JP3084087B2 - Vehicle position recognition device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects the current position of a vehicle using radio signals received from each of three or more of a plurality of satellites in orbit around the earth mounted on the vehicle. The present invention relates to an own-vehicle position recognizing device.

[0002]

2. Description of the Related Art JP-A-61-209316 discloses that
2. Description of the Related Art A vehicle route guidance apparatus has been disclosed which integrates traveling distances starting from each intersection to accurately detect a point in time at which the vehicle has passed each intersection. This navigation device uses navigation that detects a relative position from a reference point, that is, navigation called dead reckoning navigation or self-contained navigation. However, when only dead reckoning navigation is used for recognizing the position of the own vehicle, occurrence of a large cumulative error is inevitable. Therefore, navigation that detects the absolute position of the vehicle using radio signals from a plurality of satellites launched in orbit around the earth, that is, satellite navigation (Global Positionio).
ning System: Abbreviated as GPS. ) Has already been used to correct the position estimated by dead reckoning navigation.

[0003] In the GPS, when the system is completed, six circular orbits (orbit radius about 26600 km) with different right ascensions at the ascending intersection point
A total of 24 satellites, four on each, are placed so that there are always more than three satellites in view anywhere on the globe. The orbit of each satellite is about 11 hours and 58 minutes.

[0004] Each satellite transmits a radio signal including the latest orbital information and transmission time information by an extremely accurate atomic clock toward the ground. The GPS receiver mounted on the vehicle has 4
While receiving the radio signals of each of the satellites and calculating the three-dimensional position of each satellite at that moment from the orbit information, each radio signal is calculated based on the difference between the transmission time information and the reception time by the clock inside the receiver. The required arrival time of the signal, that is, the pseudo distance between each satellite and the position of the own vehicle (it is called a pseudo distance because it is not an accurate distance value at this stage). Then, four spherical surfaces are set with each satellite as a center and each pseudo distance from the center as a radius. However, since the internal clock of the GPS receiver does not completely match the atomic clock of the satellite, the four spherical surfaces do not intersect at one point. Therefore, the pseudorange is corrected by correcting the internal clock so that the four spheres intersect at one point, and the time of the internal clock is adjusted, and at the same time, the intersection of the four spheres, that is, the absolute position of the own vehicle is calculated. is there. However, since the vehicle is on the earth, positioning using radio signals of only three satellites is possible.

[0005] The positioning result by the GPS described above contains some error, and the positioning error differs depending on the arrangement of the satellite used for position detection on the sky. For example, when the satellites are unevenly distributed in a specific direction on the sky, the positioning accuracy deteriorates. So in GPS, DO
A quantity called P (Dilution of Precision) is defined, and is used as a measure of how much the satellite arrangement affects the positioning accuracy. The combination of satellites that minimizes the DOP value is adopted.

FIG. 4 is a time chart showing actual measurement data of a change in the DOP value over time. Since the arrangement of satellites changes every moment, the DOP value also changes accordingly. When a vehicle enters a mountain or a building, a radio signal from a satellite at a low altitude which should be receivable is blocked, so that the available range of the satellite is restricted and the DOP value changes. A situation where positioning cannot be performed may occur.

DOP is a quantity that can be determined by a GPS receiver from the geometrical arrangement of available satellites. However, SVACC (Spac) is also included in the radio signal transmitted by each satellite.
Information that is a measure of positioning accuracy called eVehicle Accuracy) is included. When the value of SVACC is N (0 <N <15), the positioning error e (unit:
m) is determined by the following equation in combination with the DOP value.

E = DOP ^× X However, when 0 <N <6, X = 2 ^{(1 + N / 2)} , and when 6 ≦ N <15, X = 2 ^(N−2) .

For example, when the DOP value is 4 and the SVACC value is 6, e = 4 × 2 ⁽⁶⁻²⁾ = 4 × 16 = 64, which indicates that there is a positioning error of 64 m. SV
When the ACC value is 4 to 5, when the DOP value is 4, about 40
m, DOP value is 10, about 100 m, DOP value is 2
When it is 0, a positioning error of about 200 m appears.

