JP2003279362A - Vehicle position correction device and judging method for reliability of positioning by gps - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means for judging whether the state of positioning by GPS is good or bad, and to appropriately perform position correction by the GPS according to its judgment result. <P>SOLUTION: According to the magnitude of difference between a travel distance Ltrace for a certain section by self-contained navigation obtained from a self-contained navigation center, and the distance Lgps between positioning points of the GPS for the same section obtained from a GPS receiver, the reliability of position data obtained from the GPS receiver is judged. A threshold distance value being a comparison reference for deciding whether or not position correction by the GPS is to be performed, when map matching by self-contained navigation becomes impossible, is varied according to the judgment result. When the state of positioning is bad, the threshold distance value is set larger to make it difficult to be influenced by a wrong point of positioning by the GPS. When the state of positioning is good, the threshold distance value is set smaller to facilitate position correction to a correct point of positioning by the GPS. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle position correcting device and a GPS positioning reliability determining method for a navigation system, and more particularly to a positioning function by an autonomous navigation sensor including a distance sensor and an angle sensor, and a GPS (Global Pos.
The present invention relates to a vehicle position correction device for a navigation system having a positioning function by a receiver and a GPS positioning reliability determination method applied to the device.

[0002]

2. Description of the Related Art Generally, a vehicle-mounted navigation device that guides a vehicle so that a driver can easily reach a desired destination can store map data corresponding to the current position of the vehicle in a CD-ROM or a CD-ROM. It is read from a recording medium such as a DVD-ROM and displayed on the screen. In addition, a vehicle position mark indicating the vehicle position is displayed at a predetermined position on the screen in an overlapping manner. Then, as the current position changes due to the movement of the vehicle, the vehicle position mark is moved on the screen, or the vehicle position mark is fixed at a predetermined position on the screen and the map data in the vicinity thereof is scrolled, It makes it possible to see at a glance where the vehicle is currently traveling.

In this type of navigation device, it is essential to measure the current position of the vehicle. For this reason, a measurement method (self-contained navigation) for measuring the relative position of the vehicle using a distance sensor and an angle sensor mounted on the vehicle and an n-dimensional positioning process by receiving radio waves sent from a plurality of GPS satellites The measurement method (satellite navigation) for measuring the absolute position of is being put to practical use.

The vehicle position measurement by self-contained navigation can measure the vehicle position at a relatively low cost, but there is a problem that the position measurement cannot be performed with high accuracy, and correction processing such as map matching processing is required. That is, in self-contained navigation, errors accumulate as the vehicle travels, and the vehicle position deviates from the road. Therefore, the vehicle position is collated with the road data by the map matching process and corrected on the road. Various map matching methods have been proposed. For example, there is a method in which a traveling locus (position and direction for each predetermined traveling distance) is stored, a road on the map having the same shape as the traveling locus is obtained, and a vehicle position mark is map-matched to a point on the road. There is also a map matching method using a projection method.

FIG. 9 is a diagram for explaining map matching by the projection method. In FIG. 9, it is assumed that the vehicle position is at the point P _i-1 (X _i-1 , Y _i-1 ) and the vehicle direction is θ _i-1 . If the relative azimuth when traveling a certain distance L ₀ (for example, 5 m) from the point P _i−1 is Δθ _i , it is the point P _i ′ (X _i ′, Y _i ′) of the vehicle position after traveling by self-contained navigation. , The point P
The vehicle direction θ _i at _i ′ is calculated by the following equation. θ _i = θ _i-1 + Δθ _i X _i '= X _i-1 + L ₀ · cos θ _i Y _i ' = Y _i-1 + L ₀ · sin θ _i

At this time, (a) a link from which a perpendicular can be drawn down from the point P _i ′ (a point where a plurality of roads intersect such as an intersection or a branch is a node, and a straight line corresponding to a road or a lane connecting the nodes is a straight line). (Hereinafter referred to as a link), the angle between the vehicle direction θ _i at the point P _i 'and the link is within a fixed value, and
A line whose length from the point P _i 'to the link is within a certain distance is searched for. Here, the link LK _a1 (direction line connecting the nodes N _a0 and N _a1 ) of the direction θ _a1 on the road RD _a
And a link LK _b1 (node N with direction θ _b1 on road RD _b
A straight line connecting _b0 and _Nb1 ).

