JP2002040128A - Radiolocation method by gps, navigation device, and gps reception device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radiolocation method by GPS which can obtain high positional accuracy. SOLUTION: For example, a point P' is measured at the position of a point P (correct position) by using a radio wave sent from a GPS satellite C. Current dummy range data are C-P". The dummy range data C-P' include errors, e.g. ionosphere delay. Correction range data C-P", which include no error or a very small error can be found, by adding a certain radiolocation correction value C' to the dummy range data C-P'. A radiolocation result calculated by using the correction range data C-P" is a position shown by a point P". This point P" is closer to the correct position shown by the point P than the point P'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a GPS (Global Pos
The present invention relates to a positioning method and a navigation device using a sitioning system (global positioning system).

[0002]

2. Description of the Related Art GPS is a position measurement system developed using a GPS satellite orbiting in the sky to determine in real time the position and moving speed of a moving object such as a car, an aircraft or a ship on the earth. System, these days,
In addition to the positioning by a moving object, the method is widely used in the field of static surveying for measuring the distance and direction between certain points on the earth. When using such a GPS system, a GPS receiver for receiving radio waves transmitted from GPS satellites is used.

FIG. 7 is an explanatory diagram showing a schematic configuration of a generally used GPS system. As shown in FIG. 7, 1.557542 GHz spread spectrum radio waves are transmitted from the GPS satellite 300. The transmitted radio wave is received by the antenna unit 311 of the GPS receiver 310 after a propagation time according to the distance. The radio wave received by the antenna unit 311 is down-converted to a predetermined intermediate frequency by the RF unit 312 and enters the signal synchronous demodulation unit 313. After that, the signal synchronous demodulation unit 3
At 13, the radio wave is despread, and the data is demodulated. The demodulated data is used by the signal processing unit 314 for positioning calculation. Thus, the radio wave transmitted from the GPS satellite 300 is received by the GPS receiver 310,
Positioning calculation is performed.

[0004] Radio waves from GPS satellites that reach measurement points on the earth contain errors. That is, an error mainly due to a radio wave propagation delay caused by passing through the ionosphere is included. Since this error is changing in real time, G
If positioning calculations are performed using only radio waves from PS satellites,
The positioning accuracy is reduced.

[0005]

DGPS (Differential GPS) is known as a method for improving positioning accuracy on the premise that radio waves from GPS satellites have errors. This DGPS receives radio waves from GPS satellites at fixed reference stations in various parts of Japan, and the fixed reference stations
The PS positioning calculation is performed, and the correction value of the range data is calculated from the position error generated there. Then, this correction value is
A mobile unit provided with M multiplex broadcasting and receiving this correction value
This correction value is considered when performing the PS positioning calculation. Therefore, in order to use DGPS, an FM radio wave receiver and a demodulator of a received signal are required.

A car navigation device is a typical example using a GPS system. The car navigation device can perform positioning using the GPS system, but cannot know the road condition that changes every moment. Therefore, a system for providing road traffic information such as traffic congestion information and traffic regulations using a wireless communication system has been operated. This system is based on VICS (Vehicle Inform
Road and traffic information is provided by FM multiplex broadcasting. Therefore, a car navigation device that can use VICS includes an FM radio receiver and a demodulator of a received signal.

As described above, a car navigation device that can use VICS is equipped with an FM radio wave receiver and a demodulator of a received signal, so that it is possible to use DGPS. However, the frequency differs between FM multiplex broadcasting that provides a correction value by DGPS and FM multiplex broadcasting that provides VICS road traffic information. Therefore, in order to receive the DGPS FM radio wave and the VICS FM broadcast at all times, either two FM radio receivers are used, or one FM radio receiver uses the DGPS FM radio receiver.
It is conceivable to alternately receive radio waves and FM broadcasts of VICS. Due to cost considerations, the latter method is actually adopted. Therefore, DGPS cannot be used while VICS is used, and high positional accuracy cannot be maintained. In other words, if the positioning accuracy can be improved without using DGPS,
There is no problem with VICS usage.

