A method for selecting GNSS satellites to be used in positioning calculations based on an evaluation index of pseudorange errors used in vehicle positioning using GNSS, a method for calculating a reliability index of positioning solutions, and a vehicle positioning method and device using GNSS

Abstract

To provide a method of obtaining an evaluation index of a pseudo range error in positioning of a vehicle using a GNSS and a reliability index of positioning solution, a method of correcting a wave number bias by detecting a cycle slip, a method of obtaining the evaluation index of the pseudo range error and the reliability index of the positioning solution, a method of positioning a vehicle using the GNSS using the method of correcting the wave number bias by detecting the cycle slip and a device for the same.SOLUTION: A method of verifying a GNSS satellite using an evaluation index of a new pseudo range error, obtaining a reliability index of positioning solution to which a radio wave environment of a user station is reflected in real time and obtaining the evaluation index of the pseudo range error and the reliability index of the positioning solution, and a method of correcting a wave number bias by detecting a cycle slip are utilized to verify the GNSS satellite and perform positioning calculation of the user station and calculation of the reliability index of the positioning solution on which the radio wave environment of the user station is reflected in real time.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This invention is an evaluation index of pseudorange error used in vehicle positioning using GNSS. Method for selecting GNSS satellites to be used for positioning calculations A method for calculating the reliability index of the positioning solution and an evaluation index of this pseudorange error Method for selecting GNSS satellites to be used for positioning calculations The present invention relates to a method and an apparatus for vehicle positioning using GNSS that utilizes a method for calculating a reliability index of a positioning solution and a method for detecting cycle slips and correcting wave number biases, and in particular, to a pseudorange error evaluation index for extracting in real time a pseudorange error corresponding to the radio wave environment of a user station contained in received data in vehicle positioning using GNSS, and reflecting the pseudorange error corresponding to the radio wave environment of the user station extracted in real time in the reliability of the positioning solution. Method for selecting GNSS satellites to be used for positioning calculations And this Used in the method A method of selecting a GNSS satellite to be used for positioning calculation based on an evaluation index of pseudorange error, performing positioning calculation using data received from the selected GNSS satellite to obtain a positioning solution, and obtaining a reliability index of the positioning solution that reflects the radio wave environment of the user station in real time by obtaining a reliability index of the positioning solution. ,child Evaluation index of pseudorange error Method for selecting GNSS satellites to be used for positioning calculations and a method for calculating the reliability index of the positioning solution; By comparing and verifying the carrier phase observation value contained in the received data with a replica of the carrier phase observation value used as an evaluation index for the pseudorange error, This is a method and device for vehicle positioning using GNSS that detects cycle slips and corrects wave number bias. [Background technology]

[0002] The Satellite-Based Augmentation System (SBAS) is a method for reducing positioning errors in GNSS (Global Navigation Satellite System)-based positioning. SBAS monitors error factors, such as satellite failures and propagation anomalies, at ground stations and broadcasts correction information for these error factors and information on the reliability of this correction information to user stations as augmentation information. When performing positioning, user stations use the augmentation information to calculate and evaluate the positioning solution (hereinafter simply referred to as the positioning solution) and its reliability index (an index of the degree of error contained in the positioning result; in SBAS, this is called the Protection Level (PL)). This reduces the impact of error factors and ensures reliable positioning.

[0003] As a method for ensuring the reliability of positioning solutions like this SBAS, there is a method for estimating an error level in global navigation satellite measurements and ensuring the reliability of the estimation, and a global navigation device that implements the method, as described in Patent Document 1. The method for estimating an error level in global navigation satellite measurements and ensuring the reliability of the estimation, as described in Patent Document 1, is a method for estimating an integrity parameter for global navigation satellite measurements, implemented in a global navigation device, as shown in Figure 5, the method includes detecting local errors by the global navigation device and detecting errors associated with the satellite constellation by a ground base, and the local error σ loc,i The step of detecting includes a step Etp11 of calculating an error due to thermal noise and a step Etp12 of calculating noise due to multipath effects, wherein a local error is calculated using the error due to thermal noise and the noise due to multipath effects, and the method further includes a step of calculating an integrity parameter using the local error and an error associated with the satellite constellation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6262248 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] When calculating the protection level, which is an index of the reliability of SBAS positioning solutions, various error factors must be modeled and handled. The radio wave environment of aircraft, which are user stations in air navigation, is ideal compared to that of ground vehicles, making it easier to model various error factors. Therefore, current air navigation does not require real-time consideration of the radio wave environment. Since aircraft are always in a location where satellites are easily visible as long as they are in the sky, the reliability index of positioning solutions is calculated by treating various error factors under separate conditions. Furthermore, current reliability indexes of positioning solutions treat the pseudorange error of user stations as a steady-state model. User stations monitor the degradation of pseudorange quality due to radio wave environments (such as occlusion, multipath, and radio wave interference) that deviate from the model, and perform positioning by eliminating pseudoranges with test statistics above a threshold.

[0006] However, while aircraft have an ideal radio wave environment in some sense, ground vehicles have a less than ideal radio wave environment due to the presence of satellites that cannot be seen due to obstructions such as mountains, surrounding buildings and trees, as well as the effects of multipath. Therefore, even if SBAS, which is used in air navigation and can reduce the impact of error factors and perform reliable positioning, is used directly for vehicle positioning, it is not suitable for practical use because the radio wave environment of vehicles, which are user stations, is not ideal.

[0007] In addition, the conventional method of eliminating pseudo-range quality monitoring deals with the radio wave environment, which is not ideal, and the radio wave environment of the user station, which changes dramatically in real time, without considering it. This means that it becomes necessary to eliminate GNSS satellites with pseudo-ranges that do not meet the conditions, and the number of visible satellites required for positioning (four or more) becomes too high. butHowever, simply increasing the threshold for eliminating pseudoranges to avoid this problem would result in the reliability index of the positioning solution always being too large, making it unsuitable for practical use.

[0008] On the other hand, when carrier smoothing processing is used to reduce the effects of multipath, which can reduce multipath errors (range errors caused by multipath), there is a problem in that terrestrial obstructions can easily cause cycle slips in carrier phase observations at user stations moving on the ground. As the user station moves, the surrounding environment changes, and terrestrial obstructions can easily block the positioning signal. This blockage of the positioning signal causes a momentary interruption in the positioning signal, causing the carrier phase to lose tracking. Once carrier phase tracking is lost and the carrier smoothing processing is reset, even if a satellite is re-acquired, that satellite cannot be used for positioning calculations until the smoothing filter used in the carrier smoothing processing converges (100 seconds according to the SBAS standard). Therefore, even if there are enough visible satellites on the ground for positioning, the number of satellites whose multipath errors have been reduced by carrier smoothing processing may not be sufficient for positioning. Therefore, to maintain the carrier smoothing processing, it is necessary to detect cycle slips and, if a cycle slip occurs, to appropriately correct the wavenumber bias.

[0009] Taking these issues into consideration, this invention proposes a new pseudorange error evaluation index for vehicle positioning using GNSS. Method for selecting GNSS satellites to be used for positioning calculations and a method for calculating the reliability index of the positioning solution. ,child Evaluation index of pseudorange error Method for selecting GNSS satellites to be used for positioning calculationsThe present invention aims to provide a method and apparatus for positioning a vehicle using GNSS, which utilizes a method for calculating a reliability index of a positioning solution, a method for detecting cycle slips and correcting wave number biases. Furthermore, in vehicle positioning using GNSS, a pseudorange error corresponding to the radio wave environment of a user station contained in received data is extracted in real time, and a pseudorange error evaluation index is calculated to reflect the pseudorange error corresponding to the radio wave environment of the user station extracted in real time in the reliability of the positioning solution. Method for selecting GNSS satellites to be used for positioning calculations And this Used in the method A method of selecting a GNSS satellite to be used for positioning calculation based on an evaluation index of pseudorange error, performing positioning calculation using data received from the selected GNSS satellite to obtain a positioning solution, and obtaining a reliability index of the positioning solution that reflects the radio wave environment of the user station in real time by obtaining a reliability index of the positioning solution. ,child Evaluation index of pseudorange error Method for selecting GNSS satellites to be used for positioning calculations and a method for calculating a reliability index of the positioning solution; By comparing and verifying the carrier phase observation value contained in the received data with a replica of the carrier phase observation value used as an evaluation index for the pseudorange error, The present invention aims to provide a method and device for vehicle positioning using GNSS that utilizes a method for detecting cycle slips and correcting wave number bias. [Means for solving the problem]

[0010] The invention of claim 1 is an evaluation index of pseudorange error used in vehicle positioning using GNSS, which calculates positioning solutions using data received from GNSS satellites at a user station. A method for selecting GNSS satellites to be used for positioning calculations by In the above, the evaluation index of the pseudorange error is an index based on CMC that combines at least one of the pseudorange or carrier smoothing pseudorange with a replica of the carrier phase observation value generated from the geometric change between the user station and the GNSS satellite received at the user station. Method for selecting GNSS satellites to be used for positioning calculations is.

