JP4093392B2 - Self-supporting network measurement system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention measures a physical quantity such as load, displacement, pressure, etc., and transmits the measured data to the central device side via a communication channel, and instructs the measurement device for measurement conditions, and performs measurement. The present invention relates to a data processing apparatus that receives processed data, a measurement system including the same, and a measurement method.
[0002]
[Prior art]
As a device that detects physical quantities such as load, displacement, pressure, acceleration, and torque as an electrical signal, there is a device called a strain gauge transducer. As a conventional example of a measurement system in which a large number of such devices are installed and measurement data measured by these devices are transmitted to a central data processing device via a cable, for example, Japanese Patent Laid-Open No. 12-211587 is cited. .
[0003]
Measurement system described in this Patent 1 1 -211587 Patent Publication, by a command from the central data processing unit performs measurement of the physical quantity at that time (the strain, temperature), the data transmission request from the data processing device It is based on transmitting measurement data to a data processing device. For this purpose, a strain gauge transducer necessary for this purpose, a strain gauge built-in transducer for realizing functions such as an individual identification function and a memory function, or a conversion module installed adjacent to the strain gauge are defined.
[0004]
This conventional apparatus is expected to have the following effects due to the above-described configuration.
(1) Since the length of the strain gauge connection cable is shortened, adverse effects due to level attenuation and noise are reduced, and measurement errors can be reduced.
(2) Since temperature correction and non-linearity correction are performed on the strain gauge converter side, the load on the data processing apparatus side can be reduced.
(3) Wiring work can be greatly reduced.
(4) Measurement at the same time is possible.
[0005]
[Problems to be solved by the invention]
However, the conventional example has the following problems. First, the measurement is started in response to the request of the central data processing apparatus, and the strain gauge converter or the conversion module only has a function of measuring data at one point at that time. In addition, transmission of measurement data to the data processing device requires repeated “request”-“transmission” for each strain gauge transducer or conversion module, and there is a limit to the data transmission speed. That is, the time required for the data transmission request and the switching time of the signal direction cannot be ignored, so that it takes a long time to receive the measurement data from many strain gauge transducers. Furthermore, since data cannot be measured autonomously on the strain gauge converter side or the conversion module side, there is a problem that measurement cannot be performed at all if the data processor stops operation for some reason.
[0006]
The present invention has been made to overcome the above-described problems. After the measurement is started, the communication path is exclusively used for transmission of measurement data so that high-speed communication can be performed. The purpose of this invention is to provide a measurement device and a measurement system that can maintain data collection even if the data processing device is temporarily stopped, can continue data collection, and does not lose the opportunity of data collection. is there.
[0007]
[Means for Solving the Problems]
A measurement system according to the present invention (Claim 1) includes a plurality of measurement devices that are arranged at a plurality of measurement points of a bridge or a building, measure distortion at the points, and have identification IDs for identifying themselves, and a measuring device with a total measuring system that Do and a data processing device connected via a communication path, and the strain sensor the measuring device, which detects a distortion of the measurement point, the measurement instruction from the data processing device Control means for receiving a signal, causing the sensor to measure distortion and storing the measured data, and monitoring the communication channel availability, and measuring data with its own identification ID when the communication channel is available Communication means for transmitting to the data processing apparatus side, the data processing apparatus transmits a parameter for the number of data collections and identification data sampling intervals with an identification ID before the start of measurement. Then, following the first step, the second step of transmitting a measurement start command to all the measuring devices all at once, and following the second step, each measuring device side exclusively uses the communication path, and the data processing device uses the measurement data. It is characterized by executing a process consisting of a third step that only receives.
[0008]
With this configuration, after the measurement is started, the communication path can be used exclusively for transmission of measurement data, and high-speed communication can be performed. In addition, even if the data processor side temporarily stops functioning for some reason after the start of measurement, the measuring device is independent and can continue to collect data, so that the opportunity for data collection is not lost. That is, the stored data is transmitted after the data processing apparatus is restored, so that the data can be made valid. In addition, it is possible to measure strain at a large number of measurement points such as bridges and buildings, and to dynamically measure load fluctuations and deformation amounts.