Next, (b) point P_i'Link from LK_a1, L
K_b1Vertical line RL_ia, RL_ibSeeking the length of, short
This link is used as a matching candidate. Link L here
K_a1Becomes (c) And point P_i-1And point P_i'Running with
Line trajectory SH_iThe vertical line RL_iaPoint P in the direction of_i-1Is the link L
K_a1On (or link LK_a1Until you reach (on the extension line)
Move line, point P_i-1, Point P_i'Movement point PT_i-1, PT_i'
Ask for. (d) Finally, the point PT_i-1Centered on the point P
T_i'Is the link LK_a1On (or link LK_a1An extension of
The moving point is obtained by rotating and moving until
Correct vehicle position P _i(X_i, Y_i). In addition, modified car
Both positions P_iThe vehicle direction at is θ_iWill be left as it is.

By the way, in the self-contained navigation, when the error becomes large and the vehicle position largely deviates from the road, the vehicle position cannot be map-matched to the actual current position on the road. That is, the map matching method based on the traveling locus cannot find a road having the same shape as the running locus, and the map matching method based on the projection method cannot find a road satisfying the matching condition. When map matching becomes impossible like this,
Navigation does not make sense, you have to stop the car, position the vehicle position mark at the actual vehicle position on the map and restart the navigation. However, such a method has extremely poor operation performance.

Therefore, when a GPS receiver is incorporated in a self-contained navigation system and map matching becomes impossible, position data obtained from the GPS receiver
Using (GPS position) and direction data (GPS direction),
The vehicle position (sensor position) and the traveling azimuth (sensor azimuth) are corrected by the self-contained navigation sensor. Actually, the distance D between the GPS position and the sensor position is calculated, and the distance D is compared with the preset distance threshold Dth. Then, only when D> Dth, the position and direction are corrected by the GPS data, and the vehicle position mark is put on the road by the map matching performed thereafter.

That is, the above distance threshold Dth is G
This figure shows the range allowable as the PS positioning error, and a circle whose radius is this is called an "error circle". Map matching by self-contained navigation becomes impossible, and GP
When the distance D between the S position and the sensor position becomes larger than the distance threshold value Dth, it is highly possible that the actual vehicle position is within the range of the GPS error circle. Make corrections.

The vehicle position can be easily corrected by replacing the GPS position with a new sensor position. Further, in correcting the traveling azimuth, an average value of differences between GPS azimuths at a plurality of points (n points) and a plurality of absolute traveling azimuths measured by the self-contained navigation at the same point is calculated, and this average is calculated. It is performed by correcting the offset angle up to now (the angle formed by the actual traveling direction of the vehicle and the reference direction) by the value.

[0012]

In the vehicle position measurement by GPS, when there is no obstacle such as a tunnel or a building around the vehicle, the absolute position is detected with a slight error of about 10 m. It is possible. Therefore, the error circle is usually set to be relatively small. However, if there is an obstacle such as a tall building around the vehicle, a large positioning error of 1 km or more sometimes occurs due to the influence of multipath of satellite radio waves. Further, when the receiving satellite is switched, a "jump" may occur at the position detected by GPS. Therefore, in such a case, accurate position detection cannot be performed.

However, conventionally, there is no means for judging the good or bad of the positioning state by GPS, and if the condition of D> Dth is satisfied, the position is corrected uniformly by GPS data. Therefore, if map matching by self-contained navigation becomes impossible at the time when the position measured by GPS includes many errors, the vehicle position is corrected using the position data by GPS that includes a large error. . Therefore, there is a problem that the vehicle position mark cannot be correctly corrected to the actual vehicle position on the map, and the traveling direction is different from the actual traveling direction.

Further, it is conceivable to set the GPS error circle larger than usual so that the GPS data including a large error will not correct the vehicle position and the like. However, in this case, even if the GPS data does not include a large error, D>
Since the Dth condition is not satisfied, the GPS position correction is often not performed. Therefore, there is a problem in that the position of the GPS positioning point cannot be corrected in many cases even though it is correct.

The present invention has been made to solve such a problem, and a first object of the present invention is to provide a means for judging the quality of a vehicle position measured by GPS. A second object of the present invention is to enable more appropriate position correction by GPS according to the above determination result when map matching by self-contained navigation becomes impossible. .

[0016]

In order to solve the above-mentioned problems, in the GPS positioning reliability determination method of the present invention, the mileage of a certain section (self-contained navigation mileage) obtained by self-contained navigation and GPS are obtained. And the reliability of the position data obtained by GPS according to the magnitude of the difference between the self-contained navigation distance and the distance between GPS positioning points, by comparing the distance of the section corresponding to the certain section (distance between GPS positioning points). Judge the degree. For example, it is determined that the smaller the difference between the self-contained navigation travel distance and the distance between the GPS positioning points, the higher the reliability, and the larger the difference, the lower the reliability. Alternatively, self-contained navigation mileage and G
It is determined that the smaller the ratio of the difference between the distance between the PS positioning points and the self-contained navigation travel distance, the higher the reliability, and the larger the ratio, the lower the reliability.