[0011] The invention according to claim 2 is the invention according to claim 1, wherein the evaluation index of the pseudorange error is moreover It is an index that combines the time variation of the autocorrelation result of the received signal and the carrier phase observation value.

[0012] Claim3 The invention according to the present invention is as follows: 2 In the invention according to any one of the above, the evaluation index of the pseudorange error is an index using a signal for each constellation.

[0013] Claim 4 The invention according to the present invention is as follows: 2 In the invention according to any one of the above, the evaluation index of the pseudorange error is The satellite signals of GNSS satellites used to calculate the evaluation index of pseudorange errors It is an index that uses signals of different constellations.

[0014] The invention according to claim 5 is characterized in that the evaluation index of the pseudorange error is the same as that according to claim 1. Used in the method The evaluation index of the pseudorange error and the Used in the method The pseudorange error evaluation index is characterized in that the pseudorange error evaluation index is a pseudorange error evaluation index obtained by combining evaluation indexes of pseudorange errors of the same constellation.

[0015] The invention of claim 6 is the invention of either claim 1 or claim 5, wherein the evaluation index of the pseudorange error is a combination of evaluation indexes of pseudorange errors based on the deviation between carrier smoothing pseudoranges processed by multiple time constants, and evaluation indexes of pseudorange errors of the same constellation.

[0016] The invention of claim 7 is an invention of claim 1 or any one of claims 5 to 6, which further provides an evaluation index for pseudorange errors that combines evaluation indexes for pseudorange errors of the same constellation, such as evaluation indexes for pseudorange errors due to changes in pseudorange, changes in carrier smoothing pseudorange, or changes in carrier phase observation values and changes in the geometric distance between a user station and a GNSS satellite received by the user station and the amount of deviation from the receiver clock drift.

[0017] The invention of claim 8 is an invention of claim 1 or any one of claims 5 to 7, which further provides an evaluation index for pseudorange errors that combines evaluation indexes for pseudorange errors using multiple frequencies, carrier smoothing pseudoranges, and pseudorange error evaluation indexes that utilize the difference in multipath error of carrier phase observation values with evaluation indexes for pseudorange errors of the same constellation.

[0018] The invention of claim 9 is an invention of claim 1 or any one of claims 5 to 8, which further provides an evaluation index for pseudorange errors that utilizes time fluctuations in the autocorrelation results of received signals and combines evaluation indexes for pseudorange errors of the same constellation.

[0019] The invention according to claim 10 is characterized in that the evaluation index of the pseudorange error is the same as that according to claim 1. Used in the method The evaluation index of the pseudorange error and the Used in the method The pseudorange error evaluation index is characterized by being a pseudorange error evaluation index that is a combination of the pseudorange error evaluation index and the pseudorange error evaluation index of a different constellation.

[0020] The invention of claim 11 is the invention of either claim 1 or claim 10, wherein the evaluation index of the pseudorange error is a combination of evaluation indexes of pseudorange errors based on the deviation between carrier smoothing pseudoranges processed by multiple time constants, and evaluation indexes of pseudorange errors of the same constellation.

[0021] The invention according to claim 12 is an invention according to any one of claim 1 or claim 10 to claim 11, The evaluation index of the pseudorange error isFurthermore, this is a pseudorange error evaluation index that combines evaluation indexes of pseudorange errors due to the change in pseudorange, the change in carrier smoothing pseudorange, or the change in carrier phase observation value and the change in the geometric distance between the user station and the GNSS satellite received at the user station and the deviation from the receiver clock drift, with evaluation indexes of pseudorange errors of the same constellation.

[0022] The invention according to claim 13 is an invention according to any one of claim 1 or claims 10 to 12, The evaluation index of the pseudorange error is Furthermore, this is a pseudorange error evaluation index that combines pseudorange error evaluation indexes using multiple frequencies, carrier smoothing pseudorange, and pseudorange error evaluation indexes that utilize the difference in multipath error of carrier phase observation values with evaluation indexes of pseudorange errors for the same constellation.

[0023] The invention according to claim 14 is an invention according to claim 1 or any one of claims 10 to 13, The evaluation index of the pseudorange error is Furthermore, the pseudorange error evaluation index is a combination of pseudorange error evaluation indexes that utilize the time fluctuation of the autocorrelation result of the received signal and evaluation indexes of pseudorange errors of the same constellation.

[0024] Claim 1 5 The invention according to the present invention is as follows: 4 In any one of the above-mentioned inventions, the carrier phase observation value is a carrier phase observation value in which a cycle slip is detected and the wave number bias of the carrier phase observation value of the received data of the GNSS satellite in which a cycle slip has occurred is corrected by comparing (a) the carrier phase observation value of the received data of the GNSS satellite received at the user station with (b) a replica of the carrier phase observation value generated from the geometric change between the user station and the GNSS satellite received at the user station.

[0025] Claim 1 6 The invention according to the present invention is as follows: 4 In any one of the above-mentioned inventions, the carrier phase observation value is (a) a carrier phase observation value of reception data of a GNSS satellite received at a user station, and (b) Using the time variation of the autocorrelation results of the received signalBy combining this with an evaluation index for pseudorange error, cycle slips are detected, and (c) carrier phase observation values are obtained by correcting the wave number bias of the carrier phase observation values of the received data from the GNSS satellite where a cycle slip has occurred, using a replica of the carrier phase observation value generated from the geometric changes between the user station and the GNSS satellite received at the user station.

[0026] The invention of claim 17 relates to a reliability index of a positioning solution used in vehicle positioning using GNSS, which calculates a positioning solution from data received from GNSS satellites at a user station, and is based on the radio wave environment of the user station contained in the data received from GNSS satellites. Used in the method This method for determining a reliability index of a positioning solution is characterized by: extracting an evaluation index of a pseudorange error for each satellite in real time; determining a limit value of a multipath error for each satellite that is necessary and sufficient to ensure completeness from the evaluation index of the pseudorange error extracted in real time; and determining a reliability index of a positioning solution that reflects the radio wave environment of a user station in real time from the limit value of the multipath error determined for each satellite.

[0027] The invention of claim 18 is a vehicle positioning method using GNSS, which selects a GNSS satellite to be used for positioning calculation of a user station by verifying the GNSS satellite using reception data of the GNSS satellite received by the user station, and calculates a positioning solution and a reliability index of the positioning solution using the reception data of the selected GNSS satellite, and further comprises: Used in the methodThis is a vehicle positioning method using GNSS, characterized by extracting a pseudorange error evaluation index for each satellite in real time, determining a multipath error limit value for each satellite that is necessary and sufficient to ensure completeness from this pseudorange error evaluation index extracted in real time, selecting a GNSS satellite to be used in the positioning calculation of a user station by testing the GNSS satellite using the multipath error limit value determined for each satellite, calculating a positioning solution using the received data from the selected GNSS satellite, and calculating a reliability index for the positioning solution that reflects the radio wave environment of the user station in real time.

[0028] The invention according to claim 19 is , request Request 1 to 8 In the invention , Yu From the GNSS satellite data received at the user station (a) The carrier phase observation value of the received data of the GNSS satellite received at the user station is compared with (b) a replica of the carrier phase observation value generated from the geometric change between the user station and the GNSS satellite received at the user station, thereby verifying the carrier phase observation value. Detecting cycle slips and disabling the detected cycle slips Carrier phase observation value of received data from GNSS satellites where the This corrects the wavenumber bias of the

[0029] The invention of claim 20, in the invention of claim 18, detects a cycle slip from the received data of a GNSS satellite received at a user station by combining (a) a carrier phase observation value of the received data of the GNSS satellite received at the user station and (b) an evaluation index of a pseudorange error that utilizes time fluctuations in the autocorrelation results of the received signal, and (c) corrects the wavenumber bias of the carrier phase observation value of the received data of the GNSS satellite in which a cycle slip has occurred by using a replica of the carrier phase observation value generated from geometric changes between the user station and the GNSS satellite received at the user station.

