JP2009288142A - Method for estimating correction value prediction formula, method for calculating correction value for specifying location, program for estimating correction value prediction formula, and program for calculating correction value for specifying location - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable specifying location with high degree of accuracy without using an enormous amount of correction values. <P>SOLUTION: A mobile station independently performs positioning (S1) and sends a rough position to a reference station (S2). The closest reference station is selected and chooses a correction value prediction formula (S3) and sends a coefficient for the prediction formula or the correction value prediction formula. The mobile station uses the sent coefficient for the prediction formula or the correction value prediction formula to perform positioning calculation (S6). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a correction value prediction formula estimation method, a position specification correction value calculation method, a correction value prediction formula estimation program, and a position specification correction value calculation program that make it possible to specify a position with high accuracy.

  As this type of technology, for example, a differential GPS (DGPS) positioning technology developed to identify the position of a device with high accuracy has been developed. This DGPS positioning technique measures the distance to the satellite at a fixedly fixed reference station and uses the error between the measured distance and the true distance as a correction value to improve the accuracy. It is a technique. In normal GPS, an error of about 10 to 100 m occurs, but if the DGPS positioning technology is applied, it can be suppressed to less than this error.

Since the correction value used in this case changes with the passage of time, it is necessary to always use the latest correction value. Therefore, the accuracy deteriorates unless communication is frequently performed with the mobile body to obtain the latest correction value and position correction. Therefore, a positioning method is considered in which accuracy is maintained by predicting current or future correction values from the latest past correction values (see, for example, Patent Document 1). A positioning method using correction values at the same time in the past is also considered (see, for example, Patent Document 2).
JP 2004-069587 A JP-A-11-109018

  However, even if the technical idea of Patent Document 1 is applied, since the most recent past correction value data stored in the receiver itself is used, it is possible to predict only for the future several tens of minutes and for a long time. The available time of the prediction formula is short. In addition, for example, the correction value when DGPS positioning is applied differs for each reference point (reference station), so it is necessary to select the reference point closest to the current position, but when the moving body moves, the nearest reference point Changes, the past correction values cannot be used and cannot be predicted. Therefore, it is not suitable for positioning with a moving body. Further, according to the technical idea of Patent Document 2, correction value data at the same time in the past must be held.

  The present invention has been made in view of the above circumstances, and its purpose is to provide a correction value prediction formula estimation method and a position specification correction value calculation method that enable high-accuracy position specification without using a huge amount of correction values. Another object of the present invention is to provide a correction value prediction formula estimation program and a position specifying correction value calculation program.

  According to the first or ninth aspect of the invention, since a correction value prediction formula that can calculate a correction value at a predetermined time point in the present or the future can be estimated based on a correction value prediction formula that has been approximately predicted in advance, The position can be specified with high accuracy without using a value.

According to the second aspect of the present invention, since the estimation is performed by selecting from the correction value prediction expressions stored in the storage unit in advance, the correction value prediction expression can be quickly determined.
According to the invention of claim 3, the correction value prediction formula can be set by performing the time offset, the correction value offset, the rotation offset of the time and the correction value, or the enlargement / reduction offset process. Be able to comply with the law.

  According to the invention of claim 4, the correction value prediction formula using the correction value group closer to today is used to estimate the correction value prediction formula based on the correction value prediction formula approximated from the correction value group of the previous day. The correction value prediction formula can be estimated based on the above, a more practical correction value prediction formula can be estimated, and the position can be specified with high accuracy.

  According to the fifth aspect of the present invention, the correction value prediction formula is estimated based on the correction value prediction formula using the correction value group closer to the situation in order to estimate the correction value prediction formula based on weather conditions such as ionosphere and weather. And a more practical correction value prediction formula can be estimated, and the position can be specified with high accuracy.

According to the sixth aspect of the present invention, the reference station side distributes the information on the mode of the correction value prediction formula or the information on the coefficient of the correction value prediction formula to the mobile station side, so the data communication amount can be reduced.
As in the invention according to claim 7 or 10, the position specifying correction value at a predetermined time may be calculated from the correction value prediction formula. According to the invention according to claim 8, the estimation process of the correction value prediction formula estimation method according to any one of claims 1 to 6 is executed on the reference station side, and the calculation process is executed on the mobile station side. Therefore, the load can be distributed and processed at a high speed.