In the vehicle position correcting apparatus of the present invention to which this judgment method is applied, the distance threshold value is set according to the judged reliability. This distance threshold value is data serving as a comparison reference when determining whether or not to perform position correction based on GPS data when map matching by self-contained navigation becomes impossible. For example, the greater the difference between the self-contained navigation travel distance and the distance between GPS positioning points, the lower the reliability of GPS is determined, and the greater the distance threshold value is set. Conversely, the smaller the difference between the self-contained navigation travel distance and the distance between GPS positioning points, the higher the reliability of GPS is determined, and the distance threshold value is set to a small value.

According to the present invention thus constructed, when map matching by self-contained navigation becomes impossible,
It is possible to grasp whether the positioning state by GPS is good or bad, and increase the distance threshold when the positioning state is bad to make it less likely to be affected by an incorrect GPS positioning point. Further, when the positioning state is good, it is possible to easily correct the GPS positioning point by reducing the distance threshold value.

By the way, the self-contained navigation mileage used when determining the reliability of GPS may be a mileage in a specific distance section from the current position of the vehicle to the front by a predetermined distance, or may be a predetermined time from the current position of the vehicle. However, it may be the traveling distance in a specific time section up to this point. When the latter specific time section is used, when the vehicle is traveling at a relatively low speed, the GP is applied only to the section close to the current vehicle position.
It is possible to determine the reliability of S, make it less likely to be affected by the past old positioning state, and correct the current GP.
It is possible to obtain the S reliability.

According to another aspect of the present invention, the table information used when setting the distance threshold is set based on the ratio of the self-contained navigation mileage, the distance between GPS positioning points, and the distance difference. The first table information made and the second table information set based on the distance difference itself are provided, and the smaller one of the distance thresholds obtained from both table information is adopted. ing. With this configuration, it is possible to set an appropriate distance threshold value regardless of the vehicle speed.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION (First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings. Figure 1
It is a figure for explaining the outline of this embodiment, and (a) shows the situation when the GPS positioning state is good, and (b) shows the situation when the GPS positioning state is bad.

As shown in FIG. 1A, when the GPS positioning is good, the traveling locus by the self-contained navigation (indicated by ◯) and the locus of the positioning point by GPS (indicated by x) are almost the same. Match. Therefore, when focusing on a certain section (for example, from the own vehicle position CM to 200 m before), the travel distance measured using the self-contained navigation sensor (self-contained navigation travel distance L _trace ) and the GPS receiver in that section are obtained. The difference with the distance between the determined positioning points (distance between GPS positioning points L _gps ) is not so large.

In the case of self-contained navigation, the accessory (AC
It has mileage information after C) is turned on. Therefore, the self-contained navigation travel distance L _trace is obtained by subtracting the travel distance at the start point of the certain section from the travel distance at the end point of the certain section. To set a certain section from the current position of the vehicle to 200m before, set the current position to the end point of the section and
The point where the traveling distance is short by 200 m may be set as the starting point of the section.

The GPS inter-positioning point distance L _gps connects a plurality of positioning points from the positioning point corresponding to the start point of the certain section defined based on the positioning data of the self-contained navigation to the positioning point corresponding to the end point. It is obtained by adding all the length components of the vector. The time interval for positioning by self-contained navigation and the time interval for positioning by GPS are not necessarily the same, and the time interval for GPS positioning is often shorter. In this case, the number of positioning points is larger in GPS than in self-contained navigation. However, if the trajectory of the self-contained navigation and the trajectory of the positioning point of the GPS are substantially the same, the self-contained navigation distance L
_{The difference} between the _trace and the distance L _gps between the GPS positioning points does not become so large.

On the other hand, as shown in FIG.
When the positioning state of GPS is bad, the traveling locus by self-contained navigation and the locus of the positioning point by GPS deviate. Therefore, the difference between the self-contained navigation travel distance L _{trace in} a certain section and the GPS positioning point distance L _gps corresponding to the section becomes large. In the present embodiment, by utilizing such a property, the GP
The reliability of the position data obtained from the S receiver is determined.

That is, the self-contained navigation mileage L of a certain section
_trace and distance between GPS positioning points corresponding to the section L _gps
When the distance L _gps between GPS positioning points is abnormally larger than the self-contained navigation mileage L _trace (for example,
When the difference is 50% or more of the self-contained navigation travel distance L _{t race} ), it is determined that the reliability of GPS positioning is low. In this case, by setting the GPS error circle large, it becomes difficult for the vehicle position to be corrected to the wrong GPS positioning point.

