JP5126911B2 - System synchronization method for in-vehicle ground penetrating radar measuring device - Google Patents

Description

  The present invention relates to a measurement technique using a ground penetrating radar apparatus that searches an underground structure such as a cavity, a buried object, or a structure existing under a road surface while traveling on the road surface. The present invention relates to a system synchronization method for a vehicle-mounted ground penetrating radar measuring apparatus in which data, GPS position information and digital video images are linked so that information on an arbitrary place can be accurately and easily extracted.

  In order to maintain the function of the road structure and keep it in a state that does not hinder traffic, it is necessary to always perform appropriate maintenance. Conventionally, underground radar exploration has been widely used as a method for efficiently investigating road structures including pavement structures. This underground radar exploration is a non-destructive technique that visualizes underground structures with high speed and high accuracy using high-frequency electromagnetic waves. For road structures, cavities under the road surface and artificial buried objects (such as buried pipes) It is used for investigation.

  Since road structures extend over long distances, underground radar measuring devices are mounted on vehicles, and while traveling on the road surface, exploration of underground structures such as cavities and buried pipes under the road surface is being conducted. (See Patent Document 1). The position is specified by a position detecting device for a cavity search vehicle equipped with a ground penetrating radar device. In this prior art, the position detection device includes a vehicle distance meter, a first video camera that captures the situation on the side of the vehicle, a second video camera that captures the front of the vehicle, and first and second The video system includes a video recorder that records video information captured by a video camera. The distance information from the distance meter is input to the video recorder and also recorded in the data recorder of the ground penetrating radar device.

  However, in the conventional in-vehicle ground penetrating radar measurement device, the distance information of the distance meter, the video data, and the ground penetrating radar data are not accurately linked, and although a rough relationship is known, the location is identified from the video image. However, it was impossible to acquire ground radar data that corresponded exactly to the location, and even if ground radar data was specified, the acquisition point could not be determined accurately. That is, in the prior art, the distance information and video data are only a guide for finding the acquisition position of the ground radar data, and it is difficult to obtain accurate position information.

JP-A-5-87945

  The problem to be solved by the present invention is that the ground penetrating radar data measured in the in-vehicle ground penetrating radar measuring device that searches the ground structure such as a cavity under the road surface, a buried object, or a structure while traveling on the road surface. The position information by GPS and the digital video image of the radar data acquisition position are accurately linked so that information of an arbitrary place can be accurately and easily extracted.

  The present invention is equipped with a ground radar device, a distance meter, a plurality of digital video cameras, a time code generator that captures a measured elapsed time in a digital video image, and a GPS device, and is mounted on a vehicle to search under the road surface while traveling. A system synchronization method for linking measured ground penetrating radar data with GPS position information and digital video images in a middle radar measurement apparatus, and a time / distance signal for generating a distance pulse based on a reference time pulse and a distance meter Using the controller, the ground penetrating radar device is configured to record a certain number of radar waveforms for each unit distance during traveling in response to the distance pulse, and record the ground pulse data together with the time pulse as the ground radar data, For each time pulse, (a) cumulative number of time pulses, (b) cumulative distance traveled, (c) time code A synchronization file in which the superimpose time of the generator and (d) GPS coordinates are recorded is generated, and the radar waveform trace position of the ground radar data, the GPS coordinates of the synchronization file, and the superimpose are generated using the time pulse as a medium. This is a system synchronization method for an in-vehicle ground penetrating radar measuring apparatus characterized by associating time.

Here, the radar waveform trace position at the time of arbitrary pulse transmission sent from the time / distance signal controller
(1) Cumulative number of time pulses of ground penetrating radar data (2) Obtained from both accumulated distances at time pulse transmission recorded in the synchronization file. Further, the GPS coordinates and the superimpose time at an arbitrary radar waveform trace position are obtained by linear interpolation using the radar waveform trace position of the time pulse. Furthermore, using the correction coefficient obtained by dividing the actual video playback time length by the in-video superimpose time length, the video playback position at any radar waveform trace position is corrected and calculated, and any radar waveform trace of the ground radar data is calculated. Corresponding position and digital video image.