Conventionally, GPS is used only when the DOP value is 4 or less and the SVACC value is 8 or less due to the relationship with the so-called map matching technique. That is, three or more satellites capable of detecting the position with an accuracy higher than the positioning accuracy are selected, and the current position of the vehicle is calculated using the radio signal received from each of the selected satellites.

[0011]

As described above, in the conventional vehicle position recognition device, the DOP value is 4 or less and the SVACC
Since the GPS is used only when the condition of the value of 8 or less is satisfied, only dead reckoning navigation is used in a time zone where the GPS is not used. In dead reckoning, the relative position of the vehicle is estimated based on a direction sensor such as a geomagnetic sensor or a distance sensor such as a wheel speed sensor.

FIG. 5 shows a CRT when only the dead reckoning navigation is used because the condition that the DOP value is 4 or less and the SVACC value is 8 or less is not satisfied in the conventional vehicle position recognition apparatus.
It is a top view showing the example of the run locus displayed on the map screen of the monitor. This self-vehicle position recognition device displays the current position and the direction of the self-vehicle at every moment on a map screen including a road display 51 as an arrow-shaped current position mark 52, and sequentially displays a running locus as a locus mark 53. Things. However, the position estimated by dead reckoning usually has an error of 5 to 10%. When passing through a tunnel with large geomagnetic disturbance or traveling on a tram line, the vehicle body may be magnetized and the azimuth sensor may be deviated, and the position detection error by dead reckoning may exceed 10%. 10%
When the vehicle travels a distance of 10 km, the accumulated error becomes large as shown in FIG.
The current location mark 52 is displayed as if it is 1 km away from 4.

On the other hand, reference numeral 55 in the figure denotes a circle having a constant DOP value, ie, a DOP area, representing a positioning error assuming execution of absolute position detection by GPS.
The case where the positioning accuracy of S is lowered and the DOP upper limit is set to 20 is shown. The radius of this DOP area 55 is 200 m
And the current location mark 5 obtained only by dead reckoning navigation.
2 is out of the DOP area 55. In other words, although the position was more accurately detected than the dead reckoning by using the GPS with the DOP 20, even in such a case, the GPS is conventionally used unless the condition that the DOP value is 4 or less and the SVACC value is 8 or less is satisfied. I didn't use it.

An object of the present invention is to effectively utilize GPS and to more accurately detect the current position of a vehicle.

[0015]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention positively utilizes a positioning accuracy range of a GPS which has not been conventionally used.

More specifically, the invention of claim 1 is
A self-vehicle position recognition device mounted on a vehicle for detecting a current position of the vehicle using radio signals received from each of three or more satellites among a plurality of satellites in orbit around the earth. Accuracy specifying means for specifying positioning accuracy at the time of detection of the current position of the vehicle, and a position having an accuracy equal to or higher than the specified positioning accuracy among the plurality of satellites in orbit around the earth Satellite selection means for selecting three or more satellites capable of detection, position calculation means for calculating the current position of the vehicle using radio signals received from each of the selected satellites, and designation Less than the first positioning accuracy
There is a combination of satellites that enables high accuracy position detection
The current position of the vehicle based on the combination of those satellites
Position detection and position detection with an accuracy higher than the first positioning accuracy
Accuracy when no satellite combination exists
The positioning accuracy of the positioning means is changed from the first positioning accuracy to the second positioning accuracy.
Accuracy higher than the second positioning accuracy
Vehicle based on a combination of satellites that allows
Accuracy correction means for calculating the current position, at least
Also enables satellites to detect positions with an accuracy higher than the second positioning accuracy
Said satellite so that it can be adopted when the combination of
The current position of the vehicle without using radio signals from
Dead reckoning means for determining the position based on the second positioning accuracy
Centering on the current position of the vehicle calculated by the calculation means
Dead reckoning with the area within the circle as the error range of the second positioning accuracy
The current position of the vehicle estimated by the means is
Inferred by dead reckoning when within the error range
Selects the current position of the vehicle and is estimated by dead reckoning
If the current position of the damaged vehicle is out of the error range of the second positioning accuracy
Is calculated by the position calculating means based on the second positioning accuracy.
Recognition result selecting means for selecting the current position of the selected vehicle
Are adopted.

