion of a ΔΣ (Delta-Sigma) method. The filter unit 244 converts the digital signal obtained through AD conversion into a digital signal of the measurement frequency. The filter unit 244 may include a decimation filter that attenuates frequency components of the measurement frequency. When the measurement frequency is 100 Hz, the filter unit 244 may have an attenuation peak around 100 Hz. The filter unit 244 may be provided outside the AD converter 240 .

The clock generation unit 250 has a control voltage generation unit 260 , a voltage controlled oscillator 280 , and a frequency divider 270 . The voltage controlled oscillator 280 generates a clock signal having a frequency corresponding to the control voltage. The control voltage supplied to the voltage controlled oscillator 280 is supplied from the control voltage generator 260 . The control voltage generation unit 260 generates a control voltage based on the difference between the time based on the clock signal generated by the clock generation unit 250 and the reference time. The function of the control voltage generation unit 260 may also be provided by the control unit 200 .

The clock signal generated by the voltage controlled oscillator 280 is supplied to the frequency divider 270 . The frequency divider 270 divides the frequency of the supplied clock signal by a preset frequency division ratio, and supplies it to the control unit 200 . The control unit 200 counts the time based on the frequency-divided signal of the clock signal provided by the frequency divider 270 , thereby determining an internal time for determining the time when the sensor 40 measures the acceleration.

The control unit 200 causes the sensor to start detecting acceleration at a time preset based on a reference time acquired from the outside. Specifically, the control unit 200 outputs a start signal for starting AD conversion to the AD converter 240 at a time preset based on the reference time. The control unit 200 generates an internal time based on a preset time and an elapsed time counted based on a clock signal. Specifically, the control unit 200 counts the elapsed time based on the frequency-divided signal of the clock signal supplied from the frequency divider 270 . The control unit 200 adjusts the frequency of the clock signal based on the difference between the internal time and the reference time so that the difference between the internal time and the reference time becomes smaller. For example, the control unit 200 causes the control voltage generating unit 260 to generate a control voltage based on the magnitude of the difference between the internal time and the reference time. Specifically, the control unit 200 increases the control voltage in order to increase the frequency of the clock signal when the internal time is delayed from the reference time. In addition, when the internal time of the control unit 200 is ahead of the reference time, the control voltage is reduced in order to reduce the frequency of the clock signal. Therefore, in the measurement unit 230 , the periodic measurement can be continued, and the measurement time set in advance at the reference time can be controlled to coincide with the sampling timing.

The control unit 200 stores the detection data represented by the digital signal supplied from the AD converter 240 in the memory 210 . The control unit 200 performs preset processing on the detection data to generate acceleration data representing an acceleration value. The control unit 200 uses the internal time based on the clock signal generated by the clock generation unit 250 as the detection time. The control unit 200 generates sensor data including acceleration data and time data indicating the detection time. Sensor data is an example of data representing acceleration.

In the case where the frequency of the clock signal is lowered due to the insertion of a leap second, the control unit 200 may compare the detection data detected by the measurement unit 230 during the period when the frequency of the clock signal was lowered with the Information called data detected within the period of the frequency of the signal is associated and output. For example, the control unit 200 may add a tag indicating whether or not to adjust the leap second to each piece of acceleration data.

The communication unit 290 is in charge of communicating with the collection device 20 via the communication line 60 . The communication unit 290 outputs the sensor data generated by the control unit 200 to the communication line 60 . The communication unit 290 may transmit sensor data to the collection device 20 through the communication line 60 every time the sensor 40 detects acceleration. The communication unit 290 supplies the data received through the communication line 60 to the control unit 200 . As the received data, there may be, for example, data indicating a reference time.

FIG. 3 shows an example of a time series representing the sampling timing of the sensor 40 . The time scale shown in the time series of FIG. 4 is different from the time scale of the actual time series for explanation to make the series easy to understand.

Here, it is predetermined that the sensor 40 measures the acceleration at a timing of every 10 ms from 0:00:00:00. In this case, the measurement frequency prescribed in the sensor 40 is 100 Hz. The control unit 200 supplies the AD conversion start signal to the AD conversion unit 242 at the timing when the internal time becomes 0:00:00:00 ms.

