JP5936411B2 - Displacement detection method and displacement detection apparatus at GPS observation point - Google Patents

Description

The present invention relates to a displacement detection method and a displacement detection apparatus at a GPS observation point.

  In recent years, various measurements using a global positioning system (hereinafter referred to as GPS), for example, a three-dimensional position on the earth, a change in the crust, and a displacement amount of the sea surface are measured. In the measurement using the GPS, the positioning is disturbed depending on the reception environment of the signal from the GPS satellite. For this reason, even if the positioning data fluctuates, it is difficult to determine in real time whether the measurement point is actually displaced or whether it is due to positioning disturbance.

  In particular, when measuring crustal movements, GPS observation points are often installed between mountains, and the influence of multipath from mountain slopes and trees is usually large in mountains, and positioning data is frequently disturbed. To do.

  A GPS positioning device using a Kalman filter has been proposed as a means for removing such disturbance, that is, an error (see, for example, Patent Document 1).

JP 2005-221374 A

  However, the invention described in Patent Document 1 has a problem that the occurrence of displacement cannot be detected in real time because a time delay occurs in removing errors by using the Kalman filter. On the other hand, if positioning data that does not remove errors is used for displacement detection, displacement may be erroneously detected when affected by multipath or the like.

  Accordingly, the present invention provides a displacement detection method and a displacement detection apparatus that can accurately detect a displacement that has actually occurred in real time without detecting it as a displacement even if positioning data fluctuates due to the influence of a multipath or the like. The purpose is to provide.

In order to solve the above problem, the displacement detection method of the present invention according to claim 1 is a method of detecting the displacement of the ground at a GPS observation point,
An error removal step for removing an error for each stellar day from the positioning data obtained in real time at the GPS observation point, without performing processing that causes a time delay;
A data storage step for storing positioning data from which errors have been removed in this error removal step;
A reference value calculating step for calculating a reference value serving as a reference of the positioning data from which the error is removed;
A deviation calculating step for calculating a deviation of the positioning data from which the current error is removed with the reference value as a reference;
An allowable range calculation step of calculating a standard deviation from the positioning data at a predetermined time stored in the data storage step and multiplying the standard deviation by a predetermined coefficient to obtain an allowable range of the deviation;
A first determination step of determining whether the current deviation is outside the allowable range;
A determination result storage step for storing the result determined in the first determination step;
A second determination step of detecting as a displacement if the ratio at which the deviation is determined to be out of the permissible range is greater than or equal to a predetermined value among the above results at other predetermined times stored in the determination result storage step; ,
A reference value update step of correcting the reference value to a value approaching the subsequent positioning data when detected as a displacement in the second determination step.

A displacement detection method according to a second aspect of the present invention is the displacement detection method according to the first aspect of the present invention, wherein a lower limit value is set in an allowable range.
Furthermore, the displacement detection device of the present invention according to claim 3 is a device for detecting the displacement of the ground at the GPS observation point,
An error removing unit that removes an error for each stellar day without performing processing that causes a time delay from positioning data obtained in real time at a GPS observation point;
A data storage unit for storing positioning data from which errors have been removed by the error removal unit;
A reference value calculation unit for calculating a reference value serving as a reference of the positioning data from which the error is removed;
A deviation calculating unit that calculates the deviation of the positioning data from which the current error has been removed with the reference value as a reference;
A standard deviation is calculated from the positioning data stored in the data storage unit at a predetermined time to the present time, and an allowable range calculation unit that multiplies the standard deviation by a predetermined coefficient to set the allowable range of the deviation;
A first determination unit for determining whether the current deviation is outside the allowable range;
A determination result storage unit for storing the result determined by the first determination unit;
A second determination unit that detects a displacement if the ratio at which the deviation is determined to be outside the allowable range is greater than or equal to a predetermined value among the above results at other predetermined times stored to the present time stored in the determination result storage unit;
And a reference value update unit that corrects the reference value to a value approaching the subsequent positioning data when the second determination unit detects the displacement.