On the contrary, when the difference between the GPS positioning distance L _gps and the self-contained navigation mileage L _trace is not large (for example,
When the difference is 50% or less of the self-contained navigation travel distance L _trace ), it is determined that the reliability of GPS positioning is high. In this case, the GPS error circle is set to be small so that the vehicle position can be easily corrected to the correct GPS positioning point.

Here, an example has been described in which the reliability of the positioning state by GPS is determined in two stages (whether the positioning state is good or bad), but the present invention is not limited to this. For example, it has table information as illustrated in FIG. 2, and determines the reliability of the positioning state by GPS in n steps (n ≧ 2) according to this table information, and determines the GPS error circle according to the reliability of n steps. The size of may be changed stepwise.

FIG. 3 is a diagram showing the overall configuration of a navigation system to which the vehicle position correcting device that realizes the above-described principle of this embodiment is applied. In FIG. 3, reference numeral 1 is a system controller, which controls the entire navigation system. The system controller 1 is composed of a microcomputer or the like, and performs a drawing process of a map and a vehicle position mark, an optimum route search process, a map matching process, a position correction process and the like.

Reference numeral 2 denotes a map storage medium for storing map information, which is composed of, for example, a DVD (digital video disk). The DVD-ROM 2 stores various map data necessary for map display and route search. In addition, here, as a recording medium for storing the map data, a DV is used.
Although the D-ROM 2 is used, another recording medium such as a CD-ROM or a hard disk may be used. 3 is DVD
The control unit controls reading of map information from the DVD-ROM 2.

Reference numeral 4 denotes an operation panel, which is constituted by a remote controller (remote control) or the like. This operation panel 4 allows the passenger to set various information (for example, offset angle) to the system controller 1 and various operations (for example, screen scroll, map search, enlargement / reduction, optimum route search, etc.) Various types of operating elements (buttons, joysticks, etc.) for performing the operation are provided, and an infrared signal according to the operating state of the operating elements is transmitted to the system controller 1.

A GPS receiver 5 receives radio waves sent from a plurality of GPS satellites by a GPS antenna 6 and performs a three-dimensional positioning process or a two-dimensional positioning process to calculate the absolute position and azimuth of the vehicle. (The vehicle direction is calculated based on the present vehicle position and the present vehicle position one sampling time ΔT before). Then, the information on the calculated absolute position and azimuth of the vehicle is output to the system controller 1 together with the positioning time.

Reference numeral 7 is a self-contained navigation sensor, which is provided with a relative azimuth sensor (angle sensor) 7a such as a vibration gyro that detects the rotation angle of the vehicle, and a distance sensor 7b that outputs one pulse for each predetermined traveling distance. ing. Autonomous navigation sensor 7
Detects the relative position and azimuth of the vehicle by the angle sensor 7a and the distance sensor 7b, and outputs the information to the system controller 1.

Reference numeral 8 denotes a display device, which displays map information around the vehicle along with a vehicle position mark, a departure point mark, a destination mark, and the like on the map based on the image data output from the system controller 1. The traveling locus and the guidance route are displayed in, and the intersection enlarged view is displayed when the position of the vehicle approaches the vicinity of the intersection. The display device 8 includes a CRT controller 21, a video R
AM (V-RAM) 22, read control unit 23 and CRT
24 are provided.

Next, the detailed configuration of the system controller 1 will be described. A map data buffer memory 11 is for temporarily storing the map data read from the DVD-ROM 2. Reference numeral 12 denotes a map reading control unit, which controls the reading of map data from the DVD-ROM 2. The map reading control unit 12 inputs the information on the current vehicle position from the vehicle position correcting unit 15, and stores the map data in a predetermined range including the current vehicle position on the DVD-ROM.
2 and stores it in the map data buffer memory 11.

Reference numeral 13 is a GPS data storage unit,
The absolute position and azimuth data of the vehicle output from the receiver 5 are sequentially stored. A vehicle position / azimuth calculation unit 14 calculates an absolute own vehicle position (estimated vehicle position) and a vehicle azimuth based on the relative position and azimuth data of the own vehicle output from the self-contained navigation sensor 7. To do. The vehicle position / azimuth calculation unit 14 also measures the traveling distance after the accessory (ACC) is turned on.

Reference numeral 15 denotes a vehicle position correction unit, which includes a map matching processing unit 15a, a vehicle position correction processing unit 15b, a distance threshold value setting unit 15c, and a running locus storage unit 15d. The traveling locus storage unit 15d stores the vehicle position and the vehicle azimuth at predetermined time intervals or predetermined traveling distances as a traveling locus based on the data output from the vehicle position / azimuth calculation unit 14. In addition, the distance information after the accessory (ACC) is turned on is also stored.