According to the specifications of the AD converter 240 and the voltage controlled oscillator 280 , it is stipulated that an output data rate of 100 Hz can be obtained from the AD converter 240 when the control voltage V0 is supplied to the voltage controlled oscillator 280 . The control unit 200 outputs a control signal for causing the control voltage generation unit 260 to output the control voltage V0 to the control voltage generation unit 260 .

After a predetermined settling time including the internal delay time of the AD conversion unit 242 and the filter unit 244 has elapsed, the AD converter 240 synchronizes with the clock signal supplied to the AD converter 240 at substantially every 10 ms. Period T, output detection data 1, 2, 3.... The control unit 200 measures the internal time based on the frequency-divided signal from the frequency divider 270 . To simplify the description here, it is assumed that the first detected data 1 is obtained at a time 00:00:00.010 after 10 ms after the detection start time 0:00:00.0 milliseconds. After that, detection data 2 is obtained at time 00:00:00.020, and detection data 3 is obtained at time 00:00:00.030.

The reference time 00:00:20.050 is received from the collection device 20 after the detection data i is obtained while the control voltage is maintained at V0. The reference time is the time notified from the collection device 20 as the reference time and the time corrected in consideration of the communication delay time between the collection device 20 and the sensor 40 . At this time, the internal time of the sensor 40 is 00:00:20.005. That is, it can be seen that the internal time is delayed by 45 ms from the reference time. In this case, the control unit 200 increases the control voltage V sent to the voltage controlled oscillator 280 by an amount corresponding to a difference of 45 ms between the reference time and the internal time. In the time series of FIG. 3 , the control unit 200 increases the control voltage from V0 to V1. Accordingly, the period of the clock signal from the clock generation unit 250 is shortened. As a result, the control unit 200 speeds up the counting of the internal time.

After the detection data i is obtained, the detection data i+1 is obtained at the internal time 00:00:20.010, the detection data i+2 is obtained at the internal time 00:00:20.020, and the detection data i+ is obtained at the internal time 00:00:20.030 3. After the control voltage reaches V1, the detection data i+1, detection data i+2, detection data i+3, . . . are obtained every period T1 shorter than 10 ms.

In the state where the control voltage is maintained at V1, the detection data j is obtained at the internal time 00:00:30.000 substantially every cycle T1, and after the detection data j+1 is obtained at the internal time 00:00:30.010, it is received from the collection device 20 Base time 00:00:30.017. The internal time of the sensor 40 at this time is 00:00:30.015. That is, it can be seen that the internal time is delayed by 2 ms from the reference time. In this case, the control unit 200 further increases the control voltage to V1'. Accordingly, the period of the clock signal from the clock generation unit 250 is further shortened. As a result, the control unit 200 further speeds up the counting of the internal time. After the control voltage reaches V1', detection data j+2, detection data j+3... are obtained substantially every period T of 10 ms. For example, if the target of the time difference between the internal time and the reference time is set within ±1 ms, the above operations are repeated until the target is within the target.

FIG. 4 shows an example of a time series representing the sampling timing of the sensor 40a. FIG. 4 shows the time series after the detection data j+3 is obtained in FIG. 3 . Here, after the detection data j+3 is obtained, the control voltage is set to be maintained at V0.

After the detection data j+3 is obtained, the detection data k is obtained at the internal time 00:00:40.000, the detection data k+1 is obtained at the internal time 00:00:40.010, and the internal time is every 10ms period T. 00:00:40.020 Get the detection data k+3.

The reference time 00:00:39.080 is received from the collection device 20 after the detection data k+2 is obtained while the control voltage is maintained at V0. At this time, the internal time of the sensor 40a is 00:00:40.025. That is, it can be seen that the internal time is 45 ms ahead of the reference time. In this case, the control unit 200 reduces the control voltage to V2. Accordingly, the period of the clock signal from the clock generation unit 250 becomes longer. As a result, the counting of the internal time by the control unit 200 is slowed down. After the control voltage reaches V2, detection data k+3, detection data k+4, detection data k+5, . . .