Hereinafter, an embodiment in which the present invention is applied to a differential GPS (hereinafter abbreviated as DGPS) position specifying process will be described with reference to the drawings.
FIG. 1 schematically shows the mechanism of the DGPS system according to the present embodiment. The DGPS method is a method of correcting a position specifying error of a mobile station receiver using a positioning error in a reference station receiver whose position is known, and within a certain predetermined range close to a reference point (reference station), GPS is used. Utilizing the property that the positioning errors of are almost the same. As shown in FIG. 1, a reference station 1 is installed as a reference point at a fixed position. The reference station 1 is installed at a point where an accurate position is known in advance and is equipped with a receiver, and receives GPS signals from a plurality of GPS satellites 2 (2a, 2b...).

  When the distance from the GPS satellite 2 is measured based on the GPS signal received by the reference station 1, the pseudo distance to the virtual reference station 1a can be measured. The true distance calculated based on the exact position of the reference station 1 The positioning error can be accurately obtained by comparing the pseudo distance.

  In a certain range from the point where the reference station 1 is installed, the positioning error becomes almost the same value. The reference station 1 calculates a correction value prediction formula and its coefficient or correction value based on the positioning error obtained by the reference station 1. At this time, the positioning error differs for each of the plurality of GPS satellites 2 (2a, 2b...), And also depends on the ionosphere and troposphere conditions. Therefore, at this time, for example, every several hours, every day, etc. It is required to calculate the correction value prediction formula calculated or the correction value at a predetermined time point derived from the correction value prediction formula with high accuracy.

  When the reference station 1 obtains the correction value prediction formula or the correction value, it transmits it to the mobile station 3. The mobile station (positioning device) 3 can measure the pseudo distance between the GPS satellite 2 and the virtual mobile station 3a by measuring alone based on the GPS signal, but the correction value prediction formula or correction value received from the reference station 1 The position can be identified with high accuracy by correcting the position error using.

  That is, the correction value indicates the difference between the pseudo distance in the reference station 1 (observed value of the distance between the GPS satellite 2 and the reference station (reference point) 1) and the true distance, and the correction value is used. The position is specified by correcting the position error on the mobile station 3 side.

This will be specifically described below. In the present embodiment, the following system is applied.
FIG. 2 schematically shows the electrical configuration of the reference station and the mobile station using a block diagram. As shown in FIG. 2, the reference station 1 includes a server having a CPU, a memory, and the like, and achieves each function shown in FIG. 2 by the hardware and software of the server. Functionally, the reference station 1 includes a correction value prediction formula selection unit 4, a correction value prediction formula offset unit 5, a correction value prediction formula database 6 as a storage unit, and a data transmission / reception unit 7. The data transmission / reception unit 7 includes a correction value information distribution unit 8 and a mobile station information reception unit 9.

  The correction value prediction formula database 6 stores a large number of correction value prediction formulas approximated in advance based on correction value groups measured in the past, together with accurate position information of the reference station 1. Note that a plurality of reference stations 1 (for example, about 1200) are installed throughout the country, and a correction value prediction formula is stored in the database 6 for each reference station 1 at the plurality of locations, for example, only correction value groups in the whole country.

  Since the correction value changes every day depending on weather conditions such as ionosphere and weather, when the correction value is acquired continuously in time, the correction value becomes different every day. The correction value prediction formula is configured by defining a correction value group acquired continuously for one period in the past (for example, one day, half day, several hours) by an approximation formula. The database 6 stores the approximate expression for one cycle for a predetermined period (for example, 1 year, 10 years, and several decades) that goes back from the present to the past.

  The correction value prediction formula is stored in the form of a formula (for example, a polynomial (secondary formula, cubic formula, etc.), logarithmic function, exponential function,...) Based on a prediction formula taking into account various error factors related to position detection by GPS. Has been. Since the form of these expressions only needs to indicate the form information of the expression and the coefficient information constituting the expression, the amount of information can be suppressed as much as possible. Therefore, the amount of stored data can be reduced as much as possible compared to storing correction value data measured and calculated in the past as it is.

  The correction value prediction formula selection unit 4 is considered appropriate by appropriately selecting the correction value prediction formula stored in the correction value prediction formula database 6 from the approximate position information received from the mobile station 3 through the mobile station information reception unit 9. A correction value prediction formula is estimated.