[0030] Claim 2 1 The invention according to claim 1 8 ~Claims 20 In the invention relating to any one of the above, a positioning solution and its reliability index are calculated individually for each constellation, the reliability index of the positioning solution for each constellation is compared to determine which constellations have poor positioning performance, and the GNSS satellites of the constellations with poor positioning performance are inspected to select GNSS satellites to be used for positioning calculations of a user station.

[0031] The invention of claim 22 is a vehicle positioning device using GNSS, which has means for selecting a GNSS satellite to be used for positioning calculation of the user station by verifying the GNSS satellite using reception data of the GNSS satellite received by the user station, and means for calculating a positioning solution and a reliability index of the positioning solution using the reception data of the selected GNSS satellite, and further comprises a means for calculating a reliability index of the positioning solution according to the radio wave environment of the user station contained in the reception data of the GNSS satellite received by the user station, the means for calculating a reliability index of the positioning solution according to the radio wave environment of the user station, the means for calculating a reliability index of the positioning solution according to the radio wave environment of the user station, the reliability index of the positioning solution according to the reception data of the GNSS satellite received by ... reliability index of the positioning solution according to the radio wave environment of the user station, the reliability index of the positioning solution according to the reception data of the GNSS satellite received by the user station, the reliability index of the positioning solution according to the reception data of the GNSS satellite Used in the method This is a vehicle positioning device using GNSS, characterized by comprising: means for extracting a pseudorange error evaluation index for each satellite in real time; means for calculating a multipath error limit value for each satellite that is necessary and sufficient to ensure completeness from this pseudorange error evaluation index extracted in real time; means for selecting a GNSS satellite to be used for user station positioning calculations by testing the GNSS satellite using the multipath error limit values calculated for each satellite, and means for calculating a positioning solution using received data from the selected GNSS satellite and a reliability index for the positioning solution that reflects the user station's radio wave environment in real time.

[0032] The invention according to claim 23 is , request Request 2 2 to In the invention , Yu From the GNSS satellite data received at the user station (a) The carrier phase observation value of the received data of the GNSS satellite received at the user station is compared with (b) a replica of the carrier phase observation value generated from the geometric change between the user station and the GNSS satellite received at the user station, thereby verifying the carrier phase observation value. Detecting cycle slips and disabling the detected cycle slips Carrier phase observation value of received data from GNSS satellites where the The present invention further includes a means for correcting the wavenumber bias of the signal.

[0033] The invention of claim 24 is the invention of claim 22, further comprising means for detecting a cycle slip from the reception data of a GNSS satellite received at a user station by combining (a) a carrier phase observation value of the reception data of the GNSS satellite received at the user station and (b) an evaluation index of a pseudorange error that utilizes time fluctuations in the autocorrelation results of the reception signal, and (c) correcting a wavenumber bias of the carrier phase observation value of the reception data of the GNSS satellite in which a cycle slip has occurred, using a replica of the carrier phase observation value generated from geometric changes between the user station and the GNSS satellite received at the user station.

[0034] Claim 2 5 The invention according to claim 2 2 ~Claim 2 4In the invention according to any one of the above, the present invention further comprises means for calculating a positioning solution and a reliability index thereof individually for each constellation, means for determining a constellation with poor positioning performance by comparing the reliability indexes of the positioning solutions for each constellation, and means for selecting a GNSS satellite to be used for positioning calculation of a user station by inspecting the GNSS satellites of the constellation with poor positioning performance. [Effects of the Invention]

[0035] Claim 1~Claim 1 4 The invention is configured as described above, and therefore can provide a new pseudorange error evaluation index that can be used for user stations (ground vehicles) that are in poor and significantly variable radio wave environments, unlike aircraft that are in ideal radio wave environments.

[0036] Claim 1 7 As the invention is configured as described above, it can be used for user stations (ground vehicles) that are in poor or significantly changing radio wave environments, unlike aircraft that are in ideal radio wave environments, and it can provide a reliability index for positioning solutions that reflects the radio wave environment of the user station in real time.

[0037] request The inventions according to claims 15 and 16 are configured as described above, and therefore can detect cycle slips and correct wavenumber biases by utilizing a new pseudorange error evaluation index that can be used even for user stations (ground vehicles) whose radio wave environments change significantly.

[0038] Claim 1 8 and claim 2 2The invention is configured as described above, and therefore provides a GNSS-based vehicle positioning method and device that can be used for user stations (ground vehicles) that are subject to poor and significantly changing radio wave environments, unlike aircraft that are subject to ideal radio wave environments. Furthermore, even if a pseudorange error (of a GNSS satellite) is rejected under uniform conditions in conventional methods during GNSS satellite testing, by rigorously evaluating the pseudorange error of the GNSS satellite in real time, the GNSS satellite can be used without necessarily being rejected, enabling user station positioning calculations. Furthermore, it is possible to calculate a reliability index for a positioning solution that reflects the user station's radio wave environment in real time, in addition to the user station positioning calculations.

[0039] Claim 2 1 and claim 2 5 The invention is configured as described above, and is therefore capable of determining and testing constellations with poor positioning performance. Therefore, when calculating the positioning performance and determining the reliability index of a user station, it is possible to select a GNSS satellite of an appropriate constellation that reflects the user's radio wave environment in real time.

[0040] Claim 19 , claim 20, claim 23 and claim 2 4 The invention is configured as described above. , request The same effects as those of claims 15 and 16 are achieved. [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a schematic diagram illustrating a vehicle positioning device using GNSS according to a first embodiment of the present invention. FIG. [Figure 2] 1 is a flowchart illustrating a process performed by a calculation unit of a vehicle positioning device using GNSS according to a first embodiment of the present invention when positioning a vehicle using GNSS. [Figure 3]FIG. 10 is a diagram showing a second embodiment of the present invention, illustrating the relationship between the evaluation index of the pseudorange error used in vehicle positioning using GNSS of the present invention, and the multipath error and its limit value, where (a) is a diagram showing the relationship between the evaluation index of the pseudorange error, and the multipath error and its limit value, and (b) is a diagram showing the probability density function of the multipath error corresponding to the evaluation index C1 of the pseudorange error in (a). [Figure 4] FIG. 10 is a diagram showing a second embodiment of the present invention, illustrating the relationship between the evaluation index of the pseudorange error used in vehicle positioning using GNSS of the present invention, and the multipath error and its limit value, where (a) is a diagram showing the relationship between the evaluation index of the pseudorange error, and the multipath error and its limit value, and (b) is a diagram showing the probability density function of the multipath error corresponding to the evaluation index C of the pseudorange error in (a). [Figure 5] 1 is a prior art example block flow diagram illustrating a method for estimating the error level in global navigation satellite measurements and ensuring the reliability of said estimates, and a global navigation device implementing said method; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0042] In a vehicle positioning method using GNSS in which a positioning solution is calculated using data received from GNSS satellites at a user station, an evaluation index of a pseudorange error corresponding to the radio wave environment of the user station, which is included in the data received from GNSS satellites at the user station, is extracted in real time for each satellite, a limit value of the multipath error necessary and sufficient to ensure completeness is calculated for each satellite from the evaluation index of the pseudorange error extracted in real time, and a reliability index of a positioning solution that reflects the radio wave environment of the user station in real time is calculated from the limit value of the multipath error calculated for each satellite. The evaluation index of the pseudorange error is an index based on CMC, which combines at least one of the pseudorange or carrier-smoothing pseudorange with a replica of the carrier phase observation value generated from the geometric change between the user station and the GNSS satellite received at the user station; an index based on the amount of deviation between the carrier-smoothing pseudorange processed with multiple time constants; an index based on the amount of deviation between the change in pseudorange, the change in carrier-smoothing pseudorange, or the change in the carrier phase observation value and the change in the geometric distance between the user station and the GNSS satellite received at the user station and the receiver clock drift; and a multipath error of the pseudorange, carrier-smoothing pseudorange, and carrier phase observation value using multiple frequencies. or an index that utilizes the difference between the autocorrelation results of the received signal and the time fluctuation of the autocorrelation results of the received signal, or an index that combines these indices with the time fluctuation of the autocorrelation results of the received signal and the carrier phase observation value, or an index that further uses signals for each constellation in addition to these indices, or an index that further uses signals of different constellations in addition to these indices, or an index that combines these indices with indices of the same constellation, or an index that combines these indices including indices of different constellations, or an index that combines these indices and these indices while also taking the constellation into consideration. Regarding cycle slips, (a) the carrier phase observation value of the received data from the GNSS satellite received at the user station is compared with (b) a replica of the carrier phase observation value generated from the geometric change between the user station and the GNSS satellite received at the user station to verify the carrier phase observation value, and the cycle slip is detected and the wave number bias of the carrier phase observation value of the received data from the GNSS satellite in which the cycle slip occurred is corrected, or the cycle slip is detected by combining (a) the carrier phase observation value of the received data from the GNSS satellite received at the user station with (b) an evaluation index for the pseudorange error that uses the time fluctuation of the autocorrelation result of the received signal, and (c) the wave number bias of the carrier phase observation value of the received data from the GNSS satellite in which the cycle slip occurred is corrected using a replica of the carrier phase observation value generated from the geometric change between the user station and the GNSS satellite received at the user station. Detect cycle slips, correct wave number biases, and calibrate GNSS satellites using one of these pseudorange error evaluation indices. Calculate the reliability index of the positioning solution that reflects the radio wave environment of the user station in real time. Compare the reliability index of the positioning solution for each constellation to determine which constellations have poor positioning performance. Then calibrate the GNSS satellites of these constellations. A vehicle positioning method using GNSS in which a GNSS satellite to be used for positioning calculation of a user station is selected by performing GNSS satellite verification using data received from the GNSS satellite at the user station, and a positioning solution and a reliability index of the positioning solution are calculated using the data received from the selected GNSS satellite, This is a vehicle positioning method using GNSS that selects GNSS satellites to be used for user station positioning calculations, calculates positioning solutions using data received from the selected GNSS satellites, and calculates a reliability index for the positioning solutions that reflects the user station's radio wave environment in real time. [Example]