Further, according to the invention of claim 2 , the finger is set within a predetermined time.
Enables position detection with an accuracy higher than the specified first positioning accuracy
Make sure that there are no satellite combinations
Degree correction means specifies the positioning accuracy of the accuracy specifying means as the first positioning
Decreased from the accuracy to the second positioning accuracy
It is. Furthermore, the invention of claim 3 is characterized in that the second positioning accuracy is incorrect.
The radius of the circle representing the difference range is determined according to the second positioning accuracy.
Is a fixed value.

[0018]

According to the invention of claim 1, usually by selecting three or more satellites as a first positioning accuracy or a predetermined recognizing the current position of the vehicle. In addition, the satellite with the first positioning accuracy
If the star combination does not exist,
Set a low second positioning accuracy and set the second positioning accuracy
Satellites on condition that they are based on a combination of satellites above
After calculating the current position of the vehicle by navigation,
Second positioning accuracy centering on the current position (calculated position)
Set a circle that represents the error range of
Current position (estimated position) of the vehicle that is located within the error range
The estimated position, the estimated position
If it is outside the range, the position calculated by the above satellite navigation
Select each. Therefore, it is not used
Effective use of the positioning accuracy range of satellite navigation
The current position can be detected more accurately. However,
When there is no combination of satellites with the second positioning accuracy or better
Is a dead reckoning navigation system without forcing the use of radio signals from satellites.
Adopt the positioning result by step.

According to the second aspect of the present invention, the predetermined time
That can detect a position with an accuracy higher than the first positioning accuracy
After confirming that there is no star combination,
Degree designation reduced from 1st positioning accuracy to 2nd positioning accuracy
You. As a result, it may be affected by temporary disturbance of the radio signal, etc.
It becomes difficult to shake. Further, according to the third aspect of the present invention, the second
The radius of the circle representing the error range of the positioning accuracy is determined by the second positioning accuracy.
Is a fixed value according to. As a result, the estimated position is
(2) It is easy to determine whether the position is within the error range of the positioning accuracy.
Becomes easier.

[0020]

FIG. 1 is a block diagram showing the configuration of a vehicle position recognizing device according to an embodiment of the present invention. As shown in FIG. 1, the host vehicle position recognition device includes a GPS receiver 10 and a host vehicle position determination unit 20.

The GPS receiver 10 has a DOP designation unit 11,
A satellite combination determination unit 12, a satellite combination instruction unit 13, a satellite signal reception unit 14, and an absolute position calculation unit 15 are provided. DOP
The specifying unit 11 constitutes accuracy specifying means for specifying the positioning accuracy when detecting the current position of the vehicle, and usually sets the DOP upper limit to, for example, 4. The satellite combination determining unit 12 and the satellite combination instructing unit 13 determine three or more satellites capable of detecting a position with an accuracy that satisfies the DOP condition specified by the DOP specifying unit 11 among a plurality of satellites in orbit around the earth. It constitutes a satellite selection means for selection. Satellite signal receiving unit 1
The absolute position calculating unit 4 and the absolute position calculating unit 15 constitute position calculating means for calculating the current absolute position of the vehicle using radio signals received from each of the selected satellites.

