JPH07248230A - Navigation apparatus - Google Patents

Abstract

PURPOSE:To determine a present position of a reliability of a fixed level or a higher level at all times with characteristics of both navigations supplemented, by determining a temporary present position obtained by a radio navigation as a final present position if a reliability of a temporary present position obtained by a self-contained navigation is not higher than a fixed value. CONSTITUTION:According to a self-contained navigation, a moving direction and a moving distance obtained by a direction/distance calculation process are read out from a memory 216 and a moving amount is obtained in a direction of latitudes and a direction of altitudes separately. A temporary present position is obtained by adding the obtained moving amount to a present position determined before. On the other hand, according to a radio navigation, a position obtained through a serial interface 218 from a GPS receiver 205 is read by a microprocessor 215, whereby the position obtained by the GPS receiver 205 is set as the temporary present position. If the temporary present position obtained according to the self-contained navigation is not higher than a fixed value, a controller 210 determines the temporary present position obtained by the radio navigation as a final present position. If the reliability is larger than the fixed value, the temporary present position by the self-contained navigation is determined as the final present position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for measuring the position of a navigation device used in a moving body such as an automobile.

[0002]

2. Description of the Related Art As a conventional navigation device technology,
Self-contained navigation and radio navigation technologies are known.

In self-contained navigation used in a navigation system for automobiles, usually, the estimated current value obtained from the measured values of a direction sensor such as a geomagnetic sensor or a gyro and a vehicle speed sensor is compared with the road map information to determine the current position. decide. In radio navigation, the current position is determined from radio waves received from GPS satellites.

However, in the self-contained navigation, the current position may not be calculated correctly when the error of the sensor is accumulated and becomes large, or when the road map information is inaccurate. In addition, radio navigation cannot accurately calculate the current position in a tunnel where radio waves cannot be received or in a high-rise building street where radio waves are reflected.

Therefore, in order to solve such a problem, it has been conventionally practiced to use a combination of self-contained navigation and radio navigation.

[0006] For example, in the technique disclosed in Japanese Patent Publication No. 5-7643, the possible position range of the current position is determined in consideration of the error range of each sensor used for self-contained navigation, and the current position is determined by radio navigation. When the current position is included, the current position obtained by this radio navigation is set as the final current position, and when the current position determined by the radio navigation is not included in the possible existing range, this radio navigation is used. The position within the possible existence range that is closest to the calculated current position is set as the final current position.

[0007]

With the technique described in Japanese Patent Publication No. 5-7643, when the self-contained navigation determines a wrong position as the current position, the current position thereafter is the self-contained navigation. Since it is limited to the range determined by the current position obtained in step 1 and the error range of each sensor, it takes time to return to the correct current position, and the reliability of the current position during this period becomes significantly low.

By the way, the self-contained navigation has a characteristic that it is possible to accurately obtain the current position, but on the other hand, there is a possibility that the current position is greatly erroneous. On the other hand, according to radio navigation, it is not possible to expect exact determination of the current position, but there is a characteristic that the current position will not be greatly mistaken.

Therefore, the present invention considers the characteristics of the radio navigation and the self-contained navigation and interpolates each other, and can always determine the current position with a certain level of reliability. The purpose is to provide.

[0010]

[Means for Solving the Problems] To achieve the above object,
The present invention is, for example, a navigation device which is mounted on a moving body and outputs the current position of the moving body, and which is an azimuth measuring means for measuring the traveling azimuth of the moving body based on at least one of an angular velocity and a geomagnetic angle. A distance measuring means for measuring the traveling distance of the moving body, a storing means for storing road map information, a current position determined last time, a traveling azimuth measured by the azimuth measuring means, and a travel measured by the distance measuring means. The self-contained navigation means for determining the first provisional current position of the moving body based on the distance, the first provisional present position, or the first provisional present position and traveling direction in the storage means. The stored road map information within the search range provided around the first provisional current position is collated, and the position on the road having the highest degree of matching with this is set as the second provisional current position. The degree of matching Map matching means as a reliability, radio navigation means for obtaining a third provisional current position of the moving body based on radio waves from a plurality of artificial satellites, and when the reliability is smaller than a certain value, the third Current position selecting means for determining the temporary current position as the final current position, and for determining the second temporary current position as the final current position when the reliability is higher than a certain value. To provide a navigation device that does.

[0011]

According to the above-described navigation device of the present invention, when the reliability of the second provisional current position obtained by the self-contained navigation means and the map collating means is smaller than a certain value, the navigation method obtained by radio navigation is used. The third temporary current position is determined as the final current position, and the second temporary current position is determined as the final current position when the reliability is higher than a certain value.

That is, when it is estimated that the current position is accurately obtained by the self-contained navigation and the map collating means, the current position obtained by the self-contained navigation capable of accurately obtaining the current position by radio navigation is used. If it is presumed that a greatly incorrect current position has been obtained, the current position obtained by radio navigation that does not cause a large error in the current position is determined as the current position.

Therefore, the current position can always be obtained with a certain level of reliability.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the navigation device according to the present invention will be described below.