[0043] A first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2 show a first embodiment of the present invention, in which Fig. 1 is a schematic diagram showing a vehicle positioning device using GNSS according to the present invention, and Fig. 2 is a flowchart showing the processing performed by a calculation unit of the vehicle positioning device using GNSS according to the present invention when positioning a vehicle using GNSS.

[0044] As shown in Figure 1, the vehicle positioning device 1 using GNSS of the present invention is a device that uses positioning signals from GNSS satellites 2 (2a, 2b, etc.) - i.e., satellite signals - to perform positioning of a ground vehicle, which is a user station 3. The vehicle positioning device 1 is composed of an antenna 4 placed in a position where it is easy to receive satellite signals, such as on top of the user station 3, a receiver 5, a processing unit 6, a display unit 7, a geospatial information database 8, an inertial measurement unit (IMU) 9, a camera 10, and a tachometer generator 11.

[0045] The GNSS satellites 2 (2a, 2b, etc.) are navigation satellites used in GNSS, including GPS. In this embodiment, the GNSS satellites 2 (2a, 2b, etc.) are GPS satellites operating at three frequencies (L1: 1.57542 GHz / L2: 1.22760 GHz / L5: 1.117645 GHz), and each GPS satellite transmits signals necessary for positioning, including its own orbit information. The signals transmitted from these GNSS satellites 2 (2a, 2b, etc.) are satellite signals. In this embodiment, L1-band signals, i.e., L1 signals, are used as satellite signals. The received satellite signal data used for signal processing and analysis uses the carrier phase observation values of the L1 signals, but frequency bands other than the L1 signal can also be used. In addition to the American GPS satellites that transmit signals in three frequency bands, L1, L2, and L5, other GNSS satellites (2a, 2b, etc.) that can be used include GPS satellites that transmit only L1 and L2 bands and do not transmit L5 band signals, as well as satellites that transmit signals that can be used for navigation, such as Russia's GLONASS satellites, Japan's Quasi-Zenith Satellite System, Europe's Galileo, China's Beidou, and India's GAGAN. In addition to the satellite signals transmitted from the GNSS satellites (2a, 2b, etc.), radio signals transmitted from terrestrial transmitters such as terrestrial reference stations with known positions and given transmission positions can also be used.

[0046] The user station 3 is a ground vehicle, i.e., a mobile object moving on the ground, and includes land vehicles such as automobiles and railroad vehicles, as well as ships in harbors and aircraft moving on airport surfaces. Unlike the ideal radio wave environment of an aircraft flying in the open air, the radio wave environment of the user station 3 is not ideal due to the presence of satellites that are obscured by obstructions such as mountains, surrounding buildings, and trees, as well as the effects of multipath. In addition, the radio wave environment changes significantly as the user station 3 moves on the ground. In this embodiment, the user station 3 is a railroad vehicle.

[0047] Receiver 5 is a receiver capable of receiving and processing the RF signal of a satellite signal received by antenna 4, and transmits this received signal, i.e., the received data of the received satellite signal, to calculation unit 6 by wired, wireless or offline method. Receiver 5 also has the function of receiving SBAS augmentation information (correction information for error factors such as satellite failure and propagation abnormalities, and information on the reliability of this correction information) which is mainly used in air navigation.

[0048] The calculation unit 6 has the functions of performing signal processing and analysis of the received data of input satellite signals, and performing positioning of the user station 3 in a radio wave environment that changes significantly, as well as the functions of extracting in real time for each GNSS satellite 2 an evaluation index of the pseudorange error that corresponds to the radio wave environment of the user station 3, which is contained in the received data of the GNSS satellites; determining, from the evaluation index of the pseudorange error extracted in real time, for each GNSS satellite 2 a limit value of the multipath error, which is a range error caused by multipath that is necessary and sufficient to ensure completeness; performing calibration of the GNSS satellite 2 using the limit value of the multipath error determined for each GNSS satellite 2; selecting a GNSS satellite 2 to be used for positioning calculations of the user station 3 by calibration of the GNSS satellite 2; calculating a positioning solution, which is the result of the positioning calculations of the user station 3, using the received data of the selected GNSS satellite 2; and calculating a reliability index of the positioning solution that reflects the limit value of the multipath error determined for each GNSS satellite 2.

[0049] The display unit 7 has the function of displaying the position of the user station 3 calculated by the calculation unit 6 and the reliability index of the positioning solution of this user station 3.

[0050] The geospatial information database 8 is a database of location information indicating the location of specific points or areas in space, and information on various events associated with this location information, including a database of a geographic information system (GIS) and a database of survey data for railway track positions. The inertial measurement unit (IMU) 9 is a device that detects three-dimensional angular velocity and acceleration, and in this embodiment is a sensor that detects the translational motion and attitude changes of the user station 3, which is a ground vehicle. The camera 10 captures images of the surroundings of the user station 3, and the processing unit 6 performs image analysis of this captured data to determine the change in geometric distance traveled by the user station 3, which is a ground vehicle. The tachometer generator 11 detects the rotational speed by generating a DC voltage proportional to the rotational speed, and can calculate the distance from the number of rotations of the wheels of the user station 3 and their wheel diameter, making it possible to determine the change in geometric distance traveled by the user station 3, which is a moving object. The geospatial information database 8, inertial measurement unit (IMU) 9, camera 10, and tachometer generator 11 are all components for determining the change in position of the user station 3, which is a ground vehicle, and any one of these components or a combination of these components may be used. The change in position of the user station 3 determined from these components is used to generate a replica of the user station 3 and the carrier phase observation value generated from the geometric change of the GNSS satellites received by the user station 3.

[0051] Next, the operation will be described with reference to FIGS. First, satellite signals from GNSS satellites 2 (2a, 2b, etc.) are received by the antenna 4 of the user station 3. The RF signals of the satellite signals received by the antenna 4 are input to the receiver 5, and the received data is transmitted to the calculation unit 6. Based on the received satellite signal data input to the calculation unit 6, the position of the user station 3 is determined, and the radio wave environment changes significantly as the user station 3 moves through a radio wave environment affected by factors such as shadowing and multipath interference. The calculation unit 6 also calculates a reliability index for the positioning solution. Data from the geospatial information database 8, inertial measurement unit (IMU) 9, camera 10, and tachometer generator 11 is also transmitted to the calculation unit 6. The calculation unit 6 uses this data to generate replicas of the carrier phase observation values. The calculation unit 6 uses these replicas to calculate a pseudorange error evaluation index, detect cycle slips, and correct the wave number bias. The pseudorange error evaluation index and the wave number bias correction results when a cycle slip is detected are used to calculate the position of the user station 3 and the reliability index for the positioning solution. The positioning results of the user station 3 calculated by the calculation unit 6 and the reliability index of the positioning solutions are displayed on the display unit 7 as the position of the user station 3 and the reliability index of the positioning solutions.