[0009]
In the measurement system of the present invention (claim 2), the data processing device receives measurement data from each measurement device after transmitting a measurement condition command signal to the measurement device, and an identification code attached to the data string. Is provided with a database unit for storing the measurement data received after reading.
[0010]
With such a configuration, the data processing apparatus side, after transmitting an Dan measurement command signal to the measuring device, automatically is only receiving the measurement data from the measuring device, every time a request for measurement data Therefore, high-speed communication can be performed.
[0013]
According to claim 3, wherein the measuring system has a plurality of strain sensors, a sample hold circuit for holding a signal from the sensors, respectively, for outputting switching signals from a plurality of sample-and-hold circuit in the subsequent stage It is characterized by having a switching device. Thereby, two or more sensor inputs can be performed using one measuring device, and the overall cost can be reduced. The sensor may detect the same physical quantity, or may detect two or more kinds of physical quantities such as strain and temperature.
[0014]
The measurement system according to claim 4, further comprising: an A / D converter that converts an analog signal from the sensor into a digital signal; and means for processing a digital signal output from the A / D converter. A D / A converter for converting a digital signal into an analog signal is provided, and a differential amplifier for differentially amplifying the output signal from the D / A converter and the signal from the sensor is provided on the input side of the A / D converter. It is characterized by being provided in.
[0015]
As a result, in the case of dynamic fluctuations such as distortion, a moving average offset amount is output from the D / A converter, and subtraction is performed by the differential amplifier, thereby minimizing the occurrence of offset due to temperature or the like. Can do.
[0018]
According to the measurement system and the measurement method, after the measurement is started, the communication path can be used exclusively for transmission of measurement data, and high-speed communication can be performed. Further, even if the data processing device side temporarily stops functioning for some reason after the start of measurement, the measuring device is independent and can continue to collect data, so that the opportunity for data collection is not lost. In addition, once the measurement command signal is transmitted to each measurement device on the data processing device side, it is only necessary to automatically receive measurement data from each measurement device, and it is not necessary to request measurement data one by one. Communication can be performed.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a measurement apparatus, a data processing apparatus, and a measurement system according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the system of the present invention, and shows an overall block diagram of a measurement system in the case of measuring pressure or the like at a large number of measurement points. This measurement system includes a plurality of measurement devices 1 (1 to N) installed at measurement locations, a cable 2 as a communication path for communicating measurement data connected to these measurement devices 1, and the cable 2 The data processing device 3 is connected to the measurement device 1 via the control unit 1, and instructs the measurement device to measure the measurement conditions and receives the measurement data. Note that data is exchanged at high speed between the measuring apparatus 1 and the data processing apparatus 3 by serial communication.
[0020]
FIG. 2 shows a block diagram of the measuring apparatus 1. This measuring apparatus 1 has a connector 11 connected to a cable 2 as a data communication path, a connector 10 connected to a power cable 4 from a power source (not shown), and alternating current or direct current supplied from the power cable. A power supply circuit 12 for converting the voltage into a constant voltage, a constant voltage generation circuit 13 for maintaining the voltage of the power supply circuit 12 constant, a bridge circuit 14 connected to the constant voltage generation circuit, and a detection output from the bridge circuit An amplifier circuit 15 for amplifying, a filter circuit 16 for filtering the amplified voltage, a power supply from the power supply circuit 12, and a data control unit 20 for processing a signal from the filter circuit 16, and a data control unit from the data control unit It comprises a level conversion circuit 17 for signal conversion (level conversion) of the output. The power supply circuit 12 supplies power to each part of the measuring apparatus 1, and the bridge circuit 14 is configured by a Wheatstone bridge circuit, and resistors R1 to R3 are provided on three sides. . A known strain gauge 5 whose electrical resistance changes due to variation in strain is connected via a terminal portion 18 to a position facing the resistor R2. Here, the 1-gauge method is described, but the 3-wire 1-gauge method and the 2-gauge method can also be applied by modifying some circuits.