In the state where the control voltage is maintained at V2, the detection data m is obtained at the internal time 00:00:50.00, and after the detection data m+1 is obtained at the internal time 00:00:50.010, the reference time 00:00:50.013 is received from the collection device 20 . The internal time of the sensor 40a at this time is 00:00:50.015. That is, it can be seen that the internal time is 2 ms ahead of the reference time. In this case, the control unit 200 further reduces the control voltage to V2'. Accordingly, the cycle of the clock signal from the clock generation unit 250 becomes longer. Therefore, the counting of the internal time by the control unit 200 is further slowed down. After the control voltage reaches V2', detection data m+2, detection data m+3, ... are obtained substantially every period T of 10 ms. For example, if the target of the time difference between the internal time and the reference time is set within ±1 ms, the above operations are repeated until the target is within the target.

As shown in FIGS. 4 and 5 , the control unit 200 increases the control voltage to exceed a predetermined value V0 to increase the frequency of the clock signal when the internal time is delayed from the reference time by a predetermined time. After increasing the frequency of the clock signal, when the difference between the internal time and the reference time is less than the preset time, the control voltage is fixed at its voltage value. The control unit 200 lowers the frequency of the clock signal when the internal time is advanced by more than a preset time from the reference time. After reducing the frequency of the clock signal, when the difference between the internal time and the reference time is less than the preset time, the control voltage is fixed at its voltage value.

Referring to FIG. 3 and FIG. 4 , in order to make the description easier to understand, the case where synchronization with the reference time is achieved within an error range of milliseconds or more has been described. However, synchronization to the reference time can also be achieved within a tolerance range of less than milliseconds. In addition, a method of determining the internal time when acquiring the reference time has been described with reference to FIGS. 3 and 4 . However, when the system time of the sensor 40 is synchronized with the reference time, a system may be employed in which the internal time for measurement is compared with the system time.

FIG. 5 shows a flowchart of the operation of the sensor 40a. The processing in the flowchart of FIG. 5 is mainly executed by the operation of each unit of the sensor 40 a under the control of the control unit 200 .

In S500 of FIG. 5 , the control unit 200 synchronizes the internal time with the reference time. Specifically, when the reference time is received from the collecting device 20, the internal time is synchronized with the reference time in consideration of the time required for communication between the collecting device 20 and the sensor 40a.

In S502 of FIG. 5 , the control unit 200 determines whether or not the measurement start time has come. The control unit 200 judges whether or not the internal time coincides with a preset measurement start time. When the internal time has not reached the measurement start time, the control unit 200 waits for the measurement start time to arrive. When the measurement start time has come, in S504 , the control unit 200 outputs an AD conversion start signal to the AD conversion unit 242 to cause the clock generation unit 250 to start supplying the clock signal to the AD conversion unit 242 .

In S506 of FIG. 5 , the event that occurred is judged. Events include a detection data acquisition event generated when detection data is acquired from the filter unit 244 , a reference time acquisition event generated when a reference time is acquired from the collection device 20 , and a measurement end event.

When it is determined in S506 of FIG. 5 that a detection data acquisition event has occurred, in S510 the control unit 200 performs preset data processing on the detection data to generate sensor data. Then, in S512, the control unit 200 causes the communication unit 290 to transmit the sensor data. After the processing of S512 is completed, return to S506.

In S506 of FIG. 5 , the control unit 200 determines whether or not the delay amount of the internal time from the reference time exceeds the threshold Tth. When the delay amount of the internal time from the reference time exceeds the threshold Tth, in S522, the control unit 200 increases the control voltage supplied to the voltage controlled oscillator 280, and returns to S506.

When the delay of the internal time relative to the reference time does not exceed the threshold Tth in S520 of FIG. 5 , the control unit 200 determines whether the advance of the internal time relative to the reference time exceeds the threshold Tth in S524 . When the amount of advance of the internal time relative to the reference time exceeds the threshold Tth, in S526 the control unit 200 decreases the control voltage supplied to the voltage controlled oscillator 280 , and then returns to S506 .