[0052] Next, the calculation of the position of the user station 3 and the calculation of the reliability index of this positioning solution performed by the calculation unit 6 will be described with reference to FIG. First, the received data of satellite signals from GNSS satellites 2 (2a, 2b...) received by the antenna 4 is input to the calculation unit 6 together with SBAS augmentation information (step 50). This SBAS augmentation information is used to check for abnormal satellites (GNSS satellites 2 (2a, 2b...) experiencing satellite failure, etc.) (step 51). If an abnormal satellite is found, the GNSS satellite 2 (2a, 2b...) is excluded from the satellites used in the positioning calculations of the user station 3 (step 52). Furthermore, from the received data input to the calculation unit 6, NLOS (Non Line of Sight: invisible (satellite)) GNSS satellites 2 (2a, 2b...) are excluded from the satellites used in the positioning calculations of the user station 3 (step 53), and a cycle slip in the carrier phase is detected (step 54). If a cycle slip is detected for a GNSS satellite 2 (2a, 2b...), it is either excluded from the satellites used in the positioning calculations of the user station 3, or its wavenumber bias is corrected.

[0053] In this way, abnormal satellites and invisible satellites are eliminated, and a pseudorange error evaluation index corresponding to the radio wave environment of the user station 3 is calculated and extracted in real time for each GNSS satellite 2 (step 55), which is included in the received data of GNSS satellites 2 (2a, 2b, etc.) in LOS (Line of Sight: visible (satellite)) that have been excluded from the satellites used in the positioning calculations of the user station 3 due to the detection of a cycle slip or that have been selected due to a wavenumber bias correction (step 56). From this pseudorange error evaluation index extracted in real time, a multipath error limit value necessary and sufficient to ensure the desired completeness is calculated for each GNSS satellite 2 (step 56). The multipath error limit value calculated for each GNSS satellite 2 is used to calibrate the GNSS satellites 2 (2a, 2b, etc.), and the GNSS satellites 2 (2a, 2b, etc.) to be used in the positioning calculations of the user station 3 are selected.

[0054] Using only these selected GNSS satellites 2 (2a, 2b, etc.), the target GNSS satellite 2 is corrected using its received data, the limit value of the multipath error, and the SBAS augmentation information, and the positioning calculation for the user station 3 is performed (step 57), and a reliability index of the positioning solution is calculated that reflects the limit value of the multipath error determined for each GNSS satellite 2 (step 58).

[0055] The positioning result of the user station 3 calculated in this way and the reliability index of the positioning solution are output to the display unit 7 (step 59), and the position of the user station 3 and its protection level (the reliability index of the positioning solution) are displayed on the display unit 7.

[0056] In the GNSS-based vehicle positioning device of the present invention, excluding NLOS GNSS satellites 2 (step 53) is not an essential step. This is because the limit value of the multipath error obtained from the evaluation index of the pseudorange error corresponding to the radio wave environment of the user station 3, which is included in the reception data from the NLOS GNSS satellites 2 (2a, 2b, etc.), becomes a large value that is not suitable for practical use, and as a result, the GNSS satellites 2 (2a, 2b, etc.) will be excluded from the GNSS satellites 2 (2a, 2b, etc.) used in the positioning calculations of the user station 3.

[0057] Next, we will explain a method performed by the calculation unit 6 to detect cycle slips from the reception data of the GNSS satellites 2 (2a, 2b, etc.) received by the user station 3 and correct the wave number bias. In this embodiment, we will explain a method to detect cycle slips from the reception data of the GNSS satellites 2 (2a, 2b, etc.) received by the user station 3 and correct the wave number bias, using the geospatial information database 8 and data from the speedometer (not shown) of the user station 3.

[0058] In this embodiment, the geospatial information database 8 utilizes a geographic information system (GIS) database. Furthermore, since the user station 3 in this embodiment is a railway vehicle, as described above, a commonly used map matching technique can also be used to determine the unit vector of the velocity of the user station 3 from this GIS data. Multiplying this unit vector of the velocity of the user station 3 by the speed obtained from the speedometer determines the three velocity components (Vx, Vy, Vz) of the user station 3. The change in position of the user station 3 is calculated from these three velocity components, and the geometric change between the user station 3 and the GNSS satellites 2 (2a, 2b,...) received by the user station 3 can be calculated. By comparing the replica of the carrier phase observation value generated from the geometric change between this user station 3 and the GNSS satellite 2 (2a, 2b...) received by the user station 3 with the carrier phase observation value of the received data of GNSS satellite 2 (2a, 2b...) received by the user station 3 and verifying the carrier phase observation value of the received data of GNSS satellite 2 (2a, 2b...) received by the user station 3, it is possible to detect a cycle slip and correct the wavenumber bias of the carrier phase observation value of the received data of the GNSS satellite 2 (2a, 2b...) in which a cycle slip occurred. This verification is performed by verifying the amount of carrier phase change using the estimated receiver clock drift, and is performed for each GNSS satellite 2 (2a, 2b...).

[0059] More specifically, as shown in Equation 2 (described later), the carrier phase observation value includes the clock error between the GNSS satellite 2 (2a, 2b, etc.) and the receiver, the ionospheric delay, and the tropospheric delay. Of these, the clock error, ionospheric delay, and tropospheric delay of the GNSS satellite 2 (2a, 2b, etc.) can be corrected and removed using SBAS augmentation information. The remaining receiver clock error can be estimated by taking advantage of the property that it is contained in all observation values, or by using a stable atomic clock as an external clock to reduce the fluctuation of the receiver clock error. The replica of the carrier phase observation value is generated by taking into account the geometric change between the user station 3 and the GNSS satellite 2 (2a, 2b, etc.) received by the user station 3, as well as the clock error, ionospheric delay, tropospheric delay, and estimated receiver clock error (receiver clock drift) of the GNSS satellite 2 (2a, 2b, etc.) that can be corrected using SBAS augmentation information. The replica of the carrier phase observation value thus generated is compared with the carrier phase observation value to verify the amount of carrier phase change, thereby validating the carrier phase observation value.If a cycle slip is detected, the jump (discontinuity) of an integer wavelength that exists between observation values adjacent to the time when the cycle slip occurred is corrected by estimating the true fluctuation range based on the replica of the transmitted phase observation value.

[0060] Note that a method for detecting a cycle slip from the reception data of a GNSS satellite 2 (2a, 2b, etc.) received by the user station 3 and correcting the wave number bias may include detecting a cycle slip by combining the carrier phase observation value of the reception data of the GNSS satellite 2 (2a, 2b, etc.) received by the user station 3 with a pseudorange error evaluation index that utilizes time fluctuations in the autocorrelation results of the reception signal, which is one of the pseudorange error evaluation indexes described below, and correcting the wave number bias of the carrier phase observation value of the reception data of the GNSS satellite 2 (2a, 2b, etc.) in which a cycle slip has occurred, using a replica of the carrier phase observation value generated from geometric changes between the user station 3 and the GNSS satellite 2 (2a, 2b, etc.) received by the user station 3.

[0061] Next, we will explain the validation of GNSS satellites 2 (2a, 2b, etc.) used in the positioning calculation of the user station 3 (step 57) and the calculation of the reliability index of the positioning solution (step 58). Conventional methods for validating GNSS satellites include, as described above, treating the pseudorange error of the user station 3 as a steady-state model, monitoring degradation of pseudorange quality due to a radio wave environment (obstruction, multipath, radio wave interference) that deviates from the steady-state model, and eliminating pseudoranges (GNSS satellites) whose validation statistics are above a threshold, or eliminating GNSS satellites with extremely low reception strength. These GNSS satellite validation methods, which have been used for aircraft navigation in an ideal radio wave environment, deal with the radio wave environment of the user station 3 under uniform conditions without taking into account in real time the radio wave environment of the user station 3, which is not ideal and changes significantly, as described above. Therefore, it becomes necessary to reject pseudoranges (GNSS satellites) that do not meet the conditions, which poses a problem of increasing the time during which positioning is unavailable even if the number of visible satellites required for positioning (four or more) is available. To avoid this problem, if the pseudorange error caused by quality degradation due to a non-ideal and significantly changing radio wave environment is simply incorporated into the steady-state model in order to relax the threshold for eliminating pseudoranges, the limit value of the multipath error that is necessary and sufficient to ensure the desired completeness as a reliability indicator of the positioning solution will always be a large value, making it unsuitable for practical use.