[0021]
Here, when the bridge circuit 14 serving as a sensor is driven by the output of the power supply circuit 12 that causes a slight voltage change under the load conditions of the measuring apparatus 1 and other devices, the output of the bridge circuit 14 is output by the output voltage change of the power supply circuit 12. Therefore, the bridge circuit 14 is driven by the constant voltage output of the constant voltage generation circuit 13 having almost no output error. The sensor output from the bridge circuit 14 is amplified by the amplifier circuit 15, filtered by the filter circuit 16 as necessary, and input to the data control unit 20.
[0022]
The data control unit 20 includes a central processing unit (CPU) 21 as a control circuit that performs overall control according to a predetermined program procedure, and a RAM (Random Access) that temporarily stores measurement data from the strain gauge 5. Memory) 22, ROM (Read Only Memory) 23 storing the above program, A / D converter 25 for converting an analog signal from the filter circuit 16 into a digital signal, and serial communication having a serial communication function It consists of part 24 grade | etc.,. The data control unit 20 temporarily stores a measurement condition command from the data processing device 3, reads sensor information based on the condition, temporarily stores input data, and when the communication path is free. It has a function of transmitting to the data processing device 3. The level conversion circuit 17 provided between the serial communication unit 24 and the connector 11 performs necessary signal conversion (level conversion) in preparation for transmission / reception with the data processing device 3 located at a relatively remote place. is there. It may not be used for short-distance communication.
[0023]
FIG. 3 shows a block diagram of the data processing device 3. The hardware of the data processing device 3 can adopt a general personal computer, and the data processing device can be configured by installing a program for a specific measurement method in the personal computer. The data processing device 3 includes a control unit 30 that performs overall control, a RAM 31 that temporarily stores measurement data, a ROM 32 that stores a predetermined program in advance, and an output unit 33 that outputs measurement data such as a printer. A display unit 34 for displaying measurement data on a screen, a database unit 35 for storing measurement data, a serial communication unit 36 for serial communication with the measuring device 1 side, and a connector 37 to which the cable 2 is connected. It consists of and.
[0024]
Next, the operation of the measurement system will be described with reference to the flowcharts of FIGS. Each measuring device 1 is provided with an identification code (ID) for identifying itself, and an instruction can be given to each measuring device 1 using this identification code to set different data. It is said.
[0025]
First, in measurement, the data processing device 3 transmits setting data such as the number of data collections and data sampling intervals to each measuring device 1. These setting data can be set for each measurement test and are stored on the RAM 31. Then, these setting data are transmitted as commands from the control unit 30 to the measuring devices 1 from the serial communication unit 36 via the cable 2. In order to eliminate the time lag at the start of measurement in each measuring device 1, a simultaneous command is issued.
[0026]
Each measuring device 1 receives a signal from the data processing device 3 as described below. That is, when a command signal is received from the data processing device 3 as shown in step S1 of FIG. 4, the identification code in the received signal is compared with its own identification code as shown in step S2. If they match, the process proceeds to step S3. In step S3, setting data such as the number of collected measurement data and the data sampling interval are received from the signal sequence after the identification code, and these setting data are stored in the RAM 22 at the same time. Note that the measurement of data by the strain gauge 5 may be started immediately after the completion of reception of the measurement start command signal from the data processing device 3 as in step S3 ′, and the measurement start time is set to the data processing device 3. The data measurement may be started from that time.
[0027]
Next, the measuring apparatus 1 that has received the command measures at a designated sampling interval, and the measured measurement data is temporarily stored in the RAM 22 (see step S4). Note that this data storage process is not essential, and the data may be transmitted to the data processing apparatus immediately at the time of measurement, and the communication data may be saved as a backup. On the other hand, the data processing device 3 always monitors the communication path (cable 2) after the measurement command and waits for the arrival of the measurement data sent from each measurement device 1.