Further, if the car is located behind a building or in a tunnel, the car navigation device cannot receive radio waves from GPS satellites, and the car navigation system may not be able to receive GPS signals while driving.
Radio waves from satellites cannot be received continuously. Then, the navigation device using the GPS has a basic problem that the positioning calculation is intermittently disabled and the positioning accuracy is reduced. Therefore, an object of the present invention is to provide a GPS positioning method, a navigation device, and a GPS receiver capable of obtaining high position accuracy.

[0009]

In a conventional navigation device using a GPS system, an error is included in a position measured using a radio wave from a GPS satellite, and the position is determined to be a position other than a road. May be. Therefore, most commonly, the final current position is obtained using a correction method called map matching. The map matching is a technique of comparing a traveling locus of an automobile with road map data to find a location where the two are most likely to coincide with each other, and correcting a measurement position. That is, the information on the position corrected by the map matching can be said to be position information with higher accuracy than the position measured using the radio waves from the GPS satellites. Therefore, the present inventor regards the position corrected by the map matching as a DGPS reference station, obtains the range data between the corrected position and the GPS satellite used for the positioning calculation, and obtains the GPS data.
By comparing the position calculated using the radio wave from the satellite with the range data between the GPS satellite, the error of the radio wave from the GPS satellite was confirmed, and attention was paid to using this error information as a correction value.

Therefore, the GPS positioning method of the present invention measures a position using radio waves transmitted from a GPS satellite, performs a correction process on the measured position, sets a corrected position, and performs measurement of the position. The correction range data is obtained from the used GPS satellite and the correction position, the error included in the radio wave transmitted from the GPS satellite used for the measurement of the position is obtained based on the correction range data, and the radio wave from the GPS satellite is obtained. Is used to calculate a positioning result based on the position measured using and the error. G of the present invention
According to the positioning method using the PS, the correction range data is acquired from the GPS satellite used for the position measurement and the correction position, and the error included in the radio wave from the GPS satellite used for the measurement based on the correction range data is obtained. Ask. Since the position is measured in consideration of the error, the obtained positioning result has high accuracy. In particular, according to the positioning method of the present invention, even if the radio wave from the GPS satellite is interrupted once, if the error information is held, the position can be measured in consideration of the error information. High-accuracy positioning can be realized early. In a navigation device using DGPS and VICS, D
If the positioning method of the present invention is applied to a time zone where GPS is not used, positioning with higher accuracy than in the past can be maintained.

The present invention provides a navigation device to which the above-described GPS positioning method is applied. That is, the navigation device of the present invention comprises a correction means for obtaining a correction position for a measurement position using radio waves transmitted from a GPS satellite, and a first range data for calculating pseudo range data from the GPS satellite to the measured position. Calculating means;
Second range data calculation means for calculating correction range data from the GPS satellite to the correction position; positioning correction value calculation means for calculating a positioning correction value that is a difference between the pseudo range data and the correction range data; And a positioning calculation means for calculating a positioning result using the positioning correction value. The navigation device according to the present invention includes a correction unit that calculates a correction position for a position measured using radio waves transmitted from a GPS satellite.
Since the position measured using the radio wave transmitted from the GPS satellite includes an error in the radio wave from the GPS satellite,
There is considerable deviation from the actual position. Therefore, a correction process is performed on this position. As this correction processing, the map matching processing currently performed in the navigation device is preferable. The map matching process is a technology that presupposes that an automobile runs on a road, compares a traveling locus of the automobile with road map data, finds a location where the two are most coincident, and corrects the measured position. . Therefore, a position obtained by performing the map matching process is closer to a correct position than a position measured using radio waves from GPS satellites. Although the map matching process has been described as one of the methods for obtaining the correction position, the present invention is not limited to this. As another method, a correction process can be performed based on the change data of the speed and the direction of the vehicle. This data is used in well-known autonomous navigation, and is an effective technique in a navigation device that uses autonomous navigation together.