The map matching processing unit 15a and the map data read out to the map data buffer memory 11 and the travel locus data stored in the travel locus storage unit 15d (estimated by the vehicle position / azimuth calculation unit 14). The vehicle position and the vehicle direction data) are used to perform map matching processing by the projection method at predetermined time intervals or predetermined travel distances to correct the travel position of the host vehicle on the road of the map data.

The distance threshold setting unit 15c determines a distance threshold Dth (GPS error circle of the GPS error circle) for deciding whether or not to perform position correction by GPS data when map matching by self-contained navigation becomes impossible. Radius). Specifically, as described with reference to FIGS. 1 and 2, the self-contained navigation travel distance L _trace in a certain section (for example, from the vehicle position to 200 m before) and the GPS positioning point distance corresponding to the section. Compared with L _gps , the self-contained navigation mileage L
_The distance threshold Dth is set according to the magnitude of the difference between the _trace and the distance L _gps between the GPS positioning points.

At this time, the self-contained navigation mileage L _trace is
It is obtained based on the traveling locus data stored in the traveling locus storage unit 15d. In addition, the distance L between the GPS positioning points
_{The gps} is obtained based on the data of the GPS positioning point for each predetermined time stored in the GPS data storage unit 13.
That is, it is obtained by adding all the length components of the vector connecting a plurality of positioning points from the positioning point corresponding to the start point of the certain section to the positioning point corresponding to the end point.

The vehicle position correction processing section 15b uses the GPS when the map matching by self-contained navigation becomes impossible.
Vehicle position correction processing is performed based on the positioning data of. At this time, the vehicle position correction processing unit 15b calculates a distance D between the vehicle position (GPS position) obtained from the GPS receiver 5 and the vehicle position (sensor position) obtained from the self-contained navigation sensor 7, and the distance D And the distance threshold Dth set by the distance threshold setting unit 15c are compared. Then, only when the condition of D> Dth is satisfied, the position and direction of the vehicle are corrected by the positioning data of GPS.

Reference numeral 16 denotes a vehicle position mark generating section which inputs the current vehicle position after the map matching processing by the vehicle position correcting section 15 and generates a vehicle position mark to be displayed at the own vehicle position. Further, processing for inputting the traveling locus data from the vehicle position correcting unit 15 and generating the traveling locus is also performed. Reference numeral 17 denotes a map drawing control unit, which creates a map around the vehicle position based on the map data stored in the map data buffer memory 11, the vehicle position mark generated by the vehicle position mark generation unit 16 and the traveling locus. The map image data required to be displayed on the display device 8 together with the position mark and the traveling locus is generated.

The map image data generated by the map drawing control unit 17 is V-shaped by the CRT controller 21.
It is temporarily stored in the RAM 22. The read control unit 23
The reading of map image data from the V-RAM 22 is controlled. That is, the map image data generated by the map drawing control unit 17 is temporarily stored in the V-RAM 22, the map image data for one screen is read by the read control unit 23, and displayed on the display screen of the CRT 24. It

Next, the operation of the vehicle position correction process of the navigation system according to the present embodiment configured as described above will be described. FIG. 4 is a flowchart showing the overall flow of the vehicle position correction processing. In FIG. 4, the traveling locus storage unit 15d stores the current position and traveling azimuth data of the vehicle calculated from the output data of the self-contained navigation sensor 7 by the vehicle position / azimuth calculation unit 14 at predetermined time intervals or predetermined travel distances. The data are sequentially stored (step S1).

The map matching processing unit 15a has a running locus storage unit 15d for each predetermined time or for each predetermined traveling distance.
It is determined whether map matching is possible based on the self-contained navigation data stored in (step S2), and if possible, map matching processing is performed (step S3). On the other hand, when the vehicle position and the traveling direction calculated by the vehicle position / direction calculating section 14 deviate greatly from the actual traveling road and the map matching becomes impossible, the distance threshold setting section 15
c refers to the table information as shown in FIG. 2, for example, the self-contained navigation travel distance L _trace and the distance L between GPS positioning points L
A distance threshold Dth is set according to the magnitude of the difference from _gps (step S4).

Then, the vehicle position correction processing section 15b
The distance D between the vehicle position (GPS position) obtained from the PS receiver 5 and the vehicle position (sensor position) obtained from the self-contained navigation sensor 7 is calculated, and the distance D is the above-mentioned step S.
It is determined whether or not it is larger than the distance threshold Dth set in step 4 (step S5). If the condition of D> Dth is not satisfied, the processing is terminated without doing anything thereafter. On the other hand, when the condition of D> Dth is satisfied, the GPS receiver 5
The position and direction of the vehicle are corrected based on the positioning data of (step S6).