[0028]
Each measuring apparatus 1 monitors the operation status of the communication path by a polling method or the like (see step S5), and when the communication path is free as shown in step S6, the process proceeds to step S7 in FIG. The measurement data is transmitted to the data processing device 3 when the communication path is free. Here, if transmissions from the two measuring devices 1 collide by mistake at the same time, the transmission is performed again. Then, as shown in step S8, each measuring device 1 returns to step S4 to perform measurement when the set number of measurements has not been reached, and proceeds to step S9 when the set number of measurements has been reached. To automatically end data measurement. The transmission of measurement data from the measuring device 1 to the data processing device 3 is performed before the next data measurement every time data measurement is performed, but the data processing device 3 is measured after all the data is measured. You may make it transmit measurement data to.
[0029]
On the other hand, on the data processing device 3 side, the measurement data received by reading the identification code of the measuring device 1 attached to the data string sent from each measuring device 1 is temporarily stored in the RAM 31 or the database unit 35. Stored in the matrix space. The received measurement data is printed out from the output unit 33 or displayed on the screen by the display unit 34.
[0030]
Further, each measurement device 1 may further increase the reliability of data measurement by transmitting data at the end of measurement as necessary. Note that when the data processing device 3 completes the reception of the transmission data from all the measuring devices 1, the measurement ends. In addition, after the measurement start command from the data processing device 3 to each measuring device 1, even if the data processing device 3 goes down for some reason, the measuring device 1 can independently measure, monitor the communication path, and transmit the measurement data. Therefore, after the restoration, the measurement data can be transmitted from the measurement device 1 to the data processing device 3. Thereby, even if the data processing device 3 goes down, the opportunity of measurement on the measuring device 1 side is not lost.
[0031]
When the data processing device 3 completes reception of the measurement data from the measurement device 1, the measurement device 1 temporarily stores it in the RAM 22 by transmitting a “reception complete” signal to the measurement device 1 side. Data may be erased.
[0032]
As described above, in this embodiment, after the measurement is started, the communication path (cable 2) can be used exclusively for transmission of measurement data, so that high-speed communication can be performed. Further, even if the data processing device 3 temporarily stops the function for some reason after the measurement is started, the measuring device 1 has a self-supporting configuration, so that data collection can be continued automatically, and the opportunity for data collection It is possible to obtain an effective effect of not losing.
[0033]
The range of measurement TeiSo location of the present invention shown in FIG. In this measuring apparatus 1, temperature measurement is performed instead of strain measurement. In this example, a strain measurement bridge circuit 14 is transformed into a temperature measurement interface unit, and a thermistor whose resistance value changes as the temperature changes is used as the temperature sensor 6. Since other circuit configurations are the same as in the case of FIG. 2, description thereof is omitted, but after the measurement is started from the data processing device 3 as in the previous embodiment, each measuring device 1 side independently measures the temperature, The measured measurement data is automatically transmitted to the data processing device 3.
[0034]
(Second Embodiment) FIG. 7 shows a second embodiment of the measuring device, in order to enable measurements by two or more sensors in one measuring apparatus 1, the strain gauges 5a, 5b, the bridge circuit 14a, 14b, amplifier circuits 15a, 15b, filter circuits 16a, 16b are provided in parallel, and sample hold circuits 40a, 40b and a switch (multiplexer) are provided on the input side of the A / D converter 25 of the data controller 20. 41 is provided. The sample-and-hold circuits 40a and 40b realize complete simultaneity of input of each signal. Further, the signal voltage held by the sample hold circuits 40a and 40b is sequentially switched by the switch 41, and converted into a digital quantity by the A / D converter 25. Note that when the change of the input signal is slow compared to the A / D conversion time in the A / D conversion unit 25, the sample hold circuits 40a and 40b can be omitted.