[0062] Therefore, in this invention, the pseudorange error corresponding to the radio wave environment of the user station 3, which is included in the data received from each GNSS satellite 2 (2a, 2b, etc.), is extracted in real time for each GNSS satellite 2 (2a, 2b, etc.), and this real-time extracted pseudorange error for each GNSS satellite 2 (2a, 2b, etc.) is evaluated using a newly proposed pseudorange error evaluation index. Even if a pseudorange error (of a GNSS satellite) would be rejected under uniform conditions in conventional methods, the pseudorange error of that GNSS satellite is rigorously evaluated in real time, and if the pseudorange error is within an error range determined for each GNSS satellite 2 (2a, 2b, etc.), that GNSS satellite can be used without being rejected, thereby ensuring the number of satellites required for positioning (four or more), thereby solving the above problem. Furthermore, the above problem is solved by calculating a limit value for the multipath error that is necessary and sufficient to ensure the desired completeness from the pseudorange error evaluation index, taking the radio wave environment into account.

[0063] More specifically, first, the pseudorange error corresponding to the radio wave environment of the user station 3, which is included in the data received from each GNSS satellite 2 (2a, 2b, etc.), is extracted in real time for each GNSS satellite 2 (2a, 2b, etc.). The pseudorange error extracted in real time for each GNSS satellite 2 (2a, 2b, etc.) is evaluated using a newly proposed pseudorange error evaluation index.

[0064] In this embodiment, the newly proposed evaluation index for pseudorange errors is a CMC (Code-Minus-Carrier) index that combines at least one of the pseudorange or carrier-smoothing pseudorange with a replica of the carrier phase observation value generated from the geometric change between the user station 3 and the GNSS satellites 2 (2a, 2b, etc.) received by the user station 3.

[0065] Other newly proposed evaluation indices for pseudorange errors include an index based on CMC, an index based on the amount of deviation between carrier-smoothing pseudoranges processed with multiple time constants, an index based on the amount of deviation between changes in pseudorange, changes in carrier-smoothing pseudorange, or changes in carrier phase observation value and changes in the geometric distance between user station 3 and GNSS satellite 2 (2a, 2b, etc.) received by user station 3, and the receiver clock drift, an index based on the difference in multipath error between pseudoranges using multiple frequencies, carrier-smoothing pseudoranges, and carrier phase observation value, and time fluctuations in the autocorrelation results of the received signal. or an index that combines these indices with the time variation of the autocorrelation result of the received signal and the carrier phase observation value, or an index that further uses signals for each constellation in addition to these indices, or an index that further uses signals of different constellations in addition to these indices, or an index that combines these indices with indices of the same constellation, or an index that combines these indices including indices of different constellations, or an index that combines these indices and these indices while also taking the constellation into consideration.

[0066] Using this evaluation index for the pseudorange error, a limit value for the multipath error that is necessary and sufficient to ensure the desired completeness is found for each GNSS satellite 2 (2a, 2b, . . .).

[0067] This multipath error limit value is the limit value of the error range of the range error caused by multipath that reflects the radio wave environment of the user station 3 in real time, and is a value that indicates the error range that is necessary and sufficient to ensure completeness. On the other hand, in the calculation unit 6, the range of range error that is allowable for real-time positioning for each GNSS satellite 2 (2a, 2b, etc.) is determined from the respective observation data, and by making a one-to-one correspondence between the allowable value that defines this error range and the limit value of the multipath error obtained for each GNSS satellite 2 (2a, 2b, etc.), it is possible to test the GNSS satellite, i.e., to determine whether or not the GNSS satellite 2 (2a, 2b, etc.) can be used for positioning calculations of the user station 3.

[0068] By testing the GNSS satellites in this manner, the GNSS satellites 2 (2a, 2b, etc.) to be used in the positioning calculations of the user station 3 are selected, and the positioning calculations of the user station 3 are performed. At the same time, a reliability index for the positioning solution that reflects the radio wave environment of the user station 3 in real time is calculated using the limit value of the multipath error that is necessary and sufficient to ensure the desired completeness, calculated from the evaluation index of the pseudorange error of the selected GNSS satellites 2 (2a, 2b, etc.).

[0069] The satellite signals of the GNSS satellites 2 (2a, 2b, etc.) used when determining the evaluation index of the pseudorange error (step 55) are those of GNSS satellites of the same constellation, i.e., GPS satellite signals in this embodiment, but are not limited to this. The evaluation index of the pseudorange error may also be determined for each constellation using satellite signals of GNSS satellites of other constellations, such as Russia's GLONASS satellites, Japan's Quasi-Zenith Satellites, Europe's Galileo, China's Beidou, and India's GAGAN. Furthermore, rather than determining the evaluation index for each constellation, the evaluation index of the pseudorange error may also be determined by combining signals of GNSS satellites of different constellations, such as GPS satellites and Galileo satellites.

[0070] Furthermore, when performing positioning calculations for the user station 3 (step 57), the positioning calculations for the user station 3 may be performed for each constellation using received data, multipath error limits, and SBAS augmentation information from only GNSS satellites in the same constellation among the selected GNSS satellites, and a positioning solution and its reliability index may be calculated individually for each constellation. In this case, the positioning performance for each constellation may be determined by comparing the reliability indexes of the positioning solutions for each constellation, and constellations with poor positioning performance, i.e., constellations with large values for the reliability index of the positioning solutions, may be identified and tested. The test results for constellations with poor positioning performance may be fed back to the selection of GNSS satellites 2 to be used in the current positioning calculations for the user station 3, or may be used to select GNSS satellites 2 to be used in the next positioning calculations for the user station 3. [Example]

[0071] A second embodiment of the present invention will be described in detail with reference to FIGS. Figures 3 and 4 are diagrams showing the relationship between the evaluation index of the pseudorange error used in vehicle positioning using GNSS of this invention, the multipath error, and its limit value, where (a) is a diagram showing the relationship between the evaluation index of the pseudorange error, the multipath error, and its limit value, and (b) is a diagram showing the probability density function of the multipath error corresponding to a certain magnitude of evaluation index of the pseudorange error (C1 in Figure 3, C in Figure 4) in (a).

[0072] The second embodiment of the present invention is used for vehicle positioning using the GNSS of the first embodiment of the present invention, and is an embodiment that explains a method for determining the limit value of the multipath error for each GNSS satellite that is necessary and sufficient to ensure the desired completeness from the evaluation index of the pseudorange error extracted in real time for each GNSS satellite 2 (2a, 2b, etc.). The same parts as those in the first embodiment are given the same names and numbers, and the description thereof will be omitted.

[0073] A method for determining the limit value of the multipath error for each GNSS satellite 2 (2a, 2b, etc.) that is necessary and sufficient to ensure the desired completeness from the evaluation index of the pseudorange error extracted in real time for each GNSS satellite 2 (2a, 2b, etc.) used in vehicle positioning using GNSS in the first embodiment of this invention will be described based on Figures 3 and 4. In this embodiment, for simplicity of explanation, a case will be described in which an index based on CMC, which is the simplest type of evaluation index, is used as the evaluation index for the pseudorange error.

[0074] First, in this embodiment, the CMC used as an evaluation index of the pseudorange error is obtained by subtracting the carrier phase from the code pseudorange, as shown in Equation 1 and Equation 2. Here, Equation 1 represents the code pseudorange, and Equation 2 represents the carrier phase.

[0075]

number

[0076]

number

[0077] In the above formula 1, P r s is the code pseudorange, ρ r s is the true distance between the GNSS satellite and the receiver, c(δ r -δ s ) is the clock error between the GNSS satellite and the receiver, I r s is the ionospheric delay, T r s is the tropospheric delay, M r s is the multipath error of the code pseudorange, ε s and ε r are other errors caused by the GNSS satellites and the receiver, respectively. Among these, ε s and ε r is small compared to the other terms and can be ignored.