  A displacement detection device according to a fourth aspect of the present invention is the displacement detection device according to the third aspect of the present invention, wherein a lower limit is set in an allowable range.

  According to the displacement detection method and the displacement detection apparatus, even if the positioning data fluctuates due to the influence of multipath or the like, it is not detected as a displacement, and the actually generated displacement can be detected accurately and in real time.

1 is a schematic configuration diagram of a ground observation system to which a displacement detection device according to an embodiment of the present invention is applied. It is a block diagram of the displacement detection apparatus. It is a schematic diagram which shows the judgment by the 1st judgment part and the 2nd judgment part in the displacement detection apparatus, (a) shows the judgment by a 1st judgment part, (b) shows the judgment by a 2nd judgment part. In the time-series graph of data at the time of occurrence of displacement calculated by the displacement detection device, (a) shows positioning data and reference values, and (b) shows deviation and allowable range. In the time series graph of data when no displacement occurs (with influence of multipath or the like) calculated by the displacement detection device, (a) shows positioning data and reference values, and (b) shows deviation and allowable range. FIG. 6 is a time-series graph of data at the time of occurrence of displacement calculated by the displacement detection device according to the embodiment of the present invention, in which (a) shows positioning data and reference values, (b) shows deviations and allowable ranges, (c) Indicates a ratio and a predetermined value. In the time series graph of data when no displacement occurs (with influence of multipath, etc.) calculated by the displacement detection device, (a) shows positioning data and reference values, (b) shows deviations and allowable ranges, (C) shows a ratio and a predetermined value.

Hereinafter, a displacement detection method and a displacement detection apparatus for a GPS observation point according to an embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, a case where the GPS observation point displacement detection method and the displacement detection device according to the present invention are applied to a ground observation system using GPS will be described.

In the ground observation system according to the present embodiment, positioning data of the ground is obtained using a real-time kinematic method (hereinafter referred to as RTK method).
The RTK method will be briefly described. This is a relative positioning method using data from a reference station whose position is known, and more specifically, a dynamic interference positioning method.

  This RTK method can perform highly accurate measurement by measuring the phase of a carrier wave from a GPS satellite, but it is necessary to determine an integer value bias corresponding to an integer wavelength in interference positioning, for example, 5 It is determined by applying the least square method to the positioning data from the above GPS satellites.

In this way, the measurement position when the integer value bias is determined is called a fixed solution (also called the integer value fixed state where the integer value bias is fixed), and the measurement position when the integer value bias cannot be determined is floated. This is called a solution (also called an integer value non-deterministic state where the integer value bias is not fixed). That is, in this RTK method, the positioning accuracy is corrected by using a fixed solution (accuracy of about several centimeters), a float solution (accuracy of about several centimeters to several tens of centimeters), and data from a reference station. A DGPS solution (accuracy of about several meters, precisely called a code DGPS solution), a single positioning solution based on single positioning (accuracy of about several tens of meters), and a positioning operation incapable of obtaining a solution In general, an RTK-type GPS receiver has a function of outputting positioning accuracy data (also referred to as accuracy status) for informing the current positioning accuracy.

  Then, in the ground observation system according to the present embodiment, if the positioning accuracy data is the fixed solution, the positioning data is analyzed in real time to detect whether or not the GPS observation point is displaced.

First, a schematic configuration of a ground observation system including a displacement detection device that detects a displacement of a GPS observation point will be described with reference to FIG.
As shown in FIG. 1, the ground observation system 1 includes a GPS observation point 2 installed at a point where the displacement of the ground such as a mountain can be measured and a position (for example, 10 km from the GPS observation point 2) that can cancel the GPS observation error. Positioning analysis that calculates the GPS reference point 3 installed in the range) and the GPS observation point 2 and the data from the GPS reference point 3 and calculates the positioning data (three-dimensional coordinate data) at the GPS observation point 2 by the RTK method The device 4, a displacement detection device 5 that can detect the displacement of the GPS observation point 2 based on the positioning data from the positioning analysis device 4, and the displacement of the GPS observation point 2 detected by the displacement detection device 5 are displayed. And a monitoring device (for example, a monitor for a personal computer) 6.