The navigation device according to the present invention includes first and second range data calculating means. The first range data calculating means calculates pseudo range data from a GPS satellite to the measured position. This pseudo range data is information including an error such as ionospheric delay. On the other hand, the second range data calculation means calculates correction range data from the GPS satellite to the correction position. Even if the correction range data does not include an error or does include an error, the correction range data is smaller than the pseudo range data. The range data is defined by the distance or the propagation time of the radio wave as described above. The pseudo range data is information including an error factor such as ionospheric delay, and the correction range data is smaller than the pseudo range data even if the correction range data does not include the error factor. Therefore, by comparing the pseudo range data and the correction range data, it is possible to recognize an error for the GPS satellite. Therefore, the navigation device of the present invention includes a positioning correction value calculation unit. Then, the positioning correction value calculating means obtains a difference between the pseudo range data and the correction range data, and sets the difference as a positioning correction value. This positioning correction value can be regarded as an error. The navigation device of the present invention includes a positioning calculation unit that calculates a positioning result using the positioning correction value. For example, if the next time a radio wave is received from a GPS satellite, the result measured using this radio wave contains an error,
By adding (or subtracting) the positioning correction value, it is possible to obtain a highly accurate positioning result excluding the error.

Incidentally, the positioning correction value is not always effective. The positioning correction value can be said to be information on an error. Since the cause of the error depends on the natural world such as the ionospheric delay, it should be considered that the error always fluctuates. Therefore, as time elapses after obtaining the positioning correction value, the positioning correction value loses accuracy.
Therefore, in the navigation device of the present invention, it is desirable that the positioning correction value calculation means calculates the positioning correction value and determines whether the positioning correction value is valid. As is clear from the above description, whether or not the positioning correction value is valid is determined based on the time from when the positioning correction value is obtained as a basic criterion. Then, when the positioning correction value calculating means determines that the positioning correction value is valid, the positioning calculating means calculates a positioning result using the positioning correction value. Validity of positioning correction value
As described above, the basic criterion of invalidity is the elapsed time from the determination of the positioning correction value, but it is determined from the number of GPS satellites used for measurement and the arrangement of GPS satellites used for measurement. Accuracy Degradation Index (DOP)
ecision) value) can be an additional criterion. That is, in the navigation device according to the present invention, the positioning correction value calculating means includes an accuracy determined from a time after the correcting means obtains the corrected position, the number of GPS satellites used for measurement, and an arrangement of the GPS satellites used for measurement. It can be determined whether the positioning correction value is valid based on the deterioration index. Since the number of GPS satellites and the DOP value used for the measurement affect the accuracy of the measurement, they are to be reflected in the calculation of the positioning correction value. Incidentally, the greater the number of GPS satellites used for the measurement and the smaller the DOP value, the higher the accuracy of the measurement.

In the navigation device of the present invention, in order to further improve the accuracy of the positioning result calculated using the positioning correction value, it is desirable that the corrected position has a predetermined accuracy. Therefore, the navigation device of the present invention includes a correction position determination unit that determines whether the correction position has a predetermined accuracy, and the positioning calculation unit determines that the correction position has a predetermined accuracy. When it is determined, it is desirable to calculate the position. Whether or not the corrected position has a predetermined accuracy is determined by observing the coincidence between the track on which the moving object equipped with the navigation device, for example, the car has moved, and the road on the map data after obtaining the corrected position. Can be determined. For example, if the vehicle does not deviate from the road even after repeated right and left turns while traveling a predetermined distance, it can be said that the position has predetermined accuracy. The moving distance and the number of right / left turns are determined as appropriate and are not limiting elements of the present invention.

Further, in the navigation device of the present invention, the positioning correction value can be adjusted and used. As described above, the error has a property that varies with time. Therefore, the positioning correction value can be appropriately adjusted according to the passage of time. In addition, the number of GPS satellites and the DOP value used for measurement can be used as additional adjustment factors. The navigation device of the present invention includes DGPS receiving means for performing position correction by DGPS,
The positioning calculation unit can calculate a positioning result using the positioning correction value when the position measurement by the DGPS receiving unit is not performed. When DGPS cannot be used because FM multiplex broadcasting for VICS is received, a positioning result can be calculated using the positioning correction value, so that high-precision positioning can be maintained.