The vehicle position determination unit 20 includes a current position estimation unit 2
1, a comparison unit 22, a GPS use determination unit 23, and a DOP instruction unit 24. An orientation sensor (a geomagnetic sensor, a wheel rotation sensor attached to each of the left and right wheels, a switch for distinguishing between forward and backward) 31 and a distance sensor (wheel speed sensor) 32 are connected to the current position estimation unit 21. Dead reckoning means for relatively estimating the current position of the vehicle without using a radio signal from a satellite is configured. The GPS use determining unit 23 and the DOP instructing unit 24 have a DOP value of 4 or less.
Satellite combinations, if any,
Calculation of the current absolute position of the vehicle based on the
When there is no combination of satellites having an OP value of 4 or less ,
The DOP upper limit setting of the DOP specifying unit 11 is changed from 4 to, for example, 2
By changing to 0, satellites with a DOP value of 20 or less
An accuracy correcting means for calculating the current absolute position of the vehicle based on the combination of the above. The comparison unit 22 outputs the DOP
When the value is changed, it is obtained by the absolute position calculator 15
The absolute position calculation result by GPS and the current position estimation unit 21
Compare the obtained relative position estimation results, and
It constitutes a recognition result selection means for selecting one of Chi. The comparison unit 22 is connected to a display unit 33 including a CRT monitor. The display unit 33 displays the current position of the vehicle on a map screen from time to time based on the output of the comparison unit 22.

FIG. 2 is a flowchart showing the operation of the vehicle position recognizing device according to the embodiment described above. The operation of the vehicle position recognition device of FIG. 1 will be sequentially described with reference to FIG.

As shown in FIG. 2, in step S1, it is checked whether or not the output of the absolute position calculator 15 of the GPS receiver 10 having the normal value 4 as the upper limit of the DOP is used. GPS
If it is used, the operation is continued. If GPS is not used, the DOP upper limit is set to 4 in step S2.
To check if it is a time zone in which GPS can be used. D
If it is not the time zone in which the GPS can be used in OP4, the flow advances to step S4 to change the designation of the DOP upper limit to 20. However, even in the time zone when the GPS can be used in DOP4, a radio signal from a satellite at a low altitude which should be able to receive the vehicle when entering the mountain or building may be interrupted. G within DOP4 within hours
Step S after confirming that PS is not used
At 4, the DOP upper limit is changed to 20.

When switching to the DOP 20 as described above, first, in step S5, it is checked whether or not the current position display based on the output of the current position estimating unit 21 is within the DOP area. D
The OP area is a circle having a constant DOP value representing a positioning error by GPS as described above, and a circle having a radius of 200 m corresponding to DOP 20 is considered. Current location estimation unit 2
If the current position display based on the output of No. 1 is in the DOP area, the process skips step S6 and proceeds to step S7. On the other hand, if the current position display based on the output of the current position estimation unit 21 goes out of the DOP area as in the case of FIG. 5, the current position display is calculated in step S6 by the absolute position calculation of the GPS receiver 10. After changing the output of the unit 15, that is, the GPS position, the process proceeds to step S7. In step S7, it is checked again whether or not it is a time zone in which the GPS can be used in DOP4, and if it has not returned to the time zone, the operation of DOP20 in steps S5 and S6 is continued. If the time has returned to the time zone in which GPS can be used in DOP4, the DOP designation is returned to 4 in step S8, and the process returns to step S1.

According to the vehicle position recognizing device according to the present embodiment described above, three or more satellites whose DOP value is usually 4 or less are selected to recognize the current position of the vehicle, and the DOP value is determined. DOP when there are no more than four satellite combinations
The current position of the vehicle is calculated based on the combination of satellites whose upper limit has been changed to 20. Moreover, when there is no combination of satellites having a DOP value of 4 or less, the DOP upper limit value is changed to 20, and if the current position display based on the output of the current position estimating unit 21 is in the DOP area, When the current position display is selected and the current position display goes out of the DOP area, the output of the absolute position calculation unit 15 based on the GPS is adopted as the accurate current position display. GPS positioning accuracy range can be effectively used, and the current position of the vehicle can be detected more accurately. However, a combination of satellites with a DOP value of 20 or less
When there is no GPS, the absolute position calculator based on GPS
Since 15 outputs cannot be obtained, use GPS as in the past.
Without using the current location display based on the output of the current location estimation unit 21
adopt.

In the above description, the case where the DOP upper limit is switched between two levels of 4 and 20 has been described.
It may be set to another value. GP constituting accuracy correction means
The S use determining unit 23 and the DOP instructing unit 24 may be built in the GPS receiver 10.