[0035]
In the circuit of FIG. 7, the case of two strain gauges 5 a and 5 b has been described. However, three or more strain gauges 5 may be used, and in that case, a bridge circuit 14, an amplifier circuit 15, and a filter circuit 16 in the subsequent stage. Similarly, the sample hold circuit 40 is also increased. Further, two or more temperature sensors 6 can be provided in the measurement system using the temperature sensor 6 of FIG. In this case as well, a plurality of amplifier circuits 15 and filter circuits 16 are provided in parallel, and two sample and hold circuits 40a and 40b and a switch (on the input side of the A / D converter 25 of the data controller 20) Multiplexer 41). A strain gauge and a temperature sensor or other physical quantity detectors may be combined.
[0036]
( Third Embodiment) FIG. 8 shows a third embodiment of the measuring apparatus. In this measuring apparatus, in the circuit configuration of FIG. 2, a D / A conversion unit 26 is provided in the data control unit 20, and the output of the D / A conversion unit 26 and the output of the filter circuit 16 are differentially amplified. A differential amplifier 27 is provided.
[0037]
In the case of dynamic fluctuations such as distortion, take a moving average for a period that is one or two digits longer than the period of the waveform you want to measure and subtract from each instantaneous value to minimize the occurrence of offset due to temperature, etc. Can do. That is, the moving average offset amount is output from the D / A converter 26, subtracted by the differential amplifier 27, and the output of the differential amplifier 27 is input to the A / D converter 25. The differential amplifier 27 may be incorporated in the left front stage amplifier circuit 15. As a result, the offset amount associated with outdoor environmental changes (mainly temperature changes) can be suppressed. It is also possible to prevent a signal saturation phenomenon on the amplifier circuit 15 side.
[0038]
When the temperature change is small, this calculation process may be performed in the CPU 21. Further, since this temperature compensation is performed independently in real time in the measuring apparatus 1, it is not necessary to send temperature information to the data processing apparatus 3 arranged in the center. Therefore, the amount of data to be transmitted is reduced, which can contribute to reducing the burden on high-speed communication and the data processing device.
[0039]
( Fourth Embodiment) FIG. 9 shows a fourth embodiment of the measuring apparatus. In the measuring apparatus 1, signal transmission between data processing apparatuses is performed by optical communication means. That is, an optical / electrical converter 42 is provided in place of the level conversion circuit 17 in the measuring apparatus of FIG. 1, and an optical connector 43 is provided in place of the normal connector 11. Other configurations such as a measurement circuit and a CPU, and the operation by them are basically the same as those in FIG.
[0040]
In this measuring apparatus 1, the signal from the CPU 21 is converted into a serial signal by the serial communication unit 24, further converted into a serial optical signal by the optical / electrical conversion unit 41, and then from the optical connector 43 via the optical fiber 44. Sent to the data processor. Similarly, a signal from the data processing apparatus is input from the optical connector 43, converted into an electrical signal by the optical / electric conversion unit 42, and taken into the CPU 21. By using a signal path using an optical fiber in this way, (1) it is possible to transmit and receive restraint data, (2) there is little attenuation and long-distance communication is possible, and (3) noise resistance is improved. A large effect peculiar to optical transmission can be realized.
[0041]
By utilizing these effects and combining a CPU capable of high-speed data measurement, it is possible to measure a physical phenomenon having a higher frequency than mechanical vibration, such as an acoustic signal or an impulse signal. As a communication path used in the apparatus of the present invention, other signal transmission means such as a radio wave and an infrared pulse can be adopted in addition to a normal cable and an optical fiber cable.
[0042]
The circuit shown in each of the above embodiments is merely one example, and even if the circuit configuration is changed to obtain the same effect as that of the present invention, it is included in the scope of the present invention.
[0043]
【The invention's effect】
According to the measurement system of the first aspect of the present invention, after the start of measurement, the communication path can be used exclusively for transmission of measurement data, and high-speed communication can be performed. Further, even if the data processing device side temporarily stops functioning for some reason after the start of measurement, the measuring device is independent and can continue to collect data, so that the opportunity for data collection is not lost. And distortion of each measurement point can be measured efficiently.
[0044]
According to the measurement system of the second aspect, after the measurement command signal is once transmitted to each measurement device, it is only necessary to automatically receive the measurement data from each measurement device, and it is necessary to request the measurement data one by one. And high-speed communication can be performed.