  The system synchronization method of the in-vehicle ground penetrating radar measurement apparatus according to the present invention generates a synchronization file using a time / distance signal controller, and performs measurement on the software using the synchronization file after measurement. It is possible to efficiently and accurately perform the position reproducibility of the ground penetrating radar data based on the position information by GPS and the image of the video camera. This makes it possible to obtain accurate positional information of cavities, buried pipes, and underground structures under the road surface. Based on this information, the search results are compiled into a database, which can be compared with previous search results. For this reason, it is possible to examine the development of the cavity and to select the detailed survey point after the exploration efficiently.

The conceptual diagram of the system synchronization method of the vehicle-mounted underground radar measuring device which concerns on this invention. Explanatory drawing of a subsurface exploration vehicle equipped with a ground penetrating radar measurement device. The block diagram which shows one Example of the underground radar measuring device incorporating the time and distance signal controller. Processing flow of time / distance signal controller. Timing chart of time / distance signal controller and each device. A conceptual diagram of ground penetrating radar data including time pulse information.

  The present invention is equipped with a ground penetrating radar device, an optical distance meter, a plurality of digital video cameras, a time code generator (TCG) that captures the measured elapsed time in a digital video image, and a GPS device. This is a system synchronization method for linking measured ground penetrating radar data with GPS position information and digital video images.

  In the present invention, a time / distance signal controller that generates a distance pulse based on a reference time pulse and a distance meter is used. The underground radar device receives the distance pulse based on a distance meter and records a certain number of radar waveforms for each unit distance during traveling. These radar waveform traces are configured to record as ground radar data along with the time pulses from the time and distance signal controller. Therefore, in the ground penetrating radar data, since the cumulative number of radar waveform traces and the cumulative distance from the start of measurement correspond one-to-one, the radar waveform trace position at the time pulse recording position is the radar waveform for each preset unit distance. It can be determined using the number of traces. On the other hand, in the in-vehicle PC, as shown in FIG. 1, at the time pulse transmission time t1, t2,... From the time / distance signal controller, (a) cumulative number of time pulses, (b) cumulative travel A synchronization file is generated in which the distance, (c) time code generator superimpose time, and (d) GPS coordinates are recorded. That is, in the synchronization file, the distance meter position at a certain time, the display time in the video, the longitude, latitude, and altitude by GPS are recorded at a constant time interval dt. Therefore, by processing on the software after measurement, the radar waveform trace position of the ground radar data, the GPS coordinates of the synchronization file, and the superimpose time can be synchronized at a constant time interval dt using the time pulse as a medium. This enables accurate association between the mutual data.

Here, the radar waveform trace position at the time of arbitrary time pulse transmission sent from the time / distance signal controller is
(1) Cumulative number of time pulses of ground penetrating radar data (2) Can be obtained from any one of accumulated distances at time pulse transmission recorded in a synchronization file. However, if there is a lack of time pulse recording in the ground penetrating radar data, an error occurs only in the above (1), so that the reliability can be improved by adopting both the above (1) and (2). it can.

  The GPS coordinate and the superimpose time at an arbitrary radar waveform trace position can be obtained by linear interpolation using the radar waveform trace position of the time pulse. Also, using the correction coefficient obtained by dividing the actual video playback time length by the superimposition time length in the video, the video playback position at any radar waveform trace position is corrected and calculated, and any radar waveform trace of the ground radar data is calculated. The position and the digital video image can be accurately matched.

  This makes it possible to efficiently and accurately reproduce the position information of the measured ground penetrating radar data using GPS and the position of the video camera image.