When it is determined in S506 of FIG. 5 that a measurement end event has occurred, the processing of this flowchart ends. The measurement end event occurs when an instruction to end the measurement is received from the collection device, or when a measurement end switch is operated.

FIG. 6 shows the sampling timing of the sensor 40 when leap seconds are processed. In FIG. 6 , in order to make the operation sequence easy to understand and explain, the time scale is presented in a manner different from that of the actual time series. FIG. 6 shows sampling timing when notified that a leap second "8:59:60" of 1 second is inserted after 8:59:59 based on a leap second indicator received from an NTP server or the like.

For example, when the variable frequency range of the voltage-controlled oscillator 280 is ±100 ppm, the control unit 200 extends the period of the clock signal by 100 microseconds during the period of 10000 seconds starting from 10000 seconds before the time when the leap second was inserted internally. second. Therefore, at the timing after the leap second is inserted, the internal time based on the clock signal substantially coincides with the reference time. Specifically, during 10000 seconds after 6:13:20 (=2 hours, 46 minutes, and 40 seconds), the control voltage V supplied to the voltage-controlled oscillator 280 is reduced so that the period of the clock signal is T' . Here, T'=T+0.0001. Therefore, the measuring unit 230 continues to sample the acceleration at a period T'. The control unit 200 adds a leap second adjustment flag indicating "leap second adjustment is present" to the data acquired while keeping the period of the clock signal at T'. Therefore, it is possible to distinguish between data synchronized with the reference time and data in a leap second adjustment state.

As a result, the reference time of 9:00:00 after a leap second is inserted after the reference time of 8:59:59, the internal time substantially coincides with the reference time. In addition, during the period including the timing of leap second insertion, it is possible to acquire temporally continuous data whose measurement period is substantially constant.

In the case where the above processing corresponding to the leap second is not performed, the data in 1 second from 8:59:59 to 9:00:0 is output from the sensor, but the data from 8:59:60 to 9:00 Data in 1 second of minute 0 second may be missing. However, as shown in FIG. 6, by adjusting the period of the clock signal before inserting the leap second, temporally continuous data can be generated without special data manipulation for the leap second.

In FIG. 6 , when it is notified in advance that a leap second will be inserted, the processing of reducing the frequency of the clock signal before the leap second is inserted is explained. However, if there is no prior notification that a leap second will be inserted, the control unit 200 may extend the period of the clock signal by 100 microseconds within a period of 10,000 seconds when it detects that a leap second of "60 seconds" is inserted into the reference time. . Therefore, at the timing after 10000 seconds, it is possible to substantially match the internal time with the reference time.

FIG. 7 shows a flowchart including processing related to leap seconds. FIG. 7 shows operations after S506 in the flowchart of FIG. 5 . The difference between FIG. 7 and the flowchart of FIG. 5 lies in the processing including S540 and S542. Here, differences from the flowchart in FIG. 5 will be mainly described, and other descriptions will be omitted.

In the flowchart of FIG. 7 , the events judged in S506 include a leap second insertion notification event and a leap second processing event in addition to the events described with reference to FIG. 5 . The leap second insertion notification event occurs when it is notified in advance that a leap second is to be inserted based on a leap second indicator received from an NTP server or the like. The leap second processing event is generated when it is detected that a leap second is inserted into the reference time, or when a predetermined time to start clock frequency adjustment for the leap second arrives.

If it is determined in S506 that a leap second insertion notification event has occurred, in S540 the control unit 200 sets a leap second processing event to occur 10,000 seconds before the leap second insertion time. 10000 seconds before the leap second insertion time is a scheduled time to start clock frequency modulation for the leap second.

If it is determined in S506 that a leap second processing event has occurred, in S542 the control unit 200 decreases the control voltage supplied to the voltage controlled oscillator 280 for 10000 seconds to increase the period of the clock signal. Therefore, temporally continuous data can be transmitted without missing data at the time when a leap second is inserted.