  The GPS observation point 2 and the GPS reference point 3 are provided with a GPS antenna at the top for receiving signals from GPS satellites, a communication device for communicating with other measurement units, and other necessary devices. Is provided inside.

Next, the displacement detector 5 which is the gist of the present invention will be described in detail with reference to FIG.
As shown in FIG. 2, the displacement detection device 5 inputs the positioning data at the GPS observation point 2 from the positioning analysis device 4 in real time and stores the positioning data in time series, and the input An error removing unit 12 that removes the error for each stellar day in real time without performing processing that causes time delay from the positioning data input and stored in the storage unit 11, and the positioning data from which the error is removed by the error removing unit 12 The data sorting unit 13 that sorts the fixed solution positioning data from the data in real time, the data storage unit 14 that stores the fixed solution positioning data sorted by the data sorting unit 13 in time series, and the data storage unit 14 stores the data. A reference value calculation unit 15 that calculates a reference value from a large number of positioning data, and the positioning data of the data selection unit 13 based on the reference value And a deviation calculating section 16 for calculating a difference in real time.

  The displacement detection device 5 calculates the standard deviation in real time from a large number of positioning data stored in the data storage unit 14 for a predetermined time, and multiplies the standard deviation by a predetermined coefficient in real time to determine the allowable range of the deviation. An allowable range calculation unit 17 for calculating the deviation, a first determination unit 18 for determining in real time whether the deviation calculated by the deviation calculation unit 16 is outside the allowable range calculated by the allowable range calculation unit 17, and the first The determination result storage unit 19 that stores the determination results by the determination unit 18 in time series, and the deviation among the above results at other predetermined times stored in the determination result storage unit 19 is determined to be out of the allowable range. A second determination unit 20 that detects a displacement if the ratio is equal to or greater than a predetermined value, and a reference value that is used by the deviation calculation unit 16 when the second determination unit 20 detects the displacement. A reference value updating section 21 that updates the Tana reference value, and an output unit 22 which outputs a notification that is detected as a displacement in the second determination unit 20 to the monitoring device 6. The predetermined coefficient is determined by iterative calculation using data for the past one week, for example, as a value that does not cause erroneous detection.

  The error removing unit 12 uses the fact that GPS satellites are arranged in the same manner for each star day, and subtracts the positioning data one star day before stored in the input storage unit 11 from the current positioning data. It eliminates errors for each stellar day in real time. Further, every time the second determination unit 20 detects the displacement, the reference value update unit 21 reads a predetermined number of positioning data immediately before being detected as the displacement from the data storage unit 14, and these read positionings. A new reference value is calculated from the data, and the reference value used in the deviation calculating unit 16 is updated to the new reference value.

Hereinafter, a displacement detection method using the displacement detection device 5 will be described with reference to FIGS.
As shown in FIG. 1, the GPS observation point 2 and the GPS reference point 3 always receive signals from GPS satellites and transmit data for calculating positioning data to the positioning analysis device 4. The positioning analysis device 4 analyzes the data from the GPS observation point 2 and the GPS reference point 3 to calculate the positioning data of the GPS observation point 2 by the RTK method, and transmits this positioning data to the displacement detection device 5.

  As shown in FIG. 2, in the displacement detection device 5, the positioning data is input to the input storage unit 11 in real time, and the positioning data is stored in time series, and then the error removal unit 12 delays the time from the positioning data. The error for each stellar day is removed in real time without performing the process of generating (error removal step). Then, the positioning data of the fixed solution is selected in real time from the positioning data from which the error for each fixed star day has been removed, and the positioning data of the selected fixed solution is stored in the data storage unit 14 in time series ( Data storage step). Thereafter, the reference value calculation unit 15 calculates a reference value from a large number of positioning data stored in the data storage unit 14 (reference value calculation step). Further, the deviation calculation unit 16 calculates the deviation of the positioning data of the data selection unit 13 based on the reference value in real time (deviation calculation step).