  For example, when estimating the correction value prediction formula for one day (one cycle) of today, the correction value prediction formula for the first day of the previous day that is predicted to be close to the correction value is selected and applied. Good to do. That is, since the correction value determined for each reference station 1 changes every day, it is difficult to apply the correction value before a predetermined period (for example, one week to two weeks). Further, a correction value prediction formula may be selected and applied based on weather conditions such as ionosphere and weather. That is, if the weather conditions such as the ionosphere and the weather are the same, the changing tendency of the correction value is also the same.

  The correction value prediction formula offset unit 5 offsets the correction value prediction formula selected by the correction value prediction formula selection unit 4 and distributes it through the correction value information distribution unit 8. The information distributed at this time is a mode of the correction value prediction formula after the processing is performed and a coefficient of the correction value prediction formula.

  Here, the aspect of the correction value prediction formula indicates the above-described “formal form”. This mode indicates a polynomial, a logarithmic function, an exponential function,. Further, the coefficient of the correction value prediction formula indicates the “coefficient in the form of the formula”. That is, in the case of a polynomial, it is a coefficient of a 0th-order term, a first-order term, and a second-order term. The correction value prediction formula is an approximation formula that varies from day to day, but if it is determined that the correction value prediction formula is effective within a certain time range where there is little change due to the influence of weather conditions such as the ionosphere and the weather, etc. In some cases, it is possible to determine that the change of the correction value prediction formula is valid by changing only the “coefficient” without changing the “mode” of the correction value prediction formula. In this case, only the coefficient of the prediction formula is distributed.

  On the other hand, the mobile station (positioning device) 3 includes a microcomputer having a CPU, a memory, and the like, and achieves each function illustrated in FIG. 2 by the hardware and software of the microcomputer.

  Functionally, the mobile station 3 includes a GPS signal receiving unit 10, a pseudo distance correcting unit 11, a positioning unit 12, and a data transmitting / receiving unit 13. The data transmission / reception unit 13 includes an approximate position distribution unit 14 and a correction value information reception unit 15. The GPS signal receiving unit 10 receives GPS signals from the GPS satellites 2 (2a, 2b...). The positioning unit 12 detects the approximate position based on the GPS signal. The approximate position distribution unit 14 transmits the approximate position to the reference station 1. The correction value information receiving unit 15 receives a correction value prediction formula distributed from the reference station 1 or a coefficient for the correction value prediction formula.

The operation of the above configuration will be described. FIG. 3 schematically shows a communication sequence diagram between the reference station and the mobile station applied while the correction value prediction formula is recognized to be valid.
As shown in FIG. 3, on the mobile station 1 side, the positioning unit 12 performs independent positioning based on the GPS signal received by the GPS signal receiving unit 10 (S1), thereby detecting the approximate position and detecting the approximate position. Is transmitted as a packet through the approximate position distribution unit 14 (S2). FIG. 4A schematically shows the content of information transmitted from the mobile station to the reference station. As shown in FIG. 4, information transmitted from the mobile station 3 to the reference station 1 is latitude information and longitude information.

  As shown in FIG. 3, upon receiving the approximate position of the mobile station 3, the reference station 1 side selects a reference point (reference station 1) that is closest to the mobile station 3, and selects the correction value prediction formula for the selected reference station 1 A coefficient is selected (S3). Next, on the reference station 1 side, the correction value prediction equation offset unit 5 offsets the correction value prediction equation so as to meet the conditions at the time of positioning (S4). Then, the coefficient of the correction value prediction formula (if necessary, the correction value prediction formula) is transmitted (S5).

  Thereafter, for example, when it is determined that the ephemeris (orbit information from the GPS satellite) is changed or the coefficient of the correction value prediction formula cannot be applied by traveling for a certain time or a certain distance, the process returns to step S1. Repeat again. This is because when the ephemeris (orbit information from the GPS satellite) is switched, the tendency of the correction value change may change, and the correction value prediction formula is estimated again by capturing the tendency of the change.

  FIG. 4B shows the contents of data (packets) transmitted from the reference station to the mobile station. As shown in FIG. 4B, the data contents include latitude information, longitude information, prediction formula generation time information, satellite number information (satellite identification number information), and visible satellites at the reference point (reference station 1). Several minutes of prediction formula coefficient information is included. Since the prediction formula coefficient information is determined for each satellite, it is added and transmitted immediately after the satellite number information of each satellite.

  In this way, the correction value at the predetermined time point in the present or future can be used on the mobile station 3 side, and the DGPS positioning calculation can be accurately performed by applying the correction value prediction formula in step S6.