Regarding the processing of the leap second, the case of inserting a positive leap second will be mainly described as an example. When inserting a negative leap second, contrary to the case of inserting a positive leap second, it is only necessary to increase the frequency of the clock signal.

According to the above-described data collection system 10, each sensor 40 adjusts the clock signal supplied to the AD conversion unit 242 according to the delay or advance relative to the reference time, so that the measurement of the sensor 40 can be performed and the internal time can be adjusted. Synchronized with the reference time. Therefore, it is possible to suppress that each sensor 40 temporarily suspends the measurement for time adjustment, or provides a measurement interval, or the measurement interval becomes extremely short.

In addition, according to the data acquisition system 10 , the sensor 40 realizes time synchronization by adjusting the conversion timing of the AD conversion unit 242 . Therefore, compared with the case where a clock signal is generated using a crystal oscillator with a fixed frequency or the like, it is possible to suppress an increase in deviation from the reference time due to accumulation of frequency errors.

In order to synchronize the measurement time with the reference time, it is conceivable that the control unit 200 supplies the AD conversion start signal to the AD conversion unit 242 one by one at a cycle T in synchronization with the reference time. However, the filter unit 244 needs a settling time of approximately time T in order to remove the folded-back signal generated by the sampling of the cycle T. Therefore, the settling time of the AD conversion unit 242 and the filter unit 244 as a whole becomes longer than the cycle T. Therefore this method cannot be used.

On the other hand, according to the sensor 40, after the AD conversion part 242 starts to operate, the sensor 40 fine-tunes the conversion timing continuously, and synchronizes time. Therefore, it is possible to continuously obtain a signal from which the foldback signal has been sufficiently removed. Thereby, since the fluctuation|variation of the zero-point output of the sensor 40 can be made small, the inclination angle can be measured with high precision.

In the monitoring system 100 , the detection timing at which the data collection system 10 detects the acceleration of the structure 80 may be synchronized with the detection timing at which the data collection system 11 detects the acceleration of the structure 81 . For example, the data collection system 11 may detect the acceleration of the structure 81 at the same time as the data collection system 10 detects the acceleration of the structure 80 .

In addition, in the monitoring system 100 , the mode in which one monitoring system 100 is provided for one structure 80 has been described. However, one monitoring system 100 may be provided for a plurality of structures.

The object to be detected by the sensor 40 is not limited to acceleration. The sensor 40 may detect various physical quantities such as a magnetic field, an electric field, light, and radiation. The number of sensors 40 included in one data collection system 10 is not limited to four, but may be two or more.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range described in the said embodiment. It is clear to those skilled in the art that various modifications and improvements can be made to the above-described embodiments. Embodiments with such changes or improvements are also included in the technical scope of the present invention, and can be understood from the description of the claims.

It should be noted that the execution order of actions, sequences, steps, stages, and other processes in the devices, systems, programs, and methods shown in the claims, description, and drawings, unless "before", "before", "Before", etc., or when the output of the previous process is used in the subsequent process, it can be implemented in any order. In the claims, description, and action flow in the drawings, for the convenience of description, "first", "then", etc. are used, but it does not mean that they must be implemented in this order.

Label description

10 Data collection system

11 Data collection system

20 collection device

30 notification device

40 sensors

50 repeater

60 communication line

70 servers

80 structures

81 structures

90 network

100 monitoring system

200 Control Department

210 memory

220 detectors

222 detection components

224 Analog Processing Department

226 LPF

230 Measurement Department

240 AD converter

242 AD conversion department

244 filter unit

250 Clock Generation Section

260 Control voltage generator

270 divider

280 Voltage Controlled Oscillator

290 Department of Communications

Claims (17)

1. a kind of sensor, which is characterized in that including：

Clock generation unit, the clock generation unit generate clock signal；

Test section, the test section detect physical quantity in the timing based on the clock signal；And

Control unit, the control unit are adjusted the frequency for the clock signal that the clock generation unit generates, so that based on described Become smaller at the time of the clock signal that clock generation unit generates with the difference of external reference instant.