The data of the vehicle position corrected by the map matching process of step S3 or the vehicle position corrected by the vehicle position correction process of step S6 is input to the vehicle position mark generator 16. The vehicle position mark generation unit 16 generates a vehicle position mark so as to be displayed on the corrected current vehicle position. Map drawing control unit 17
Reads the vehicle position mark data from the vehicle position mark generation unit 16 and inputs it to the display device 8 to display the vehicle position mark at the corrected position on the map (step S).
7). After that, the process returns to step S1 and is repeated.

As described in detail above, according to the first embodiment, when the map matching by the self-contained navigation becomes impossible, it is possible to grasp the good or bad of the positioning state by GPS at that time. . Moreover, in the present embodiment, the GP using actual positioning point data by GPS is used.
Since the reliability of S is determined, the positioning state of GPS can be determined more accurately and in real time.
When the positioning state is poor, the distance threshold Dth is increased to prevent the inconvenience that the vehicle position is corrected to the wrong GPS positioning point. Further, when the positioning state is good, the distance threshold value Dth can be reduced to surely correct the GPS positioning point.

(Second Embodiment) Next, a second embodiment of the present invention will be described. FIG. 5 is a diagram for explaining the outline of the second embodiment, and shows a state including both a section where the GPS positioning state is poor and a section where the GPS positioning state is good.
For comparison with the first embodiment, the self-contained navigation mileage L _trace not used in the second embodiment is also shown in FIG.

The example shown in FIG. 5 shows a situation where the GPS positioning state was initially poor, but thereafter the GPS positioning state recovered. Further, it is assumed that the second half of the entire section shown in FIG. 5 is in a situation such as traffic jam or continuous waiting for a signal, and the traveling speed of the vehicle is relatively slow.

In the above-described first embodiment, the reliability of GPS is determined for a specific distance section (a section from the vehicle position CM to 200 m before, that is, a section represented by L _trace in FIG. 5). It was That is, no matter how long it took to run, the distance of the specific section to be determined was fixed at 200 m. Therefore, the current GPS
Although the reliability is high, it is possible that the correct current GPS reliability cannot be obtained due to the bad positioning state in the past.

Therefore, in the second embodiment, the GPS of the specific time section (for example, the section from the own vehicle position CM to 10 to 15 seconds before, that is, the section represented by L _trace 'in FIG. 5) is set as the target. Make sure to judge the reliability. That is, the self-contained navigation mileage L _trace 'in a certain specific time section
And the GPS positioning point-to-point distance L _gps ' corresponding to the section are compared, and the reliability of the GPS positioning is determined according to the magnitude of the difference between the self-contained navigation distance L _trace 'and the GPS positioning point distance L _gps '. Judge the degree.

In order to set a specific time section from the vehicle position CM to a predetermined time before, the own vehicle position CM is set to the end point of the section, and the point which has passed a predetermined time from there is set to the start point of the section. You can set it to. For a point passed by a predetermined time, for example, the traveling locus information calculated by the vehicle position / azimuth calculation unit 14 is stored in the traveling locus storage unit 15d together with the positioning time information output from the GPS receiver 5. You can easily find it.

In this way, when the GPS reliability is determined in the specific time section, the self-contained navigation travel distance L _trace 'of the specific section to be determined varies depending on the traveling speed of the vehicle. In particular, the self-contained navigation mileage L _{trac e} ′ becomes short under a situation such as traffic jam or continuous waiting for traffic lights. As a result, the GPS reliability can be determined only for the section close to the current position CM, and it is possible to obtain the correct current GPS reliability without being affected by the information that is too old.

Also in the second embodiment, the distance threshold Dth (radius of the GPS error circle) is determined according to the magnitude of the difference between the self-contained navigation traveling distance L _trace 'and the distance between GPS positioning points L _gps '.
To set. By setting the section for which the reliability is to be determined as the specific time section, when the vehicle is stopped for a certain period of time, the self-contained navigation travel distance L _trace 'is zero. In this case, if the GPS reliability is determined by converting the distance difference into the ratio with the self-contained navigation mileage L _trace 'as in the table shown in FIG. 2, the ratio of the distance difference when the vehicle is stopped becomes infinite, The GPS reliability is always determined to be poor.

Therefore, in the second embodiment, the table information as shown in FIG. 6 is provided, and not the ratio of the distance difference to the self-contained navigation travel distance L _trace ', but the self-contained navigation travel distance L.
The reliability of the positioning state by GPS is determined based on the distance difference itself between the _trace 'and the distance L _gps between the GPS positioning points,
The size of the GPS error circle is changed stepwise according to the reliability of n steps. The table shown in FIG. 6 is suitable for use when the vehicle speed is relatively low.