5 to 8 schematically show an example of the offset method implemented in step S4 of FIG. For example, when the correction value approximation formula is set in a daily cycle, the correction value prediction formula F2 (t) for the current day is determined using the approximation formula F1 (t) of the previous day, which approximates the correction value of the previous day by time. Consider the case. As shown in FIGS. 5 to 7, for example, a case will be described where a quadratic polynomial is assumed by the approximate expression F1 (t) = ax ² + bx + c. Note that this approximate expression F1 (t) is assumed for easy understanding of the explanation, and is different from the description in the drawing.

  FIG. 5 shows an example in which the time axis is offset by translating the approximate expression F1 (t) along the time axis. In this case, a predetermined offset point (predetermined time) τ-Pt is set in order to match F1 (t) with today's time zone, and the correction value overlaps by adding the Pt time to the offset point τ-Pt. Perform time offset by aligning the axes.

FIG. 6 shows an example in which the correction value is offset by translating the approximate expression F1 (t) along the correction value axis. In this case, a predetermined offset point (predetermined time) τ-Pt is set to match yesterday's approximate expression F1 (t) with today's time zone, and the correction value is obtained by adding the Pt time to the offset point τ-Pt. Temporal offset is performed by aligning the time axes so that. Next, for example, when translating along the correction value axis by Px value, Px is added to or subtracted from yesterday's correction value prediction formula F1 (t), and today's correction value prediction formula F2 (t) is changed to a (x− Offset as Pt) ² + b (x−Pt) + c−Px.

FIG. 7 shows an example of rotational offset by rotating the approximate expression F1 (t). In this case, a predetermined offset point (predetermined time) τ-Pt is set to match yesterday's approximate expression F1 (t) with today's time zone, and the correction value is obtained by adding the Pt time to the offset point τ-Pt. Adjust the time axis so that they overlap. Next, for example, when the approximate expression F1 (t) of the previous day is rotated by θ, a rotation conversion process is performed on the correction value prediction expression F1 (t) of the previous day, and the correction value prediction expression F2 (t) of today is expressed as ( Offset conversion is performed as a (xcosθ + ysinθ) ² + b (xcosθ + ysinθ) + c + xsinθ) / cosθ.

  FIG. 8 shows an example of enlarging / reducing offset by enlarging / reducing the approximate expression F1 (t). In this case, a predetermined offset point (predetermined time) τ-Pt is set to match yesterday's approximate expression F1 (t) with today's time zone, and the correction value is obtained by adding the Pt time to the offset point τ-Pt. Adjust the time axis so that they overlap. Next, for example, when the approximate expression F1 (t) of the previous day is multiplied by 1 / P with respect to the time axis, today's correction value prediction is performed by multiplying x of the correction value prediction expression F1 (t) of the previous day by P. The equation F2 (t) is offset-transformed as a (x × P) + b (xx × P) + c. In this way, offset processing such as correction value offset, rotation offset, and enlargement / reduction offset can be performed. By applying offset processing in this way, correction is performed so that the average distance between data becomes the closest, and slight deviations can be corrected, making corrections more suitable for conditions such as ionosphere and weather conditions such as weather. A value prediction formula can be estimated and applied.

  Here, the amount of data communication for correction necessary for the position specifying method according to the present embodiment is compared. As described above, when the correction value prediction formula is predetermined, the data communication amount between the reference station 1 and the mobile station 3 is mainly defined by the information amount of the prediction formula coefficient. For example, when the correction formula prediction formula is predetermined by a polynomial, for example, the coefficients of the respective orders such as a quadratic formula, a cubic formula, and a quadratic formula are shown. In the case of a cubic equation, four coefficients are shown, and in the case of a quartic expression, five coefficients are shown.

  For example, when the positioning time is 1 hour, the correction value is distributed at intervals of 1 second, the number of visible satellites is 12, and the correction value prediction formula is applied to a cubic polynomial, it has 4 coefficients. As shown in FIG. 4B, the amount of data received on the mobile station 3 side is (latitude information of reference point position + longitude information of reference point position + generation time information + prediction coefficient information × 4) × visible satellite. Number = (8 + 8 + 12 + 8 × 4) × 12 = about 720 bytes. For easy understanding of the explanation, this information does not include information related to the offset processing.