  FIG. 2 is an example of a subsurface exploration vehicle used in the present invention, and shows the arrangement state of each device by a plane and a side surface. This subsurface exploration vehicle includes a device-equipped vehicle 10 that is self-propelled and an antenna-equipped vehicle 12 that is pulled by the vehicle. The equipment-equipped vehicle 10 includes a total of three digital video cameras 14, a GPS device 16, a car navigation system (car navigation system) 18, an optical distance meter 20 that can be measured in a non-contact manner, and other necessary items. It is equipped with various control devices, displays, recording devices (hard disks), in-vehicle PCs (personal computers), etc., as well as drivers, measurers and so on. On the other hand, the antenna-equipped vehicle 12 has six sets of transmission / reception antennas 22 arranged on the left and right and the center of the low-profile carriage so that the entire lane can be measured at one time. In this configuration, power is supplied and signals are exchanged. The reason why the antenna-equipped vehicle 12 is in the trailer type is that noise from the vehicle and the device is reduced as compared with the case where the antenna-equipped vehicle 12 is integrated into the device-equipped vehicle.

  FIG. 3 shows a schematic configuration of a ground penetrating radar measuring apparatus according to the present invention. A portion surrounded by a broken line is the time / distance signal controller 30 used in the present invention.

  First, the peripheral device configuration will be described. Position information (latitude, longitude, altitude) and cumulative distance from the GPS device 16 are transmitted to the in-vehicle PC 32. The digital video image from the high-sensitivity camera system 14 on both the front and left and right sides, the map information from the car navigation system 18 and the elapsed time information from the time code generator (TCG) 34 are provided with a video capture function via the multi-viewer 36. It is sent to the in-vehicle PC 32. The three video images and the car navigation image are displayed on the liquid crystal display 38 as a four-divided screen, and the elapsed time by the time code generator 34 is also displayed on the liquid crystal display 38. Audio information from the microphone 40 is also recorded in the in-vehicle PC 32.

  The underground radar measurement system has a configuration in which two antennas 22 are connected to three underground radar devices 42, respectively. The antenna may be a bow tie type or a horn type. The mid-range radar device 42 is provided with a hard disk (HDD) that records the obtained radar waveform trace as ground radar data, measuring at each designated timing.

  The time / distance signal controller 30 generates a time pulse at a desired cycle by a square wave generated by the internal time generator 44, and generates a distance pulse by using an output pulse from the optical distance meter 20 to Control the operation timing. Furthermore, the hand marker 46 which can output a hand mark manually at arbitrary time is provided. The square wave pulse from the time generator 44 is input to the variable frequency dividers 48a and 48b, and is input to the switches 50a and 50b as time pulses of a desired period (for example, generated every 0.5 seconds). . The hand mark generated from the hand marker 46 is also input to the switching devices 50a and 50b. These switchers 50a and 50b switch between time pulses and hand marks. Then, one of the signals is input to the gates 52a and 52b. The output pulse from the optical distance meter 20 is divided by a frequency divider 54, adjusted so that, for example, a distance pulse of 1 pulse per 1 cm of moving distance is generated, and input to the underground radar device 42. The underground radar device 42 records a radar waveform at the timing of this distance pulse, and records the measurement result on the hard disk as ground radar data.

  The vehicle speed determination unit 56 determines the vehicle speed according to the time interval of the output pulse of the optical distance meter 20, and the result is a control signal for the gates 52a and 52b. For example, the gate is turned on at a speed of 300 m / h or more, and the gate is turned off at a speed of less than 300 m / h. Therefore, no time pulse is output at a speed less than 300 m / h. The time pulse (and hand mark) output from one gate 52a is input to the time code generator 34, converted into a time code (elapsed time), superimposed on a digital video image, and recorded and displayed. Further, the time pulse (and hand mark) output from the other gate 52b is input to the ground penetrating radar device 42 and recorded in the form of adding the time pulse to the ground penetrating radar data, and is input to the in-vehicle PC 32, At that timing, the cumulative distance information and GPS position information measured by the GPS device and the in-video display time are taken in, and a synchronization file is created including the cumulative number of time pulses.