The upper limit of SVACC may be switched together with the upper limit of DOP or independently. When switching the SVACC upper limit, SVACC is used for GPS.
Since the available time zone is not determined by the satellite constellation, it is checked whether or not GPS using a predetermined normal value as the SVACC upper limit value is used.
After confirming that the system is not used, the SVACC upper limit value is increased. After the GPS positioning accuracy is reduced by changing the SVACC upper limit value in this way, the DOP
The process proceeds as in the case of changing the upper limit . However, the SVA after the change until the power of the own vehicle position recognition device is turned off.
Maintain the CC upper limit.

Information on what route the driver has traveled so far is very effective in recognizing the position of the vehicle. FIG. 3 is a plan view showing an example of a travel locus display on a map screen on the display unit 33 of the host vehicle position recognition device.

FIG. 5A shows a case where the display of the own vehicle position by dead reckoning navigation is corrected based on the detection result of the own vehicle absolute position by the GPS every fixed time. In this own-vehicle position recognition device, the current position and the direction of the own vehicle are displayed on a map screen including a road display 41 every moment as an arrow-shaped current position mark 42, and the running locus is sequentially displayed as a locus mark 43. Is done. Coordinates (X, Y) on the map screen of FIG.
Are coordinates corrected by use of GPS, and are accurately located on the road display 41. However, these coordinates (X,
Y) The result of the position detection error by dead reckoning navigation based on
Actually, until the vehicle reaches spite coordinates running on a road (X _1, Y ₁₎ deviates locus mark 43 from the road display 41, the coordinates (X _1, Y ₁₎ is Next G
The trajectory mark 43 returns to the road display 41 only after being corrected to the coordinates (X ₂ , Y ₂ ) on the road display 41 at the time of using the PS. From such a progress, the display of the traveling locus becomes zigzag even though the vehicle actually travels straight on the road, and conversely the driver's own vehicle position recognition is confused.

On the other hand, FIG. 3B shows a case where the display of the traveling locus in a certain range is corrected simultaneously with the correction of the display of the vehicle position. GPS (X ₁ , Y ₁ ) based on dead reckoning
When correcting to the exact coordinates (X ₂ , Y ₂ ) by using
By rotating a traveling trajectory based on dead reckoning navigation from the coordinates (X, Y) to the coordinates (X ₁ , Y ₁ ) around the coordinates (X, Y) related to the previous use of GPS,
The display position of the locus mark 44 is moved on the road display 41. As a result, the arrangement of the trajectory marks 44 is arranged on a straight line corresponding to the actual traveling trajectory.

[0032]

As described above, according to the first aspect of the present invention, it is usually possible to obtain the first positioning accuracy or more.
Recognize the current position of the vehicle by selecting three or more satellites,
If there is no combination of satellites with more than one positioning accuracy,
Set the second positioning accuracy lower than the first positioning accuracy
Based on a combination of satellites that exceed the second positioning accuracy
Under current conditions, the current position of the vehicle is calculated by satellite navigation.
In addition, the calculated current position (calculated position) is
Set the circle representing the error range of the second positioning accuracy as guessed
The current position (estimated position) of the vehicle estimated by the navigation means is
When it is within the error range, the estimated position is
When the estimated position is outside the error range, the satellite
Adopted a configuration to select each position calculated by navigation
So, the GPS positioning accuracy range that was not used before
Active use makes the current position of the vehicle more accurate
It can be detected reliably.

According to the second aspect of the present invention, the predetermined time
That can detect a position with an accuracy higher than the first positioning accuracy
After confirming that there is no star combination,
Degree designation is reduced from the first positioning accuracy to the second positioning accuracy
Affected by temporary disturbance of the radio signal, etc.
It becomes difficult to shake. Further, according to the third aspect of the present invention, the second
The radius of the circle representing the error range of the positioning accuracy is determined by the second positioning accuracy.
, The above-mentioned estimated position becomes the second value.
Easy to judge whether it is within the error range of positioning accuracy
become.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a host vehicle position recognition device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the host vehicle position recognition device of FIG. 1;

FIG. 3 is a plan view showing an example of display of a traveling locus on a map screen on a display unit in FIG. 1, wherein (a) shows dead reckoning navigation based on a detection result of an absolute position of a vehicle by a GPS at regular time intervals. (B) shows a case where the display of the own vehicle position is corrected according to the above, and (b) shows a case where the display of the traveling locus in a certain range is also corrected at the same time.