  For example, in the technical idea disclosed in Patent Document 2, since correction values at the same time on the previous day are used as they are, it is necessary to transmit a huge amount of correction values corresponding to each satellite, and the mobile station 3 The amount of data received on the side is (correction value × number of visible satellites) × positioning time (seconds) = (8 × 12) × 3600 = about 345600 bytes.

  Therefore, even if information related to the offset process is added, the information of the correction value approximate expression conversion process (for example, about several bytes to several hundred bytes) is only transmitted, so that the data communication amount can be significantly reduced. Can do. Further, in order to transmit and receive the correction value prediction formula itself, in addition to the prediction formula coefficient information, data indicating the form and mode of the prediction formula (for example, an expression in any mode such as an exponential function, a logarithmic function, or a polynomial is applied) In addition, in the case of a polynomial, a linear expression is transmitted. Even in this case, the amount of data communication can be reduced as compared with the case where the correction value is transmitted / received. However, when only the coefficient of the prediction formula is transmitted / received, it is compared with the case where the correction value prediction formula itself is transmitted / received. Thus, the amount of information can be further reduced.

  According to the present embodiment, a correction value prediction formula that enables calculation of a correction value at a predetermined time point in the present or the future based on a correction value prediction formula that is approximated in advance from a correction value group acquired continuously in the past in the past. Therefore, it is possible to specify the position with high accuracy without using a huge correction value. In this case, since the correction value prediction formula stored in advance in the correction value prediction formula database 6 is selected, the correction value prediction formula can be determined quickly.

  In addition, the correction value prediction formula can be set by performing any one of the time offset, the correction value offset, the time and the rotation offset of the correction value, or the enlargement / reduction offset process, and various offset methods It becomes possible to cope with.

  Further, when the correction value prediction formula is estimated based on the correction value prediction formula approximated from the correction value group for one day on the previous day, the correction value prediction formula using the correction value group closer to today is used. Thus, the correction value prediction formula can be estimated, a more practical correction value prediction formula can be estimated, and the position can be specified with high accuracy. In addition, when estimating a correction value prediction formula based on weather conditions such as ionosphere and weather, the correction value prediction formula can be estimated based on a correction value prediction formula using a correction value group closer to the situation. Therefore, a more practical correction value prediction formula can be estimated and the position can be specified with high accuracy.

  Since the reference station 1 performs the correction value prediction formula calculation process and the mobile station 3 calculates the correction value, the calculation load can be distributed and processed at high speed. In particular, the processing load on the mobile station 3 side can be reduced by performing the calculation process of the correction value prediction formula with a large load by the reference station 1. The mobile station 3 may perform the correction value prediction formula calculation process.

In addition, since the reference station 1 transmits information on the correction value prediction formula or information on the coefficient thereof to the mobile station 3, the amount of data communication can be reduced as compared with the case where the correction value is transmitted.
In addition, in the conventional method, a large amount of past correction value data needs to be held, but in the method according to the present embodiment, it is only necessary to hold the coefficient of the correction value prediction formula, so that the storage capacity can be reduced.

Further, since the selection estimation process of the correction value prediction formula is executed by the reference station 1 and the calculation process of the correction value is executed by the mobile station 3, the load can be distributed and executed at high speed. .
Since the correction value at a predetermined point in time is calculated by using a correction value prediction formula that approximates the correction value for one cycle of the GPS satellite 2 in time, the correction value is corrected in real time as in the past. It is not necessary to acquire and correct the signal, and positioning can be performed at high speed without requiring communication time.

  Moreover, when using the method of patent document 1, since the most recent past data is used, the prediction period is about several tens of minutes. However, in the method according to the present embodiment, data for the past one period is used or Since it is possible to make a prediction for one period in the future, about six hours (for example, specifically, one period is 11 hours 58 minutes 2 seconds, but the GPS satellite 2 is visible from the mobile station 3 is about half. Therefore, it is possible to make a prediction for a longer time compared to the prior art.

  Further, according to the technical idea of Patent Document 1, since information must be stored again every time the reference point is changed, there is a possibility that a time during which correction values cannot be predicted by the mobile station 1 using a moving body such as a car may frequently occur. Therefore, it is not preferable for application to a moving body. In the present embodiment, when the reference point is changed, the correction value prediction formula can be always obtained by re-acquiring the correction value prediction formula from the reference station 1, which is suitable for use in a mobile object.