The present invention further comprises a correcting means for performing a map matching process on a position O 'measured using radio waves from a GPS satellite to obtain a corrected position O ",
First calculating means for calculating a distance (A-O ') from the position A of the satellite to the position O'; and a distance (A-O ") from the position A of the GPS satellite to the correction position O" The second to calculate
And a third calculating means for calculating (A-O '')-(A-O '). (A-O ")-(A-O ') is GP
It can be said that the error information is included in the radio wave transmitted from the S satellite. Therefore, by using this information, it is possible to contribute to improvement of the measurement position accuracy in the navigation device.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 is a functional block diagram showing the entire configuration of the car navigation device according to the present embodiment. FIG. 2 is a diagram for explaining the information (data) transfer relationship between the blocks in FIG. As shown in FIG. 1, a car navigation device 1 according to the present embodiment
S receiving unit 10, receiving satellite control unit 30, positioning calculation unit 40,
It includes a movement trajectory calculation unit 50, a map matching unit 60, a display control unit 70, a storage control unit 80, and an autonomous navigation sensor 90. The car navigation device 1 is installed in a vehicle, which is a moving body.

In FIG. 1 and FIG.
0 is provided with a GPS antenna 11 for receiving radio waves from GPS satellites. The GPS receiver 10 includes a plurality of GPS receivers that can be received by a car via a GPS antenna 11
Receives radio waves from satellites. In the case of three-dimensional positioning with respect to latitude, longitude and altitude, four radio waves are received from three GPS satellites, and in the case of two-dimensional positioning with respect to latitude and longitude, radio waves are received from three GPS satellites. The GPS receiver 10 processes radio waves received via the GPS antenna 11 and generates distance information, orbit information, and reception state information for each of the GPS satellites to be received. Here, the distance information refers to a calculated distance from the GPS satellite to the car navigation device 1. The calculated distance is a value including an error due to the ionosphere or the like, and is called pseudo range data in the present invention.
In the present invention, the GPS receiver 10 constitutes a first range data calculator. This pseudo range data is output to the positioning calculation unit 40 as shown in FIG. The orbit information includes information on the position of each GPS satellite constituting the GPS and the GPS target to be received.
Contains detailed satellite orbit information. This orbit information is
Output to the receiving satellite control unit 30. The reception state information is information indicating whether or not radio waves from GPS satellites can be received, and is output to the reception satellite control unit 30.

The receiving satellite control unit 30 selects a GPS satellite used when the positioning calculation unit 40 calculates a positioning. The receiving satellite control unit 30 calculates the arrangement of each GPS satellite based on the orbit information of each GPS satellite output from the GPS receiving unit 10 and the information on the current position of the vehicle. The current position of the vehicle can use the positioning result calculated by the positioning calculation unit 40. Next, the receiving satellite control unit 30 obtains a combination of GPS satellites capable of performing positioning calculation based on the reception state information of each GPS satellite, and further calculates a DOP value for each combination of GPS satellites based on the arrangement of each GPS satellite. I do. The DOP value is called an accuracy deterioration index, and is an index indicating the accuracy of the positioning result calculated by the positioning calculation unit 40. The accuracy of the positioning result increases as the combination of the GPS satellites having a small DOP value is used. A combination of GPS satellites for positioning calculation is selected based on the above DOP value. This selection result is output to the positioning calculation unit 40.