  Then, the tolerance calculation unit 17 calculates the standard deviation in real time from a large number of positioning data stored in the data storage unit 14 in a predetermined time, and multiplies the standard deviation by a predetermined coefficient to calculate the tolerance in real time. (Allowable range calculation step). Then, the first determination unit 18 determines in real time whether the deviation calculated by the deviation calculation unit 16 is outside the allowable range calculated by the allowable range calculation unit 17 [first determination step, FIG. reference]. The determination result by the first determination unit 18 is stored in the determination result storage unit 19 in time series (determination result storage step). Thereafter, if the ratio at which the deviation is determined to be outside the allowable range among the results at other predetermined times stored in the determination result storage unit 19 is equal to or greater than the predetermined value, the second determination unit 20 detects the displacement. [Second determination step, see FIG. 3B]. When the second determination unit 20 detects the displacement, the reference value update unit 21 updates the reference value used by the deviation calculation unit 16 to a new reference value (reference value update step). On the other hand, the output unit 22 outputs to the monitoring device 6 that the second determination unit 20 detects the displacement.

Hereinafter, how the displacement is detected by the displacement detection device 5 will be described with reference to time-series graphs of positioning data shown in FIGS. 4 and 5.
First, the case where displacement actually occurs at the GPS observation point 2 will be described with reference to FIG.

  As shown in FIG. 4A, the positioning data when the displacement actually occurs changes rapidly at a certain time t2, but the time t1 before the change and the times t3 to t5 after the change are substantially constant. . In other words, the time series graph of the positioning data has a shape having a significant step. This step is due to the displacement that actually occurs.

  More specifically, as shown in FIG. 4A, the positioning data is substantially constant at time t1, although there is some variation. Naturally, as shown in FIG. 4B, the deviation, which is a value obtained by subtracting the reference value from the positioning data, is also substantially constant near the horizontal axis (0 point) at time t1. And the positioning data shown to Fig.4 (a) is fluctuate | varied rapidly at the time t2, and the deviation shown to FIG.4 (b) also fluctuates abruptly similarly. Since the standard deviation increases as the positioning data fluctuates, as shown in FIG. 4B, the allowable range that is a value obtained by multiplying the standard deviation by a predetermined coefficient also rapidly increases at time t2. Thereafter, the positioning data shown in FIG. 4 (a) becomes substantially constant at time t3, and the deviation shown in FIG. 4 (b) also becomes substantially constant. For this reason, since the standard deviation of positioning data decreases rapidly at time t3, the allowable range shown in FIG. 4B also decreases rapidly. Then, as shown in FIG. 4B, the deviation falls outside the allowable range at the first time point of time t4. In addition, if the ratio at which the deviation is determined to be outside the allowable range among the results of the first determination unit 18 at another predetermined time at the last time point of time t4 is 50% (an example of a predetermined value) or more, While detecting the occurrence of displacement, the reference value is updated as shown in FIG. As a result, the reference value shown in FIG. 4A again approaches the substantially constant positioning data at the first time point of time t5, so that the deviation shown in FIG. 4B also approaches the horizontal axis (0 point). It becomes almost constant. For this reason, as shown in FIG. 4B, at time t5, the deviation is within the allowable range, and no displacement is detected unless a new displacement occurs. Therefore, when a displacement actually occurs, the displacement detector 5 detects the occurrence of the displacement in real time.

Next, a case where the GPS observation point 2 is affected by multipath or the like but does not generate displacement will be described with reference to FIG.
As shown in FIG. 5A, the positioning data in this case fluctuates at a certain time t′2 to t′4, but the first half of the time t′2 to t′3 and the second half of the time t′3 to t′4. Thus, the direction of change is reversed, and the time t′1 before the change and the time t′5 after the change become substantially constant. In other words, the time series graph of the positioning data has a shape having valleys (or peaks). This valley (or mountain) is due to the influence of multipath or the like.