[0078] In the above formula 2, φ r s λ is the carrier phase, m r s is the multipath error of the carrier, N r s is the wavenumber bias, ε s ' and ε r ' are other carrier phase errors caused by the GNSS satellites and the receiver, respectively. Among these, ε s ' and ε r ' is small compared to the other terms and can be ignored.

[0079] As can be seen from Equation 1 and Equation 2 above, most of the terms in Equation 1 and Equation 2 are common. Therefore, when Equation 2 is subtracted from Equation 1 above, i.e., when the carrier phase is subtracted from the code pseudorange, the remaining terms are the ionospheric delay, the multipath error of the code pseudorange, the multipath error of the carrier, and the carrier wave number bias. When multipath error is calculated using this equation where the carrier phase is subtracted from the code pseudorange, the carrier wave number bias term, among the remaining terms in the subtraction equation, cannot accurately evaluate the multipath error because a discontinuity of an integer multiple of the wavelength can occur when a cycle slip occurs. However, by appropriately detecting cycle slips and correcting the wave number bias, the reliability of the multipath error calculation can be improved. Of the remaining terms after subtracting the carrier phase equation from the code pseudorange equation, the carrier wavenumber bias term can be appropriately estimated using the code pseudorange when the radio wave environment is favorable. If a discontinuity in the wavenumber bias occurs when a cycle slip is detected in step 54 of Figure 2, it is corrected and can be eliminated. The ionospheric delay term doubles when the carrier phase equation is subtracted from the code pseudorange equation, but over short periods (several tens of seconds), this is small compared to the multipath error. Furthermore, while Equations 1 and 2 are single-frequency equations, in principle, the ionospheric delay can also be eliminated by using a dual-frequency equation. Regarding multipath error, while the code pseudorange fluctuates by ±m when affected by multipath, the carrier phase only changes by ±5cm (1 / 4 wavelength), even when affected by multipath. Therefore, multipath error can be extracted by subtracting the carrier phase from the code pseudorange.

[0080] Figures 3 and 4 show the relationship between the limit value of the multipath error, which is the evaluation parameter for the multipath error extracted in this way, and the evaluation index for the pseudorange error (CMC in this embodiment). Figure 3 shows the relationship between the evaluation index for the pseudorange error and the multipath error and its limit value when the code is not taken into account, and Figure 4 shows the relationship when the code is taken into account. In Figures 3(a) and 4(a), the vertical axis represents the multipath error, and the horizontal axis represents the evaluation index for the pseudorange error (CMC in this embodiment). In Figures 3(b) and 4(b), the horizontal axis represents the multipath error, and the vertical axis represents the probability density.

[0081] 3 and 4 are schematic diagrams showing the relationship between the results of positioning using the GNSS-based vehicle positioning device of the present invention. FIG. 3 shows the relationship between the evaluation index of pseudorange error and the multipath error and its limit value when the sign is not taken into account, and FIG. 4 shows the relationship when the sign is taken into account. FIGS. 3(a) and 4(a) respectively show the solution of the evaluation index of pseudorange error and the resulting multipath error with a black circle. FIGS. 3(b) and 4(b) respectively show the probability density function of the multipath error corresponding to a certain magnitude of evaluation index of pseudorange error (C1 in FIG. 3, C in FIG. 4) in FIGS. 3(a) and 4(a), and show the relationship between the probability density of the multipath error and its limit value. In this embodiment, the desired completeness is "1-1×10 -7 " or less, and the integral value of the occurrence probability of multipath errors that does not satisfy this desired perfection is represented by the shaded areas in Figures 3(b) and 4(b), respectively.

[0082] As is clear from Figure 3, the desired completeness is 1-1 x 10 -7 " or less, the limit value of the multipath error that satisfies the completeness corresponding to the evaluation index of the pseudorange error C1 becomes E1, and changes as shown in the limit value curve of Figure 3(a) with respect to the evaluation index of the pseudorange error. Also, Figure 4 is a diagram when the sign is taken into consideration as described above, and as is clear from this Figure 4, the multipath error that corresponds to the evaluation index of the pseudorange error C follows a normal distribution and the desired completeness is "1-1 x 10 -7" or less, the limit value of the multipath error that satisfies the completeness is E0±E, and changes as shown in the limit value curve in Figure 4(a) with respect to the evaluation index of the pseudorange error.

[0083] Since there is a relationship between the multipath error and the evaluation index of the pseudorange error (CMC in this embodiment) as shown in Figures 3 and 4, the evaluation index of the pseudorange error can be used to find a limit value that satisfies completeness for the multipath error, which is a range error caused by multipath. [Industrial Applicability]

[0084] Evaluation index of pseudorange error in vehicle positioning using GNSS according to this invention Method for selecting GNSS satellites to be used for positioning calculations The method for calculating the reliability index of the positioning solution can be used for GNSS-based positioning performed in places where the radio wave environment is not ideal, such as on the ground or in harbor areas.

[0085] The vehicle positioning method and device using GNSS according to the present invention can also be used for positioning a moving object using GNSS in places where the radio wave environment is not ideal, such as on the ground or in harbor areas. Such moving objects include not only vehicles, but also ships in harbor areas and aircraft on airport surfaces. [Explanation of symbols]

[0086] 1. Vehicle positioning device using GNSS 2(2a, 2b...) GNSS satellite 3 User Station 4 Antennas 5 Receiver 6 Arithmetic section 7 Display section

Claims

1. A method for selecting GNSS satellites to be used for positioning calculations based on an evaluation index of pseudorange errors used for vehicle positioning using GNSS, in which a positioning solution is calculated using data received from GNSS satellites at a user station, comprising: The evaluation index of the pseudorange error is At least one of a pseudorange or a carrier-smoothing pseudorange; a replica of a carrier phase observation generated from geometric changes between the user station and a GNSS satellite received at the user station; It is a CMC index that combines A method for selecting GNSS satellites to be used for positioning calculations based on an evaluation index of pseudorange errors, characterized by:

2. The evaluation index of the pseudorange error is an index that further combines the autocorrelation result of the received signal and the time fluctuation of the carrier phase observation value.

2. The method for selecting GNSS satellites to be used in positioning calculations based on an evaluation index of pseudorange errors according to claim 1,

3. The evaluation index of the pseudorange error is an index using a signal for each constellation. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index of pseudorange errors according to any one of claims 1 and 2.

4. The evaluation index of the pseudorange error is an index that also uses a signal of a constellation different from the satellite signal of the GNSS satellite used when calculating the evaluation index of the pseudorange error. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index of pseudorange errors according to any one of claims 1 and 2.

5. The evaluation index of the pseudorange error is a combination of the evaluation index of the pseudorange error used in the method of claim 1 and the evaluation index of the pseudorange error used in the method of claim 2, both of which are evaluation indexes of the pseudorange error of the same constellation. A method for selecting GNSS satellites to be used for positioning calculations based on an evaluation index of pseudorange errors, characterized by:

6. The evaluation index of the pseudorange error is a combination of evaluation indexes of pseudorange errors based on the deviation between carrier smoothing pseudoranges processed by a plurality of time constants and evaluation indexes of pseudorange errors of the same constellation.

6. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index of pseudorange errors according to claim 1 or claim 5.

7. The evaluation index of the pseudorange error is a pseudorange error evaluation index obtained by combining evaluation indexes of pseudorange errors of the same constellation, such as a change in pseudorange, a change in carrier smoothing pseudorange, or a pseudorange error evaluation index due to a change in carrier phase observation value, a change in the geometric distance between the user station and the GNSS satellite received by the user station, and a deviation amount from the receiver clock drift. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index for pseudorange errors according to claim 1 or any one of claims 5 and 6.

8. The evaluation index of the pseudorange error is a pseudorange error evaluation index that combines evaluation indexes of pseudorange errors using multiple frequencies, carrier smoothing pseudorange, and pseudorange error using the difference in multipath error of carrier phase observation value with evaluation indexes of pseudorange errors of the same constellation. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index for pseudorange errors according to claim 1 or any one of claims 5 to 7.

9. The evaluation index of the pseudorange error is a pseudorange error evaluation index obtained by combining evaluation indexes of pseudorange errors of the same constellation, which further utilize time fluctuations in the autocorrelation results of the received signal. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index for pseudorange errors according to claim 1 or any one of claims 5 to 8.