FIG. 1 shows the configuration of the navigation system according to this embodiment.

In the figure, reference numeral 202 denotes an angular velocity sensor such as a gyro device or a geomagnetic angle sensor such as a geomagnetic sensor. In this embodiment, an optical fiber gyro will be used. The optical fiber gyro 202 is installed so as to detect the yaw rate of the vehicle. A vehicle speed sensor 203 outputs a pulse in proportion to the rotation of the transmission. Reference numeral 204 denotes an antenna that receives radio waves from GPS satellites, and 205 processes a signal received by the antenna 204 to obtain a vehicle position, azimuth, speed, and DOP value (an index of position accuracy determined by a satellite arrangement state). It is an output GPS receiver.

Reference numeral 206 denotes a switch for instructing switching of the scale of the map displayed by the user (driver). 20
Reference numeral 7 is a CD-ROM for storing road map information in digital form, and 208 is a CD-ROM 20.
7 is a driver for reading the road map information stored in FIG.

Reference numeral 210 denotes a controller, which outputs the output values of the optical fiber gyro 202, the vehicle speed sensor 203, the GPS receiver 205, and the CD-ROM 207 to the driver 2
It is a controller that determines the current position according to the map information read via 08. 209 is a display. As shown in FIG. 2, it is a display for displaying a map around the current position determined by the navigation device under the control of the controller 210, a mark indicating the current position, and the like.

Further, in the controller 210, 211 is an A / D converter for converting a gyro signal (analog signal) into a digital signal, 217 is a counter for counting the number of pulses of the vehicle speed sensor every 0.1 seconds, 218. Is GPS
Serial interface for receiving receiver data, 2
12 is a parallel I / O for recognizing the pressed switch, 215 is a microprocessor, 216 is a memory, 2
Reference numeral 13 is a DMA controller that transfers the read map data to the memory 216, and reference numeral 214 is a display processor that controls the display on the display 209.

In such a configuration, the A / D converter 2
11, parallel I / O 212, DMA controller 21
3, the input signal obtained from the counter 217 and the serial interface 218 is processed by the microprocessor 215, and the position is notified to the user by issuing a command to the display processor 214 to realize the display shown in FIG.

The memory 216 includes a ROM that stores a program that implements the processing described below, and a RAM that is used as a work area when the microprocessor 215 performs the processing.

The operation of determining the current position performed by the navigation system according to this embodiment will be described below.

The microprocessor 215 according to the present embodiment.
Performs three processes of azimuth, distance calculation process, current position determination process, and display process.

First, the azimuth and distance calculation processing will be described.

This processing is started and executed every 100 milliseconds by a timer interrupt by a timer in the microprocessor 215.

FIG. 3 shows the procedure of the azimuth and distance calculation processing.

As shown, in this process, first, A
The output value of the optical fiber gyro 202 is read from the / D converter 211 (401). Here, the output value of the optical fiber gyro 202 indicates a change in direction. Next, the position, direction, speed, and DOP value calculated by the GPS receiver are read from the serial interface 218 (402), and the estimated direction is calculated from this GPS direction and the output of the optical fiber gyro 202 (403).

In this calculation, for example, when the radio wave from the GPS satellite can be received, the GPS azimuth is set as the estimated azimuth as it is, and when the GPS cannot be received, the output of the optical fiber gyro 202 is added to the previous estimated azimuth. The calculated value is used as the estimated bearing. Alternatively, since the GPS azimuth has a large error when the vehicle speed is low, the GPS azimuth is used only when the vehicle speed is constant or higher. In other cases, the value obtained by adding the output of the optical fiber gyro 202 to the previous estimated azimuth is used. May be set.

Next, the number of pulses for 0.1 second output from the vehicle speed sensor is read from the counter 217 (40
4). Then, by multiplying this value by the traveling distance constant per one rotation of the tire, the traveling distance in 0.1 second is obtained (405). Then, when this value is integrated and 10 m is advanced, the azimuth and distance (10 m) at that time are written in the memory 216 (406), and the process is terminated.

Next, the current position determination process will be described.

This process is started and executed each time the azimuth / distance calculation process is completed, that is, each time the distance is advanced by 10 m.

FIG. 4 shows the procedure of the current position determination processing.

As shown in the figure, in this processing, first, the heading and the heading and the heading calculated by the distance calculation processing are read from the memory 216 (501), and the movement amount is separately calculated in the latitude and longitude directions, and this is calculated. The temporary current position (A) is obtained by adding to the previously determined current position (502). In addition, at the time of initial operation, if the previously determined current position does not exist, the position obtained by the GPS receiver 205 is set as the previously determined current position.

Next, the temporary present position (A) is collated with the road map to correct the temporary present position (A).

That is, a map around the provisional current position (A) is read from the CD-ROM 207 via the driver 208, and a search range is a range within a predetermined distance with each current position (A) as the center. Extract roads in D (50
3). How to determine the predetermined range will be described later. Here, each road is represented by connecting straight lines (links) in the road map information. Specifically, as shown in FIG. 6, the road is represented in the road map information as coordinates of both ends (nodes) of a plurality of straight lines set on the road.