  Further, according to the technical idea of Patent Document 2, although it is necessary to hold a large amount of past correction value data, in the present embodiment, it is only necessary to communicate and hold the coefficient of the correction value prediction formula. It leads to reduction. That is, in the technical idea such as Patent Document 1 or 2, it is necessary to obtain correction values at intervals of, for example, 1 to 10 seconds, but in the technical idea according to the present embodiment, communication between the reference station 1 and the mobile station 3 is performed. Since the process is only when the coefficient of the correction value prediction formula is first transmitted / received and when the correction value prediction formula is re-acquired under a predetermined condition (when the ephemeris is switched or the vehicle travels for a fixed time (distance)), the communication frequency Can be greatly reduced.

(Second Embodiment)
FIG. 9 and FIG. 10 show the second embodiment of the present invention and more specifically show the processing sequence of the reference station and the mobile station. The same parts as those of the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 9 schematically shows the operation of the process on the mobile station side, and FIG. 10 schematically shows the operation of the process on the reference station side. As shown in FIG. 9, on the mobile station 3 side, after the ephemeris / pseudorange information is acquired (T1), positioning is performed independently (T2). When the mobile station 3 determines that communication with the reference station 1 is possible (T3: YES), the mobile station 3 transmits the result of positioning independently (approximately position) to the reference station 1.

  As shown in FIG. 10, when the base station 1 receives the information on the approximate position from the mobile station 3 (U1: YES), it accesses the correction value prediction formula database 6 of the base station 1 nationwide (U2). The reference station 1 that is closest to the information on the approximate position transmitted from (U3) is selected, and an approximate expression (coefficient of correction value prediction expression ( If necessary, the correction value prediction expression mode)) is calculated and selected (U4). Thereafter, the reference station 1 side performs offset processing on the approximate expression using the current correction value of the selected reference station 1 (U5).

  When the deviation between the correction value calculated by the approximate expression and the current correction value is equal to or less than a predetermined threshold value, the position information of the selected reference station 1, the coefficient of the approximate expression (correction value prediction expression), The time when the formula (coefficient) is generated is transmitted to the mobile station 3 (U7). If it is determined in step U6 that it is greater than the predetermined threshold value, the coefficient of the approximate expression (approximate form if necessary) is calculated from the correction value and time for the past one cycle of the selected reference station 1. , Select (U8). In this case, the correction value for one period in the past indicates correction value data different from the correction value for one period previously calculated in step U4. For example, when the approximate expression is calculated from the correction value data of the previous day in step U4, but it is determined in step U6 that the deviation is large, the correction value data of the previous day (in this case, two days before the present) is obtained. Use it to recalculate.

  Returning to FIG. 9, on the mobile station 3 side, when the position information of the reference station 1, the coefficient of the correction value prediction formula, and the generation time of the prediction formula are acquired from the reference station 1 (T5), the distance between the current position and the reference station 3 When the distance between the current position and the reference station 3 exceeds a predetermined threshold (T6: YES), or the correction value prediction formula is detected. If a predetermined time or more has elapsed since the generation of (T7: YES), the correction value prediction formula is discarded (T16), and the process returns to step T3 and is repeated. The process may be repeated after returning to step T1 or T2. It should be noted that if the distance between the current position and the reference station 3 is more than a predetermined distance, the reference point of the nearest reference station 3 needs to be used because the correction cannot be made with high accuracy.

  If both of the determination processes in steps T6 and T7 are equal to or less than the threshold value and NO is determined in steps T6 and T7, the ephemeris and the pseudo distance are acquired (T8), and based on the prediction formula. The correction value is calculated (T9), the pseudo distance is corrected (T10), and the positioning calculation is performed (T11).

  After this, whether the ephemeris has been switched (T12), whether the specified time has elapsed since the start of using the prediction formula (T13), whether the vehicle has traveled the specified distance after using the prediction formula (T14), and whether the reference station position and the current position are It is determined whether the specified distance is away (T15). If these conditions are satisfied (YES), the correction value prediction formula is discarded, and the process returns to step T3 to repeat the process. Similarly to the above, the process may be repeated by returning to step T1 or T2.

  As described above, according to the present embodiment, the correction value prediction formula is estimated based on the correction value prediction formula approximated and predicted from the correction value group acquired continuously in the past in the past. Since the DGPS positioning is performed by calculating the correction value using, and calculating the correction value at the current predetermined time point, the position can be specified with high accuracy without using a large amount of correction value data.