The positioning calculation unit 40 solves a predetermined simultaneous equation based on the pseudo-range data acquired from the GPS receiving unit 10 for each of the GPS satellites constituting the combination selected by the receiving satellite control unit 30 to perform car navigation. The position of the device 1 is calculated. This measurement position is output to the movement trajectory calculation unit 50. Also, the positioning calculation unit 40
Acquires a correction position as a result of map matching from a map matching unit 60 described later. Each GP constituting the combination selected by the receiving satellite control unit 30
For the S satellite, correction range data is calculated from the result of the map matching. That is, correction range data as a distance between the position of the vehicle corrected by the map matching and each GPS satellite constituting the combination selected by the receiving satellite control unit 30 is calculated. Therefore, the positioning calculator 40 constitutes a second range data calculator in the present invention. Next, the positioning calculation unit 40 determines whether the GPS
The difference between the pseudo range data output from 0 and the correction range data is obtained. This difference is referred to as a positioning correction value, but can be regarded as an error from the GPS satellite to the vehicle. Therefore, the positioning calculation unit 40
In the present invention, a positioning correction value calculating unit is configured. In addition,
The positioning correction value is stored in the positioning calculation unit 40, and has an expiration date. This is because the error factor changes over time. The positioning calculation unit 40 also has a function of correcting the pseudo range data using the positioning correction value. The position of the car navigation device 1 is calculated by solving a predetermined simultaneous equation based on the corrected range data.
The calculated positioning result is output to the movement trajectory calculation unit 50.

The trajectory calculator 50 determines the trajectory of the vehicle equipped with the car navigation device 1 based on the measured position or the positioning result obtained by the positioning calculator 40. The obtained movement trajectory is output to the map matching unit 60.
The map matching unit 60 performs map matching based on the moving trajectory output from the moving trajectory calculation unit 50 and the road map data, and calculates the current position of the car navigation device 1. Here, as described above, the map matching is a method of comparing a travel locus of an automobile with road map data to determine a location where the two are most likely to match, and correcting a positioning calculation result. Automobile technology is based on the premise of traveling on roads. In the present embodiment, a correction position A for a measurement position and a correction position B for a positioning result
Are generated. The corrected position A is used to calculate a positioning correction value, and the corrected position B is final positioning information. The road map data is stored in, for example, a DVD (Digital Video / Versatile Drive) as an external storage medium, and provided to the map matching unit 60 via a DVD drive 81 connected to the storage control unit 80.

The corrected position A calculated by the map matching unit 60 is output to the positioning calculation unit 40. The correction position B is output to the display control unit 70 and is output to an LCD (Liquid Crystal
Display). The correction position B is also output to the receiving satellite control unit 30 and becomes information for satellite selection. The autonomous navigation sensor 90 detects a traveling speed and an angular velocity of an automobile equipped with the car navigation device 1. As the autonomous navigation sensor 90, a gyro sensor is generally used. Autonomous navigation is a method in which the current position is calculated by the positioning calculation unit 40, and thereafter, the current position is specified by adding the speed and angular velocity (azimuth) obtained by the autonomous navigation sensor 90, that is, the movement of the car. By combining the positioning result of the positioning calculation unit 40 and the positioning result by the autonomous navigation, it is possible to realize more accurate positioning. Further, the change data of the speed and the azimuth can be used for calculating the correction position together with or instead of the above-described map matching.

FIGS. 3 and 4 are conceptual diagrams for explaining a positioning correction value calculating method and a positioning method in the positioning calculating section 40. FIG. In FIG. 3, the car navigation device 1
Is assumed to have received radio waves from GPS satellites A to D at point O (correct position). Note that the GPS satellites A to D
Are points A to D. At this time, due to various error factors including ionospheric delay, the measurement position is at the point O ′.
Became. It is assumed that a point O ″ (correction position A) is obtained by performing a map matching process on the measurement position. Then, this point O ″ is assumed to be a correct position (point O). Here, the processing for calculating the point O ′ includes:
The pseudo range data AO 'including an error from the point A (GPS satellite A) to the measurement point was used. The pseudo range data A-O 'is the distance from the GPS satellite A to the measurement point (or the propagation time of the radio wave). However, the correction range data A-O "between the point O" and the point A (GPS satellite A) corrected by the map matching is small even if it does not include an error. Pseudo range data A
−O ′, the difference between the correction range data A−O ″ is A ′,
The positioning correction value for the GPS satellite A is obtained by the following equation. A ′ = (A−O ″) − (A−O ′) GPS satellite B
Similarly, the pseudo range data B-O, C-
O, DO, and a positioning correction value for each of the GPS satellites B, C, and D are obtained by the following equation.
0 is stored. B ′ = (BO ″) − (BO ′) C ′ = (CO ″) − (CO ′) D ′ = (DO ″) − (DO ′) )