  FIG. 4 shows a processing flow of the time / distance signal controller and the GPS device, and FIG. 5 shows a timing chart of the time / distance signal controller and each device. When the time / distance signal controller receives a signal from the optical distance meter and detects a vehicle speed of 300 m / h or more by the vehicle speed determination device, it starts acquiring various data. The traveling LED lights up, and the ground penetrating radar device receives a distance pulse from the optical rangefinder and, as previously set, outputs a certain number of data for each unit distance (for example, 20 radar waveform traces for every 1 meter of measurement distance). get. When the speed is less than 300 m / hour, the traveling LED is turned off and is in the HOLD state, the measurement by the ground radar device is stopped, and the recording of the synchronous file by the in-vehicle PC is also stopped. During this time, recording of the video camera video continues, and superimposition of the elapsed time in the video camera by the time code generator also continues to operate. When traveling, if there is a GPS input, the accumulated distance value and GPS position information are output, and if there is no GPS input, only the accumulated distance value is output.

A time pulse is transmitted from the time / distance signal controller at a constant time interval dt. The transmitted time pulse is recorded in the ground penetrating radar data, and the following information at the time of the time pulse transmission is stored in the in-vehicle PC as a synchronization file.
(A) Cumulative number of time pulses (b) Cumulative distance when time pulses are transmitted (c) Superimpose time (d) Time pulses captured in video camera images when time pulses are transmitted Location information by RTK-GPS at the time of transmission

  In this way, using the synchronization file recorded at the timing of the time pulse from the time / distance signal controller, the processing on the dedicated software is performed by the following procedure, and the radar waveform trace position, GPS coordinates, digital video Associate the file playback position.

FIG. 6 shows a conceptual diagram of ground penetrating radar data including time pulse information from the time / distance signal controller. The part where the time pulse interval is narrow is in the state where the vehicle speed is slow, the part where the time pulse interval is wide is in the state where the vehicle speed is fast, the part where the time pulse is equally spaced runs at a constant speed It will be in the state of doing. In the ground penetrating radar data, the cumulative number of radar waveform traces from the start of measurement and the distance data by the optical distance meter correspond one-to-one, so the radar waveform trace position at the time pulse recording position is set for each preset unit distance. It is obtained by using the number of radar waveform traces. Information recorded for system synchronization based on signals from the time / distance signal controller is as follows.
Glat (k): GPS coordinate / latitude Glon (k): GPS coordinate / longitude Galt (k): GPS coordinate / altitude D (k): Position of optical distance sensor TI (k): Super-in in video camera image Pause time

  Correspondence between an arbitrary radar waveform trace position, GPS coordinates, and superimpose time is performed according to the following procedure.

(1) The radar waveform trace position PT (k) is obtained from the ground radar data by the following method.
(1-1) Obtained from the cumulative number of time pulses in ground penetrating radar data. The radar waveform trace position PT (k) of the pulse at the (k + 1) th from the beginning is accumulated as the number of time pulses from the beginning of the ground radar data.
(1-2) From the distance meter position D (k) at the time of pulse transmission,
PT (k) = D (k) · s
s: Obtained by the number of radar waveform traces per unit distance. When there is a lack of time pulse recording in the ground penetrating radar data, an error occurs only in the above (1-1), so that the reliability of measurement can be improved by adopting two different methods.

(2) For any radar waveform trace number X∈PT (0) ≦ X ≦ PT (n−1), GPS position information at each radar waveform trace position [longitude TGlat (X), latitude TGlon (X), The altitude TGalt (X)] and the superimpose time TTI (X) are linearly interpolated using the values at the pulse positions as in the following equation.
For the interval kεPT (k) ≦ X ≦ PT (k + 1)
TGlat (X) = A1 ・ X + B1
A1 = [Glat (k + 1) −Glat (k)] / [PT (k + 1) −PT (k−1)]
B1 = [PT (k + 1) · Glat (k) −PT (k) · Glat (k + 1)] / [PT (k + 1) −PT (k)]
TGlon (X) = A2 ・ X + B2
A2 = [Glon (k + 1) -Glon (k)] / [PT (k + 1) -PT (k-1)]
B2 = [PT (k + 1) · Glon (k) −PT (k) · Glon (k + 1)] / [PT (k + 1) −PT (k)]
TGalt (X) = A3 ・ X + B3
A3 = [Galt (k + 1) −Galt (k)] / [PT (k + 1) −PT (k−1)]
B3 = [PT (k + 1) · Galt (k) −PT (k) · Galt (k + 1)] / [PT (k + 1) −PT (k)]
TTI (X) = A4 ・ X + B4
A4 = [TI (k + 1) -TI (k)] / [PT (k + 1) -PT (k-1)]
B4 = [PT (k + 1) · TI (k) −PT (k) · TI (k + 1)] / [PT (k + 1) −PT (k)]