On the contrary, when the vehicle speed becomes faster,
Autonomous navigation mileage L corresponding to the section _trace’Is long
It In this case, although the ratio of the distance difference is small,
The body can be quite large. Therefore, the vehicle speed is high
GPS reliability according to the table information shown in FIG.
When the degree of reliability is judged, it is determined that the reliability of GPS is worse than it should be.
May be fixed. Therefore, as shown in FIG.
Using table information, the ratio of distance difference and the distance difference itself
GPS reliability is judged based on both of the above, and the better one is adopted.
It is preferable to do so. Thus, shown in FIG.
By using the table information, what kind of vehicle speed
However, the correct GPS reliability can be determined.

FIG. 8 is a flow chart showing the operation when setting the distance threshold Dth (radius of GPS error circle) using the table information shown in FIG. In FIG. 8, first, the self-contained navigation mileage L _trace 'and the distance L between GPS positioning points L
The ratio of the distance difference from _gps ' is calculated (step S1
1) Find the distance difference itself (step S12).

Then, based on the ratio obtained in step S11, the table information of FIG. 7 is referred to, and G corresponding to the ratio is referred to.
The radius of the PS error circle is calculated (step S13). Also,
Based on the distance difference obtained in step S12, the radius of the GPS error circle corresponding to the distance difference is obtained by referring to the table information of FIG. 7 (step S14). Finally, the above step S
Both GPS error circle radii obtained in step 13 and step S14 are compared, and the smaller one is set as the final GPS error circle radius (step S15).

As described in detail above, according to the second embodiment, when the map matching by the self-contained navigation becomes impossible, it is possible to grasp the quality of the positioning state by GPS at that time. . In particular, when the traveling speed is slow due to traffic congestion or waiting for traffic lights, more accurate current GPS reliability can be obtained without being affected by old information. Then, when the positioning state is bad, the distance threshold Dth is increased to increase the wrong GPS.
It is possible to prevent the inconvenience that the vehicle position is corrected to the positioning point. Further, when the positioning state is good, the distance threshold value Dth can be reduced to surely correct the GPS positioning point.

In the second embodiment, the self-contained navigation travel distance L _trace 'is first set as a specific time section from the vehicle position CM to the front of the predetermined time, and the GPS positioning point distance L of the section corresponding thereto is set. _{Although gps} ' is obtained and the two are compared, conversely, first, the distance between GPS positioning points L _gps ' is set, and the self-contained navigation mileage L _trace 'of the section corresponding to that is set.
It is also possible to obtain and compare the two.

In addition, each of the above-described embodiments is merely an example of the embodiment for carrying out the present invention, and the technical scope of the present invention should not be limitedly interpreted by these. Is. That is, the present invention does not depart from the spirit or the main features thereof,
It can be implemented in various ways.

[0063]

As described above, according to the present invention,
Depending on the magnitude of the difference between the traveling distance of a certain section obtained by self-contained navigation (self-contained navigation traveling distance) and the distance of a section corresponding to the certain section obtained by GPS (distance between GPS positioning points), Since the reliability of the obtained position data is determined, it is possible to grasp the quality of the positioning state by GPS.

Further, the distance threshold serving as a comparison reference for deciding whether or not to perform position correction by GPS when map matching by self-contained navigation becomes impossible is changed according to the above-mentioned judgment result. Therefore, if the positioning is bad, increase the distance threshold and
It is possible to reduce the influence of the PS positioning point, and when the positioning state is good, it is possible to reduce the distance threshold value and to easily correct the GPS positioning point.
This makes it possible to more appropriately correct the position when map matching cannot be performed, depending on the positioning state of GPS.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an outline of a first embodiment.

FIG. 2 shows a distance threshold (GPS
It is a figure which shows the example of the table information used when setting an error circle.

FIG. 3 is a diagram showing an overall configuration of a navigation system to which the vehicle position correcting device of the present embodiment is applied.

FIG. 4 is a flowchart showing the overall flow of vehicle position correction processing according to the present embodiment.

FIG. 5 is a diagram for explaining the outline of the second embodiment.

FIG. 6 is a distance threshold (GPS
It is a figure which shows the example of the table information used when setting an error circle.

FIG. 7 shows a distance threshold (GPS
It is a figure which shows the other example of the table information used when setting an error circle.

8 is a flowchart showing an operation when setting a radius of a GPS error circle using the table information shown in FIG.

FIG. 9 is a diagram for explaining map matching by a projection method.