  More specifically, as shown in FIG. 5A, the positioning data is substantially constant at time t′1, although there is some variation. Naturally, as shown in FIG. 5B, the deviation, which is a value obtained by subtracting the reference value from the positioning data, is also substantially constant near the horizontal axis (0 point) at time t′1. The positioning data shown in FIG. 5A varies at time t′2, and the deviation shown in FIG. 5B also varies in the same manner. Since the standard deviation increases as the positioning data fluctuates, as shown in FIG. 5B, an allowable range that is a value obtained by multiplying the standard deviation by a predetermined coefficient also increases at time t'2. Thereafter, the positioning data shown in FIG. 5A becomes a peak at time t'3, and the fluctuation direction is reversed. Therefore, the deviation shown in FIG. 5B is the same. When the positioning data becomes a peak and the fluctuation direction is reversed, the standard deviation of the positioning data is reduced, so that the allowable range shown in FIG. 5B is also reduced. Then, as shown in FIG. 5B, the deviation falls outside the allowable range at time t'3. However, since the positioning data continues to fluctuate while the fluctuation direction is reversed at time t'4, the standard deviation of the positioning data increases again, and the allowable range also increases. For this reason, before the ratio at which the deviation is determined to be out of the allowable range among the results of the first determination unit 18 at another predetermined time at time t′4 is 50% or more (which is an example of a predetermined value), Deviation is within tolerance. At time t′5, since the positioning data is substantially constant near the reference value, the deviation is substantially constant near the horizontal axis (0 point), so that the deviation is allowed as shown in FIG. Maintained within range. Even when the positioning data is stable and the standard deviation becomes extremely small at times t′1 and t′5, the lower limit value is set in the allowable range, so even if the positioning data slightly varies, it is out of the allowable range. The displacement is not detected by mistake. Therefore, when no displacement actually occurs, even if the positioning data fluctuates due to the influence of multipath or the like, the displacement detection device 5 does not detect the occurrence of the displacement.

  Hereinafter, the displacement detection device 5 and the displacement detection method according to the embodiment of the present invention will be described based on more specific examples.

  In the displacement detection device 5 and the displacement detection method according to the present embodiment, the measurement frequency of the positioning data is set to once per second, and the predetermined time for calculating the standard deviation of the positioning data is 360 seconds (360 positioning data is a parameter). The predetermined coefficient is 1.2, and another predetermined time for detecting the occurrence of displacement by the second determination unit 20 is 360 seconds (the result of 360 determinations by the first determination unit 18 is the second). The lower limit of the allowable range is 1 mm.

  FIG. 6 shows a time-series graph when a displacement of 10 mm actually occurs under these conditions. Further, FIG. 7 shows a time series graph in the case where no displacement occurs although the positioning data fluctuates about 10 mm in 15 minutes under the above conditions.

  When a displacement of 10 mm actually occurred, as shown in FIG. 6A, a step was observed around 13:01 in the time series graph of the positioning data. Further, as shown in FIG. 6 (b), the deviation continues to be outside the allowable range from around 13:07, and as shown in FIG. 6 (c), the deviation of the result of the first determination unit 18 in 360 seconds is The percentage judged to be out of tolerance began to increase. And this ratio became 50% or more around 13:14, and the occurrence of displacement was detected.

  If the positioning data fluctuates about 10 mm in 15 minutes as disturbance, but no displacement occurs, as shown in FIG. 7A, the time series graph of the positioning data is around 10:45 to 11:02. A mountain was seen. Further, as shown in FIG. 7 (b), the deviation continues to be outside the allowable range from about 10:51, and as shown in FIG. 7 (c), the deviation of the result of the first determination unit 18 in 360 seconds is The percentage judged to be out of tolerance began to increase. However, as shown in FIG. 7 (b), the deviation is within the allowable range from around 11:02, and as shown in FIG. 7 (c), the above ratio starts to decrease and does not reach 50%. The occurrence of was not detected.