The radar waveform trace position and the digital video file are associated with each other by acquiring a digital video reproduction position at an arbitrary radar waveform trace position according to the following procedure.
(1) The superimpose time TIs at the video playback start position is acquired from the video image.
(2) The superimpose time TIe at the video playback end position is acquired from the video image.
(3) The playback time length VL of the digital video file is acquired.
(4) From the in-video superimpose time TI (X) at an arbitrary radar waveform trace position X, the corresponding digital video playback position VT (X) is calculated using the following equation.
VT (X) = (TI (X) −TIs) · a
However, a = VL / (TIe-TIs)
The correction coefficient a is set in order to improve synchronization accuracy because the speed at which the in-video superimposition time advances and the video playback speed may be slightly different.

  In the measurement of ground penetrating radar that travels on the road surface in this way, by creating a synchronization file and using ground penetrating radar data incorporating a time pulse, the measured ground penetrating radar data and position information and acquisition by GPS It is possible to accurately link the digital video image of the position, and easily extract information on an arbitrary place with respect to underground structures such as cavities under the road, buried objects, and structures.

14 Video Camera 16 GPS Device 18 Car Navigation 20 Optical Distance Meter 22 Antenna 30 Time / Distance Signal Controller 32 Car PC
34 Time code generator 36 Multi viewer 38 Liquid crystal display 42 Ground penetrating radar device 44 Time generator

Claims (4)

In-vehicle ground penetrating radar measuring device that is equipped with a ground penetrating radar device, a distance meter, a plurality of digital video cameras, a time code generator that captures the elapsed time of measurement in a digital video image, and a GPS device, and that searches under the road surface while traveling A system synchronization method for linking measured ground penetrating radar data with GPS position information and digital video images,
Using a time / distance signal controller that generates a distance pulse based on a reference time pulse and a distance meter, the ground radar device receives the distance pulse and records a certain number of radar waveforms for each unit distance during travel. The time pulse is recorded as ground radar data, and for each time pulse, (a) the cumulative number of time pulses, (b) the accumulated distance traveled, and (c) the super code of the time code generator. A synchronization file in which the pause time and (d) GPS coordinates are recorded is generated, and the radar waveform trace position of the ground radar data is associated with the GPS coordinates of the synchronization file and the superimpose time using the time pulse as a medium. A system synchronization method for an in-vehicle ground penetrating radar measuring apparatus, characterized in that it is configured as described above. The radar waveform trace position at the time of arbitrary time pulse transmission sent from the time / distance signal controller
(1) The system synchronization method for an onboard ground penetrating radar measurement apparatus according to claim 1, wherein the system synchronization method is obtained from both the cumulative number of time pulses of ground radar data (2) the cumulative distance at the time pulse transmission recorded in the synchronization file.   3. The system synchronization method for an on-vehicle ground penetrating radar measurement apparatus according to claim 2, wherein the GPS coordinates and the superimpose time at an arbitrary radar waveform trace position are obtained by linear interpolation using the radar waveform trace position of the time pulse.   Using the correction coefficient obtained by dividing the actual video playback time length by the superimpose time length in the video, the video playback position at any radar waveform trace position is corrected and calculated. 4. The system synchronization method for an in-vehicle ground penetrating radar measuring apparatus according to claim 3, wherein the digital video image is supported.

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