  On the mobile station 3 side, the correction value prediction formula is discarded when the determination condition is satisfied in steps T6, T7, and T12 to T15, and a new correction value prediction formula (coefficient or / and mode) is obtained from the reference station 1 side. Therefore, an applicable correction value prediction formula can be applied accurately, and an accurate correction value can be calculated.

(Other embodiments)
The present invention is not limited to the above embodiment, and for example, the following modifications or expansions are possible.
Although the DGPS method is applied, the present invention can also be applied to high-precision positioning by applying a virtual reference point such as a VRS (Vertical Reference Station) method.
Although it is applied to the mobile station 3, it can be similarly applied even to a device installed at a fixed position whose position cannot be clearly specified. In other words, the present invention can be applied to the device as long as it has a function of receiving correction values.

  The embodiment in which the server having the information distribution function is provided in the reference station 1 has been described. However, the server is not installed at the same location as the reference station 1 as long as the server can distribute information such as correction values, correction value prediction formulas or coefficients thereof. May be.

  In addition, when the traveling direction of the mobile station 3 is known in advance, the mobile station 3 has previously acquired correction value prediction formulas for several points in the traveling direction from the reference station 1 and has reached the traveling position. Sometimes, the correction value may be calculated by applying the correction value prediction formula.

  The offset calculation of the correction value prediction formula may be performed on the mobile station 3 side. In this case, even when the mobile station 3 cannot communicate with the reference station 1, the correction value prediction process can be performed accurately if the correction value and the correction value prediction formula for the day are held.

Principle diagram of positioning method shown in the first embodiment of the present invention System block diagram The figure which shows the communication sequence between the reference station and the mobile station Diagram showing data contents during transmission / reception Diagram showing the offset processing mode (part 1) Diagram showing the offset processing mode (2) Diagram showing the offset processing mode (No. 3) FIG. 4 is a diagram showing an offset processing mode (No. 4) The flowchart which shows roughly the process by the side of the mobile station shown about the 2nd Embodiment of this invention Flow chart schematically showing processing on the reference station side

Explanation of symbols

  In the drawing, 1 is a reference station, 2 is a GPS satellite, and 3 is a mobile station.

Claims (10)

A method for obtaining a correction value for measuring the position of the mobile station with high accuracy on at least either one of the mobile station side or the reference station side capable of communication connection with the mobile station,
An estimation process for estimating a correction value prediction expression that enables calculation of a correction value at a predetermined time point in the present or the future based on a correction value prediction expression approximated in advance from a correction value group acquired continuously in the past in the past A correction value prediction formula estimation method characterized by:   2. The correction value prediction formula estimation method according to claim 1, wherein the estimation processing is performed by selecting from correction value prediction formulas stored in advance in a storage unit.   3. The correction value according to claim 1, wherein at least one of time offset, correction value offset, time and rotation offset of the correction value, and enlargement / reduction offset is performed in the estimation process. Prediction formula estimation method.   The correction value prediction equation estimation according to any one of claims 1 to 3, wherein in the estimation process, a correction value prediction equation is estimated based on a correction value prediction equation approximated from the correction value group of the previous day. Method.   5. The correction value prediction formula estimation method according to claim 1, wherein in the estimation process, a correction value prediction formula is estimated based on weather conditions such as ionosphere and weather.   6. The correction value prediction equation estimation according to claim 1, wherein the reference station side distributes information on a correction value prediction equation mode or coefficient of the correction value prediction equation to the mobile station side. Method.   7. A calculation process for calculating a correction value at a predetermined time from the correction value prediction formula estimated by the estimation process after performing the estimation process of the correction value prediction formula estimation method according to claim 1. A method for calculating a position specifying correction value.   The position specifying correction according to claim 7, wherein the estimation process of the correction value prediction formula estimation method according to claim 1 is performed on a reference station side, and the calculation process is performed by a mobile station. How to calculate the value. At least one of the mobile station side or the reference station side capable of communication connection with the mobile station,
Executing a procedure for estimating a correction value prediction formula that enables calculation of a correction value at a predetermined time in the present or the future based on a correction value prediction formula that is approximated from a correction value group acquired continuously in the past in the past. The correction value prediction type estimation program characterized by the above. At least one of the mobile station side or the reference station side capable of communication connection with the mobile station,
A program for calculating a correction value for position identification, characterized by causing a procedure for calculating a correction value at a predetermined time point to be executed from a correction value prediction equation estimated by the correction value prediction equation estimation program according to claim 9.

Images