  As described above, according to the displacement detection device 5 and the displacement detection method according to the above-described embodiments and examples, even if the positioning data fluctuates due to the influence of multipath or the like, it is not detected as displacement, and actual displacement occurs Can be detected accurately and in real time.

  Further, according to the displacement detection device 5 and the displacement detection method according to the above-described embodiment and examples, it is possible to detect the occurrence of the displacement of the GPS observation point 2 in real time without causing a time delay.

  By the way, in the said embodiment and Example, although what was applied to the ground observation system 1 was demonstrated, it is not limited to this, Even if it is applied to other systems, such as a sea level observation system Good.

  In the above-described embodiments and examples, the positioning data is calculated by the RTK method. However, the present invention is not limited to this, and other methods such as a single positioning method and a DGPS method may be used.

DESCRIPTION OF SYMBOLS 1 Ground observation system 2 GPS observation point 3 GPS reference point 5 Displacement detection apparatus 12 Error removal part 13 Data selection part 15 Reference value calculation part 16 Deviation calculation part 17 Allowable range calculation part 18 First judgment part 19 Judgment result storage part 20 Second judgment part 21 Reference value update part

Claims (4)

A method for detecting ground displacement at a GPS observation point,
An error removal step for removing an error for each stellar day from the positioning data obtained in real time at the GPS observation point, without performing processing that causes a time delay;
A data storage step for storing positioning data from which errors have been removed in this error removal step;
A reference value calculating step for calculating a reference value serving as a reference of the positioning data from which the error is removed;
A deviation calculating step for calculating a deviation of the positioning data from which the current error is removed with the reference value as a reference;
An allowable range calculation step of calculating a standard deviation from the positioning data at a predetermined time stored in the data storage step and multiplying the standard deviation by a predetermined coefficient to obtain an allowable range of the deviation;
A first determination step of determining whether the current deviation is outside the allowable range;
A determination result storage step for storing the result determined in the first determination step;
A second determination step of detecting as a displacement if the ratio at which the deviation is determined to be out of the permissible range is greater than or equal to a predetermined value among the above results at other predetermined times stored up to the present time stored in the determination result storage step; ,
A displacement detection method at a GPS observation point, comprising: a reference value update step of correcting the reference value to a value approaching positioning data thereafter when detected as a displacement in the second determination step.   2. The displacement detection method at a GPS observation point according to claim 1, wherein a lower limit value is set in the allowable range. A device for detecting ground displacement at a GPS observation point,
An error removing unit that removes an error for each stellar day without performing processing that causes a time delay from positioning data obtained in real time at a GPS observation point;
A data storage unit for storing positioning data from which errors have been removed by the error removal unit;
A reference value calculation unit for calculating a reference value serving as a reference of the positioning data from which the error is removed;
A deviation calculating unit that calculates the deviation of the positioning data from which the current error has been removed with the reference value as a reference;
A standard deviation is calculated from the positioning data stored in the data storage unit at a predetermined time to the present time, and an allowable range calculation unit that multiplies the standard deviation by a predetermined coefficient to set the allowable range of the deviation;
A first determination unit for determining whether the current deviation is outside the allowable range;
A determination result storage unit for storing the result determined by the first determination unit;
A second determination unit that detects a displacement if the ratio at which the deviation is determined to be outside the allowable range is greater than or equal to a predetermined value among the above results at other predetermined times stored to the present time stored in the determination result storage unit;
A displacement detection device at a GPS observation point, comprising: a reference value update unit that corrects the reference value to a value approaching the subsequent positioning data when the second determination unit detects the displacement.   The displacement detection device at a GPS observation point according to claim 3, wherein a lower limit value is set in the allowable range.

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