When a new positioning calculation is performed, by adding the above-mentioned positioning correction value to the newly obtained pseudo-range data, a positioning result closer to a correct position can be obtained by canceling the error. For example, as shown in FIG. 4, at the position of point P (correct position), the GPS satellite A
To D are received. FIG. 4 shows only the GPS satellite C for easy understanding.
A measurement position using radio waves received from the GPS satellites A to D is defined as a point P ′. The pseudo range data at this time is AP ′ ~
DP ′. These pseudo range data AP ′ to D−
P ′ includes an error including an ionospheric delay.
Therefore, as shown in the following equation, this range data A-
When the positioning correction values A ′ to D ′ stored in the positioning calculation unit 40 are added to P ′ to DP ′, minute correction range data AP ″ to DP can be obtained even if they do not include or include an error. ''. AP ″ = (AP ′) + A ′, BP ″ = (BP ′)
+ B ′ CP ″ = (CP ′) + C ′, DP ″ = (DP ′)
By using the correction range data AP ″ to DP ″ equal to or greater than + D ′, the calculated positioning result is the position indicated by the point P ″ in FIG. This point P ″ is closer to the correct position indicated by the point P than the point P ′. By performing a map matching process on the point P ′, the point P can be obtained.

FIG. 5 is a flowchart showing the operation from the start to the end of GPS positioning according to the present embodiment. In FIG. 5, when the GPS positioning is started, the positioning calculation unit 4
It is determined whether the positioning correction value stored in 0 is valid (S101). As described above, the positioning correction value has an expiration date. This expiration date also takes into account the number of GPS satellites used for measurement and the DOP value. In the present embodiment, the number of GPS satellites used for measurement is 4
The expiration date when the DOP value is 3 is 30 seconds. That is, when the number of GPS satellites used for measurement is four and the DOP value is 3, the positioning correction value is valid within 30 seconds after obtaining the positioning correction value, but becomes invalid after 30 seconds. . When the number of GPS satellites and the DOP value change with reference to the number 4 of GPS satellites and the DOP value 3, the expiration date also changes. Assuming that the expiration date is Te, the number of GPS satellites used for positioning is Sn, and the DOP value is Dn, the expiration date Te is obtained by the following equation. Te (seconds) = 30 (seconds) × (Sn / 4) × (3 / Dn) For example, if the number of GPS satellites used for positioning becomes 5 while the DOP value remains 3, the expiration date Te is given by the following equation. By 3
7.5 seconds. Te = 30 (seconds) × (5/4) × (3/3) = 37.5
(Second) Further, assuming that the DOP value has changed to 5, the expiration date Te is 22.5 seconds according to the following equation. Te = 30 (seconds) × (5/4) × (3/5) = 22.5
(Seconds)

When the positioning correction value is determined to be valid,
The positioning result is calculated by correcting the pseudo range data using the positioning correction value (S103). This calculation method is shown in FIG.
4 and FIG. Here, the positioning correction value can be appropriately adjusted according to the number of GPS satellites used for the measurement and the DOP value. For example, when the number of GPS satellites used for measurement is four or more and the DOP value is three or less, the number of GPS satellites used for positioning and the DOP value are used on the basis that the positioning correction value is used as it is, that is, 100% is used. , The positioning correction value can be adjusted. If the number of GPS satellites used for positioning is three and the DOP value is 3 or less, 100 (%) × 3 ÷ 4 = 75%. If the DOP value at this time is 5, 75% × 3 ÷ 5 = 45. %. If the positioning correction value is not valid, the positioning result is calculated without correcting the pseudo range data (S102). That is, the result of performing the map matching process on the pseudo range data is the positioning result.