FIG. 4 is a time chart showing actual measurement data of a time change of a DOP value in GPS.

FIG. 5 is a plan view showing an example of a travel locus display on a map screen for explaining the accumulated error of the own vehicle position display when only dead reckoning navigation is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... GPS receiver 11 ... DOP designation | designated part (accuracy designation | designated means) 12 ... Satellite combination determination part (satellite selection means) 13 ... Satellite combination designation | designated part (satellite selection means) 14 ... Satellite signal reception part (position calculation means) 15 ... Absolute position calculation unit (position calculation unit) 20: own vehicle position determination unit 21: current position estimation unit (dead-reckoning navigation unit) 22 ... comparison unit (recognition result selection unit) 23 ... GPS use determination unit (accuracy correction unit) 24 ... DOP Indication section (accuracy correction means) 31 ... azimuth sensor (dead reckoning means) 32 ... distance sensor (dead reckoning means) 33 ... display section 41, 51 ... road display 42, 52 ... present position mark 43, 44, 53 ... locus mark 54 … True car position 55… DOP area

Claims (3)

(57) [Claims] A self-vehicle position recognition device for detecting a current position of a vehicle using a radio signal received from each of three or more satellites among a plurality of satellites in orbit around the earth mounted on the vehicle. An apparatus, comprising: an accuracy specifying means for specifying positioning accuracy when detecting a current position of a vehicle; and detecting a position having an accuracy equal to or higher than the specified positioning accuracy among a plurality of satellites on the orbit of the earth. a satellite selecting means for selecting three or more satellites which allow, and position calculating means for calculating a current position of the vehicle by using a radio signal received from each of the selected satellite, designated Position detection with accuracy higher than the first positioning accuracy
If there is a combination of satellites that
The current position of the vehicle is calculated based on the
A set of satellites that enables position detection with more than one positioning accuracy
When there is no alignment, the positioning
Degree designation is reduced from the first positioning accuracy to the second positioning accuracy
The accuracy of the second positioning accuracy or higher.
Vehicle current based on satellite combinations that enable location detection
Accuracy correcting means for calculating the position, and position detection with an accuracy at least equal to or higher than the second positioning accuracy is possible.
Can be adopted when there is no satellite combination to enable
As described above, the current position of the vehicle is estimated without using the radio signal.
Dead reckoning means for calculating the position and the position calculating means based on the second positioning accuracy.
The range within the circle centered on the current position of the issued vehicle is
As the error range of the second positioning accuracy, the dead reckoning means
The estimated current position of the vehicle is the error of the second positioning accuracy.
If it is within the range, it was inferred by the dead reckoning means
Select the current position of the vehicle and guess by the dead reckoning means
Position of the detected vehicle is outside the error range of the second positioning accuracy
, The position calculation based on the second positioning accuracy
Means for selecting the current position of the vehicle calculated by the means
An own-vehicle position recognizing device comprising: a recognition result selecting unit . 2. The self-vehicle position recognition device according to claim 1, wherein the accuracy correcting means is configured to perform the first positioning accuracy or less within a predetermined time.
There is a combination of satellites that can detect a position with higher accuracy.
After confirming that there is no
The degree designation is subtracted from the first positioning accuracy to the second positioning accuracy.
An own-vehicle position recognition device characterized by being lowered. 3. The self-vehicle position recognition device according to claim 1.
Te, the radius of a circle that represents the error range of the second positioning accuracy, the first
(2) own vehicle characterized by a fixed value according to positioning accuracy
Position recognition device.