10. The evaluation index of the pseudorange error is a combination of the evaluation index of the pseudorange error used in the method of claim 1 and the evaluation index of the pseudorange error used in the method of claim 2, including evaluation indexes of pseudorange errors of different constellations. A method for selecting GNSS satellites to be used for positioning calculations based on an evaluation index of pseudorange errors, characterized by:

11. The evaluation index of the pseudorange error is a combination of the evaluation index of the pseudorange error based on the deviation between carrier smoothing pseudoranges processed by a plurality of time constants, and the evaluation index of the pseudorange error of different constellations.

11. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index of pseudorange errors according to claim 1 or claim 10.

12. The evaluation index of the pseudorange error is a combination of evaluation indexes of pseudorange errors due to a change in pseudorange, a change in carrier smoothing pseudorange, or a change in carrier phase observation value, a change in the geometric distance between the user station and the GNSS satellite received by the user station, and a deviation amount from the receiver clock drift, including evaluation indexes of pseudorange errors of different constellations. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index for pseudorange errors according to claim 1 or any one of claims 10 to 11.

13. The evaluation index of the pseudorange error is a combination of evaluation indexes of pseudorange errors using multiple frequencies, carrier smoothing pseudoranges, and pseudorange error evaluation indexes utilizing the difference in multipath error of carrier phase observation values, including evaluation indexes of pseudorange errors of different constellations. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index for pseudorange errors according to claim 1 or any one of claims 10 to 12, characterized in that:

14. The evaluation index of the pseudorange error is a combination of an evaluation index of the pseudorange error that utilizes the time fluctuation of the autocorrelation result of the received signal and an evaluation index of the pseudorange error of a different constellation. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index of pseudorange errors according to claim 1 or any one of claims 10 to 13.

15. The carrier phase observations are (a) Carrier phase observation value of the received data of the GNSS satellite received by the user station; (b) a replica of the carrier phase observation generated from the geometric change between the user station and the GNSS satellite received at the user station; By comparing the carrier phase observation value with the carrier phase observation value of the received data of the GNSS satellite in which the cycle slip occurred, a cycle slip is detected, and the carrier phase observation value is corrected for the wave number bias of the carrier phase observation value. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index of pseudorange errors according to any one of claims 1 to 14.

16. The carrier phase observations are (a) Carrier phase observation value of the received data of the GNSS satellite received by the user station; (b) Evaluation index of pseudorange error using time fluctuation of autocorrelation result of received signal By combining these, cycle slips can be detected. (c) Carrier phase observation values obtained by correcting the wave number bias of carrier phase observation values of received data from a GNSS satellite in which a cycle slip has occurred, using a replica of the carrier phase observation value generated from geometric changes between the user station and the GNSS satellite received at the user station. A method for selecting GNSS satellites to be used in positioning calculations using an evaluation index of pseudorange errors according to any one of claims 1 to 14.

17. In the reliability index of a positioning solution used for vehicle positioning using GNSS, a positioning solution is calculated using data received from GNSS satellites received by a user station, extracting, in real time for each satellite, an evaluation index of the pseudorange error used in the method according to any one of claims 1 to 16, which is included in the reception data of the GNSS satellite received by the user station and corresponds to the radio wave environment of the user station; A limit value of the multipath error necessary and sufficient to ensure completeness is calculated for each satellite from the evaluation index of the pseudorange error extracted in real time, Calculating the reliability index of the positioning solution that reflects the radio wave environment of the user station in real time from the limit value of the multipath error calculated for each of these satellites. A method for calculating a reliability index of a positioning solution characterized by:

18. A vehicle positioning method using GNSS, which selects a GNSS satellite to be used in a positioning calculation of a user station by testing the GNSS satellite using reception data of the GNSS satellite received by the user station, and calculates a positioning solution and a reliability index of the positioning solution using the reception data of the selected GNSS satellite, extracting, in real time for each satellite, an evaluation index of the pseudorange error used in the method according to any one of claims 1 to 16, which is included in the reception data of the GNSS satellite received by the user station and corresponds to the radio wave environment of the user station; A limit value of the multipath error necessary and sufficient to ensure completeness is calculated for each satellite from the evaluation index of the pseudorange error extracted in real time, By inspecting the GNSS satellites using the limit values of the multipath errors calculated for each of the satellites, the GNSS satellites to be used for the positioning calculation of the user station are selected, and a positioning solution is calculated using the received data of the selected GNSS satellite, and a reliability index of the positioning solution that reflects the radio wave environment of the user station in real time is calculated. A vehicle positioning method using GNSS, characterized by:

19. From the received data of the GNSS satellite received at the user station (a) Carrier phase observation value of reception data of a GNSS satellite received at a user station; (b) a replica of the carrier phase observation generated from the geometric change between the user station and the GNSS satellite received at the user station; and verifying the carrier phase observation value by comparing the cycle slip with the received data of the GNSS satellite in which the detected cycle slip occurred. The method for determining vehicle position using GNSS according to claim 18,

20. From the received data of a GNSS satellite received at a user station (a) Carrier phase observation value of reception data of a GNSS satellite received at a user station; (b) Evaluation index of pseudorange error using time fluctuation of autocorrelation result of received signal By combining these, cycle slips can be detected. (c) correcting the wave number bias of the carrier phase observation value of the received data from the GNSS satellite in which a cycle slip has occurred, using a replica of the carrier phase observation value generated from a geometric change between the user station and the GNSS satellite received at the user station; The method for determining vehicle position using GNSS according to claim 18,

21. Calculating a positioning solution and its reliability index individually for each constellation, and determining constellations with poor positioning performance by comparing the reliability indexes of the positioning solutions for each constellation, and selecting GNSS satellites to be used in the positioning calculation of the user station by inspecting the GNSS satellites of the constellations with poor positioning performance. A vehicle positioning method using GNSS according to any one of claims 18 to 20, characterized in that:

22. A vehicle positioning device using GNSS, comprising: means for selecting a GNSS satellite to be used for positioning calculation of a user station by verifying the GNSS satellite using reception data of the GNSS satellite received by the user station; and means for calculating a positioning solution and a reliability index of the positioning solution using the reception data of the selected GNSS satellite, means for extracting, in real time for each satellite, an evaluation index of a pseudorange error used in the method according to any one of claims 1 to 16, which is included in reception data of a GNSS satellite received by the user station and is in accordance with the radio wave environment of the user station; a means for determining, for each of the satellites, a limit value of the multipath error that is necessary and sufficient to ensure completeness from the evaluation index of the pseudorange error extracted in real time; The system comprises a means for selecting a GNSS satellite to be used for the positioning calculation of a user station by inspecting the GNSS satellite using the limit value of the multipath error calculated for each of the satellites, and for calculating a positioning solution using the received data of the selected GNSS satellite and a reliability index of the positioning solution that reflects the radio wave environment of the user station in real time. A vehicle positioning device using GNSS, characterized by:

23. From the received data of a GNSS satellite received at a user station (a) Carrier phase observation value of reception data of a GNSS satellite received at a user station; (b) a replica of the carrier phase observation generated from the geometric change between the user station and the GNSS satellite received at the user station; and verifying the carrier phase observation value by comparing the cycle slip with the carrier phase observation value of the received data of the GNSS satellite in which the detected cycle slip occurred. The vehicle positioning device using GNSS according to claim 22,

24. From the received data of a GNSS satellite received at a user station (a) Carrier phase observation value of reception data of a GNSS satellite received at a user station; (b) Evaluation index of pseudorange error using time fluctuation of autocorrelation result of received signal By combining these, cycle slips can be detected. (c) further comprising means for correcting a wave number bias of a carrier phase observation value of received data from a GNSS satellite in which a cycle slip has occurred, using a replica of the carrier phase observation value generated from a geometric change between the user station and the GNSS satellite received at the user station. The vehicle positioning device using GNSS according to claim 22,

25. The system further comprises means for calculating a positioning solution and its reliability index individually for each constellation, means for determining a constellation with poor positioning performance by comparing the reliability index of the positioning solution for each constellation, and means for selecting a GNSS satellite to be used for positioning calculation of a user station by inspecting the GNSS satellites of the constellation with poor positioning performance. A vehicle positioning device using GNSS according to any one of claims 22 to 24, characterized in that:

Images