At this point, the calculation of the positioning result, that is, the preceding positioning is completed, and the process of obtaining a positioning correction value for a new positioning is performed after S104. When the preceding positioning is completed, a radio wave from a GPS satellite is received for the next positioning to calculate pseudo range data (S104).
G because the car is located behind a building or in a tunnel
If the radio wave from the PS satellite cannot be received, the pseudo range data cannot be calculated, so that the GPS positioning is terminated without performing the subsequent processing, or
Return to 1.

After calculating the pseudo range data, the map matching process is performed as described above. As a result of performing the map matching process, if the position of the positioning point can be corrected on the nearby road (S105), it is determined whether or not the accuracy of the vehicle position is equal to or more than the reference value (S1).
06). If the position of the positioning point cannot be corrected on the nearby road, the GPS positioning is terminated without performing the subsequent processing, or the process returns to S101. The determination as to whether or not the accuracy of the vehicle position is equal to or higher than the reference value is made based on whether or not the following two conditions are satisfied. Condition 1: 45 to 13 with respect to the traveling direction while traveling 1 km
The 5 ° right / left turn was repeated twice or more. Condition 2: The vehicle did not deviate from the road due to map matching during the traveling of Condition 1. The reason why the accuracy of the own vehicle position is determined as described above is that the accuracy of the own vehicle position affects the accuracy of the positioning correction value. The reason why the accuracy of the vehicle position is determined based on the above two conditions is as follows. In other words, if the vehicle only travels straight, it is not possible to determine that the position in the direction of extension of the road is accurate, although it is certain that the vehicle is located on the road. If the vehicle does not deviate from the road even after repeated right and left turns, the position can be said to be highly accurate. However, the above condition is merely an example, and cannot be a basis for limiting the present invention. If the accuracy of the own vehicle position is determined to be equal to or higher than the reference value, pseudo range data between each GPS satellite and the own vehicle position is calculated, and a difference from the correction range data, that is, a positioning correction value is obtained (S107). This positioning correction value is stored in the positioning calculation unit 4.
0 is stored.

In the above embodiment, the car navigation apparatus 1 having no DGPS receiving function has been described. However, the present invention may be applied to a navigation apparatus 1 having a DGPS receiving unit 20 as shown in FIG. . In the car navigation device 1 of FIG. 6, the same parts as those of the car navigation device 1 shown in FIG. 1 are denoted by the same reference numerals. The DGPS receiver 20 includes a DGPS antenna 21 for receiving radio waves transmitted from a DGPS reference station. The reference station provides error information obtained by comparing the position of the reference station with position information from a GPS satellite to be received, for example, by FM multiplex broadcasting. Therefore, the DGPS receiving unit 20 includes the FM radio wave receiver and the demodulator of the received signal.
The error information received by the S receiving unit 20 is
Output for 0. The positioning calculation unit 40 calculates a positioning result using this information. Since the DGPS receiving unit 20 includes the FM radio wave receiver, the DGPS receiving unit 20 can also receive the FM multiplex broadcast for VICS. Therefore,
DGPS does not function while the DGPS receiving unit 20 is receiving FM multiplex broadcasting about VICS. However, according to the present embodiment, it is possible to execute highly accurate positioning calculation by obtaining the positioning correction value while the DGPS does not function. Further, the DGPS can be made to function at an arbitrary timing, and the positioning can be calculated using the positioning correction value according to the timing.

[0030]

As described above, according to the present invention,
Correction range data is obtained from the GPS satellite used for position measurement and the correction position, and an error included in a radio wave from the GPS satellite used for measurement is obtained based on the correction range data. Since the position is measured in consideration of the error, the obtained measurement result has high accuracy. In particular, according to the positioning method of the present invention, even if the radio wave from the GPS satellite is interrupted once, if the error information is held, the position can be measured in consideration of the error information. High-accuracy positioning can be realized early. Also, in a navigation device using DGPS and VICS, if the positioning method of the present invention is applied during a time period when DGPS is not used, positioning with higher accuracy than before can be maintained.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a car navigation device 1 according to the present embodiment.

FIG. 2 is a diagram illustrating an information transfer relationship between functional blocks of the car navigation device 1 according to the present embodiment.