2. sensor as described in claim 1, which is characterized in that

The difference of the reference instant got at the time of the control unit is according to based on the clock signal and from outside, to adjust The frequency of the whole clock signal, so as to become smaller at the time of being based on the clock signal with the difference of the reference instant.

3. sensor as claimed in claim 1 or 2, which is characterized in that

In the case that the control unit postpones at the time of being based on the clock signal than the reference instant, the clock is improved The frequency of signal.

4. sensor as claimed in claim 3, which is characterized in that

Retardation at the time of based on the clock signal relative to the reference instant is bigger, and the control unit is by the clock The frequency of signal raises higher.

5. such as described in any item sensors of Claims 1-4, which is characterized in that

In the case that the control unit shifts to an earlier date at the time of being based on the clock signal than the reference instant, the clock is reduced The frequency of signal.

6. sensor as claimed in claim 5, which is characterized in that

Lead at the time of based on the clock signal relative to the reference instant is bigger, and the control unit is by the clock The frequency of signal drops lower.

7. such as described in any item sensors of claim 1 to 6, which is characterized in that

The test section includes：

Detector, the detector maturation indicate the analog signal of the physical quantity；And

AD conversion portion, the AD conversion portion are AD converted the analog signal in the timing determined by the clock signal.

8. sensor as claimed in claim 7, which is characterized in that

The AD conversion portion carries out the AD conversion with the sample frequency for being higher than preset measurement frequency,

The test section further includes：

Filtering part, the filtering part believe the number for being converted into the measurement frequency by digital signal obtained from the AD conversion Number.

9. sensor as claimed in claim 8, which is characterized in that

The filtering part includes the decimation filter for making the frequency component decaying of the measurement frequency.

10. such as described in any item sensors of claim 1 to 9, which is characterized in that

The clock generation unit includes：

Voltage-controlled oscillator, the voltage-controlled oscillator generate the frequency clock signal corresponding with control voltage；And

Voltage generating unit, the voltage generating unit at the time of being based on the clock signal according to, with the difference of the reference instant, adjusting The control voltage.

11. sensor as claimed in claim 10, which is characterized in that

The control unit obtains the reference instant from outside,

The moment is being preset based on the reference instant, the sensor is made to start to detect the physical quantity,

Pass through the time according at the time of described preset and based on what clock signal progress timing obtained, when generating internal It carves,

Based on the difference at the internal moment and the reference instant, the frequency of the clock signal is adjusted, so that when described internal It carves and the difference of the reference instant becomes smaller.

12. such as described in any item sensors of claim 1 to 11, which is characterized in that

The control unit reduces the frequency of the clock signal in the case where that will be inserted into leap second in the reference instant.

13. sensor as claimed in claim 12, which is characterized in that

In the case that the control unit inserts leap second in the reference instant, institute is reduced in a period of entirely presetting The frequency of clock signal is stated, thus delay length corresponding with the leap second being inserted at the time of making based on the clock signal.

14. such as described in any item sensors of claim 1 to 13, which is characterized in that

The control unit is advanced by advance at the time of from than being inserted into the leap second when receiving the notice of leap second to be inserted into Start at the time of during setting it is entire it is described preset during, the frequency of the clock signal is reduced, to make to be based on Delay length corresponding with the leap second the being inserted at the time of clock signal.

15. such as described in any item sensors of claim 12 to 14, which is characterized in that

The control unit will indicate in a period of reducing the frequency of the clock signal because being inserted into the leap second as described in The data for the physical quantity that test section detects with expression are detected in a period of reducing the frequency of the clock signal This information of data is corresponded to and is exported.

16. such as described in any item sensors of claim 1 to 15, which is characterized in that

The sensor is set to structural body, in acceleration, tilt angle, speed and the displacement for detecting the structural body At least one of.

17. a kind of control method of sensor, which is characterized in that including such as next stage：

Generate the stage of clock signal；

In the stage of the timing detection physical quantity based on the clock signal；And

Adjust the frequency of the clock signal so that at the time of based on the clock signal with from outside get benchmark when The stage that the difference carved becomes smaller.