[0046]
According to the measurement system of claim 3 , a plurality of sensors, a sample hold circuit for holding signals from each sensor, and a switch for switching and outputting signals from the plurality of sample hold circuits to the subsequent stage, Therefore, two or more sensor inputs can be made using a single measuring device, and the overall cost can be reduced.
[0047]
According to the measurement system of the fourth aspect of the present invention, the A / D converter that converts an analog signal from the sensor into a digital signal is provided, and the D / A that converts the digital signal output from the A / D converter into an analog signal. A conversion unit is provided, and a differential amplifier for differentially amplifying the output signal from the D / A conversion unit and the signal from the distortion sensor is provided on the input side of the A / D conversion unit. In the case of a dynamic fluctuation, the offset amount resulting from the moving average is output from the D / A converter and is subtracted by the differential amplifier, whereby the occurrence of an offset due to temperature or the like can be minimized.
[Brief description of the drawings]
FIG. 1 is an overall block diagram showing an embodiment of a measurement system of the present invention.
FIG. 2 is a block diagram showing an embodiment of a measuring apparatus used in the measuring system of the present invention.
FIG. 3 is a block diagram showing an embodiment of a data processing apparatus used in the measurement system of the present invention.
FIG. 4 is a flowchart for explaining an embodiment of operation control of a measurement apparatus used in the measurement system of the present invention.
FIG. 5 is a flowchart of operation control following FIG. 4;
FIG. 6 is a block diagram showing a measuring apparatus outside the scope of the present invention.
FIG. 7 is a block diagram showing a second embodiment of a measuring apparatus used in the measuring system of the present invention.
FIG. 8 is a block diagram showing a third embodiment of a measuring apparatus used in the measuring system of the present invention.
FIG. 9 is a block diagram showing a fourth embodiment of a measuring apparatus used in the measuring system of the present invention.
[Explanation of symbols]
1 Measuring device 2 Cable (communication path)
3 Data processing device 5 Strain gauge 6 Temperature sensor 14 Bridge circuit 20 Data control unit 21 CPU
22 RAM
24 serial communication unit 25 A / D conversion unit 26 D / A conversion unit 27 differential amplifier 30 control unit 35 database unit 36 serial communication unit 40 sample hold 41 switching unit 42 optical / electrical converter 43 optical connector 44 optical fiber cable

Claims (4)

A plurality of measuring devices arranged at a large number of measurement points of a bridge or a building and having identification IDs for identifying themselves;
A total measuring system that Do and a data processing device connected via a communication path with their measuring device,
A strain sensor for detecting the strain at the measurement location;
Control means for receiving a measurement command signal from the data processing device, causing the sensor to dynamically measure strain, and storing the measured data;
A communication means for monitoring a free state of the communication path and transmitting measurement data with its own identification ID to the data processing device when the communication path is free;
A first step in which the data processing device transmits a parameter of a data sampling number and a data sampling interval to which an identification ID is attached before starting measurement;
A second step of transmitting a measurement start command to the measuring devices all at once, following the first step;
Its following the second step, exclusively communication path is used by each measuring device, the measuring system for executing a process and a third step of only receives the measurement data in the data processing device. A database in which the data processing device receives measurement data from each measurement device after transmitting a measurement condition command signal to the measurement device, reads the identification code attached to the data string, and stores the received measurement data The measurement system according to claim 1, further comprising a unit . The measuring device has a plurality of strain sensors;
A sample hold circuit for holding signals from the sensors ,
Measuring system of which claim 1 or 2, wherein a switching device for switching and outputting signals from the plurality of sample and hold circuit in the subsequent stage. An A / D converter that converts an analog signal from the strain sensor into a digital signal is provided, means for processing the digital signal output from the A / D converter is provided, and the obtained digital signal is converted into an analog signal. to provide a D / a conversion unit, the D / a converter according to claim output signal and a differential amplifier for performing differential amplification of signals from the sensors are provided on the input side of the a / D converter from the unit 1 The described measurement system.

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