FIG. 3 is a conceptual diagram illustrating a positioning correction value calculation method and a positioning method in a positioning calculation unit 40 of the car navigation device 1 according to the present embodiment.

FIG. 4 is a conceptual diagram illustrating a positioning correction value calculation method and a positioning method in a positioning calculation unit 40 of the car navigation device 1 according to the present embodiment.

FIG. 5 is a diagram illustrating a G according to the present embodiment.
It is a flowchart which shows operation | movement from PS positioning start to completion | finish.

FIG. 6 is a functional block diagram showing a modified example of the car navigation device 1 of the present embodiment.

FIG. 7 is a diagram showing a schematic configuration of a GPS system.

[Explanation of symbols]

10 GPS receiver, 11 GPS antenna, 20 D
GPS receiving unit, 21: DGPS antenna, 30: receiving satellite control unit, 40: positioning calculation unit, 50: moving trajectory calculation unit,
60: Map matching unit, 70: Display control unit, 71:
Display unit, 80: storage control unit, 81: DVD drive, 9
0… Autonomous navigation sensor

Continued on the front page F term (reference) 2F029 AA02 AB01 AB07 AB09 AC02 AC08 AC14 AC19 AD01 5H180 AA01 BB13 CC12 EE18 FF04 FF05 FF07 FF12 FF13 FF22 FF27 5J062 AA03 BB01 BB02 BB03 CC07 DD24 EE04 HH07

Claims (8)

[Claims] 1. A position is measured using a radio wave transmitted from a GPS satellite, a correction process is performed on the measured position to set a correction position, and the GPS satellite used for the position measurement and the correction are set. The correction range data is obtained from the position, the error included in the radio wave transmitted from the GPS satellite used for the position measurement is obtained based on the correction range data, and the position measured using the radio wave from the GPS satellite is calculated. GP for calculating a positioning result based on the error
Positioning method by S. 2. A correction means for obtaining a correction position for a position measured using radio waves transmitted from a GPS satellite, and a first range data calculation means for calculating pseudo-range data from the GPS satellite to the measured position. Second range data calculating means for calculating correction range data from the GPS satellite to the correction position; positioning correction value calculation for calculating a positioning correction value that is a difference between the pseudo range data and the correction range data And a positioning calculating means for calculating a positioning result using the positioning correction value. 3. The positioning correction value calculating means includes: a time from when the correcting means obtains a corrected position;
It is determined whether or not the positioning correction value is valid based on the accuracy deterioration index determined from the number of satellites and the arrangement of the GPS satellites used for the measurement, and the positioning calculation unit determines that the positioning correction value is valid. The navigation device according to claim 2, wherein a positioning result is calculated using the positioning correction value in the case. 4. A correction position determining means for determining whether or not the corrected position has a predetermined accuracy, wherein the positioning calculating means has the corrected position having a predetermined accuracy in the corrected position determining means. 4. A positioning result is calculated when it is determined that the positioning is performed.
The navigation device according to claim 1. 5. The positioning calculation means, based on a time from when the correction means obtains the corrected position, the number of GPS satellites used for measurement, and an accuracy deterioration index determined from the arrangement of the GPS satellites used for measurement, The navigation device according to claim 2, wherein the positioning correction value is adjusted. 6. DGPS receiving means for performing position correction by DGPS, wherein said positioning calculation means calculates a positioning result using said positioning correction value when not performing position measurement by said DGPS receiving means. The navigation device according to any one of claims 2 to 5, wherein 7. The correction method according to claim 2, wherein the correction means performs correction processing based on road map data or performs correction processing based on speed and azimuth change data. A navigation device as described. 8. A correction means for performing a map matching process on a position O ′ measured using radio waves transmitted from a GPS satellite to obtain a correction position O ″, and a distance from the position A of the GPS satellite to the position O ′. First calculating means for calculating (A-O '); second calculating means for calculating the distance (A-O ") from the position A of the GPS satellite to the correction position O"; −O ″) − (A−O ′), and a third calculating unit.