[Explanation of symbols]

1 System controller 2 DVD (map storage medium) 3 DVD control unit 4 control panel 5 GPS receiver 6 GPS antenna 7 Self-contained navigation sensor 7a Angle sensor 7b Distance sensor 8 display devices 11 Map data buffer memory 12 Map read control unit 13 GPS data storage 14 Vehicle position / direction calculator 15 Vehicle position correction unit 15a Map matching processing unit 15b Vehicle position correction processing unit 15c Distance threshold setting unit 15d Running locus storage unit 16 Vehicle position mark generator 17 Map drawing controller 21 CRT controller 22 V-RAM 23 Read Control Unit 24 CRT

Claims (12)

[Claims] 1. A map is drawn on a display screen based on map data, a vehicle position is measured by self-contained navigation, a vehicle position mark is displayed on the map, and the vehicle position mark is appropriately displayed on a map by a map matching process. A vehicle position correcting device for a navigation system that corrects the vehicle position data obtained by the above-mentioned self-contained navigation by using the position data obtained by GPS when the map is corrected as shown above and the map matching becomes impossible. When the map matching becomes impossible, the traveling distance of a certain section obtained by the self-contained navigation (self-contained navigation traveling distance) and the distance of the section corresponding to the certain section obtained by the GPS (GPS positioning point). Distance),
Threshold setting means for setting a distance threshold according to the magnitude of the difference between the self-contained navigation mileage and the distance between the GPS positioning points, the vehicle position obtained by the GPS, and the vehicle obtained by the self-contained navigation. If the distance to the position is calculated and the distance is equal to or less than the distance threshold, the vehicle position is not corrected by the GPS position data. A vehicle position correcting device, comprising: a position correcting means for correcting a position. 2. The threshold value setting means is such that the smaller the difference between the self-contained navigation travel distance and the distance between the GPS positioning points, the smaller the distance threshold, and the larger the difference, the greater the distance threshold. The vehicle position correction device according to claim 1, wherein the distance threshold value is set so as to be large. 3. The vehicle position correcting device according to claim 1, wherein the self-contained navigation mileage is a mileage in a specific distance section from a current vehicle position to a front side by a predetermined distance. 4. The threshold value setting means is such that the smaller the ratio of the difference between the self-contained navigation travel distance and the distance between the GPS positioning points to the self-contained navigation travel distance, the smaller the distance threshold value, and the ratio is The vehicle position correcting device according to claim 3, wherein the distance threshold value is set based on table information that is set such that the greater the distance value, the greater the distance threshold value. 5. The vehicle position correcting device according to claim 1, wherein the self-contained navigation mileage is a mileage in a specific time section from a current vehicle position to a front side by a predetermined time. 6. The threshold value setting means is such that the smaller the difference between the self-contained navigation distance and the distance between the GPS positioning points, the smaller the distance threshold, and the larger the difference, the greater the distance threshold. The vehicle position correction device according to claim 5, wherein the distance threshold value is set based on table information set to be large. 7. The threshold value setting means, the smaller the ratio of the difference between the self-contained navigation travel distance and the distance between the GPS positioning points to the self-contained navigation travel distance, the smaller the distance threshold value, and the ratio is The larger the first table information set such that the greater the distance threshold is, the smaller the difference between the self-contained navigation distance and the distance between the GPS positioning points, the smaller the distance threshold, and the difference. The second table information is set such that the greater the distance, the greater the distance threshold, and the second table information is obtained based on the first table information. 6. The vehicle position correcting device according to claim 5, wherein the distance threshold value is obtained based on the above, and whichever is smaller is set. 8. The self-sustaining device is compared by comparing the traveling distance of a certain section obtained by self-contained navigation (self-contained navigation traveling distance) with the distance of a section corresponding to the certain section obtained by GPS (distance between GPS positioning points). A GPS positioning reliability determination method, characterized in that the reliability of position data obtained by the GPS is determined according to the magnitude of the difference between the navigation travel distance and the distance between the GPS positioning points. 9. The reliability is determined to be higher as the difference between the self-contained navigation travel distance and the distance between the GPS positioning points is smaller, and the reliability is lower as the difference is larger. The GPS positioning reliability determination method described in 1. 10. It is determined that the smaller the ratio of the difference between the self-contained navigation mileage and the distance between the GPS positioning points to the self-contained navigation mileage, the higher the reliability, and the larger the ratio, the lower the reliability. 9. The method according to claim 8, wherein
The GPS positioning reliability determination method described in 1. 11. The GPS according to claim 8, wherein the self-contained navigation mileage is a mileage in a specific distance section from a current vehicle position to a front side by a predetermined distance.
Positioning reliability determination method. 12. The GPS according to claim 8, wherein the self-contained navigation mileage is a mileage in a specific time section from a current vehicle position to a front side by a predetermined time.
Positioning reliability determination method.