Next, from the extracted roads, only the links whose extending directions are within a predetermined value with the advancing direction are extracted (504), and the provisional current position (A) for all these line segments is extracted. Lower the vertical line. Then, the length of the perpendicular is obtained, and the reliability is calculated in accordance with the reliability = 1 / (α × | traveling azimuth−line segment azimuth | + β × | vertical length |). However, α and β are weighting factors, and α + β = 1. In addition, α is increased when a road with a small difference in direction is emphasized, and β is increased when a road with a short distance is emphasized.

Then, the link with the highest degree of reliability is selected, and the foot of the perpendicular drawn to the link is set as the corrected provisional current position (B) (506).

Next, the microprocessor 205 determines that the GP
The position and DOP obtained by the GPS receiver 202 obtained from the S receiver 205 through the serial interface 218.
The value of is read (508). And the GPS receiver 20
The position obtained by 2 is set as the provisional current position (c). Where D
OP is a parameter determined by the arrangement state of GPS satellites and correlates with GPS position accuracy. Here, DOP
HDOP, which is a parameter related to the horizontal direction of, is used.

Next, the obtained HDOP and the reliability value of the link with the highest reliability in the previous processing are examined, and one of the temporary current position (B) and the temporary current position (C) is finally determined. A current position (D) is set (509).

Now, according to the self-contained navigation, there is a possibility that the current position can be calculated more accurately than the radio navigation, but
Once the current position is incorrect, the calculated difference between the calculated current position and the true current position may become larger and larger. If the provisional current position (B) calculated by self-contained navigation is likely to be incorrect, the search range D
If the search range D is widened, the possibility of returning to the correct position by the self-contained navigation is increased. However, if the search range D is widened, the processing amount is also increased, and therefore the search range D cannot be expanded indefinitely. On the other hand, according to the radio navigation, it is more difficult to calculate the current position more accurately than the self-contained navigation, but the position is not greatly mistaken.

Therefore, in this embodiment, the provisional current position (B) and the provisional present position (C) normally calculated by the self-contained navigation are selected as the final present position (D), and the provisional current calculated by the self-contained navigation is selected. When there is a high possibility that the position (B) is incorrect, the provisional current position (C) is selected as the final current position (D).

That is, for example, when the reliability is less than a predetermined value, the position obtained by the GPS receiver 202, that is, the provisional current position (C) is unconditionally set as the final current position (D).

Alternatively, the HDOP may be compared with the reliability, and the more probable one of the provisional current position (B) and the provisional current position (C) may be set as the final current position (D). .

Alternatively, since the temporary current position (A) or the distance between the temporary current position (B) and the temporary current position (C) represents the unreliability of the temporary current position (A) or the temporary current position (B), The reliability is compared with the reliability that is obtained by multiplying the distance between the temporary current position (A) or the temporary current position (B) and the temporary current position (C) by an appropriate constant, and the reliability is compared. Is larger, the provisional current position (C) is set as the final current position (D).

Alternatively, the predetermined distance defining the size of the search range D used to obtain the provisional current position (B) is
When the distance between the temporary current position (A) or the temporary current position (B) and the temporary current position (C) exceeds, the temporary current position (C) is set as the final current position (D). In this case, it is highly possible that the true current position was outside the search range D used for obtaining the provisional current position (B).

Alternatively, the predetermined distance that determines the size of the search range D used to obtain the next temporary current position (B) is set to the temporary current position (A) or the temporary current position (B) and the temporary current position ( When the distance from C) is exceeded, the provisional current position (C) is set as the final current position (D). In this case, the provisional current position (B) is highly likely to be in the wrong position by being larger than the size of the next search range, and in this case, there is a high possibility that the self-contained navigation cannot return to the calculation of the correct position. Because.

Alternatively, further, when the error distance is estimated from the HDOP and the estimated error distance exceeds the predetermined distance which defines the size of the search range D used for obtaining the provisional current position (B). The provisional current position (C) may be set as the final current position (D). The true current position is
This is because it is not possible to obtain confirmation that the search range D used to obtain the provisional current position (B) was present. If the estimated error distance exceeds the predetermined distance that determines the size of the search range D used to obtain the next temporary current position (B), the temporary current position (C) is finally determined. The current position (D) may be set. Temporary current position (B)
However, it is not possible to obtain confirmation that the position is not larger than the size of the next search range.

Then, the final present position (D) determined thereafter is output (510).

Here, how to obtain the above-mentioned search range D will be described.

The search range D may be a range within a predetermined fixed distance centered on each current position (A), but the previous provisional current value ( B) The range may be within the distance determined based on the reliability used for obtaining.

That is, as shown in FIG. 6, when the reliability is low, it is considered that the error in the measurement value of the self-contained navigation is large. Therefore, a wider range is searched for the road.

Next, details of the display processing will be described.

This processing is started and executed every one second by a timer interrupt by a timer in the microprocessor 215.

FIG. 5 shows the procedure of display processing.

In this process, as shown in FIG. 2, the final current position (D) determined in the current position determination process is displayed on the display 209 together with the map.

That is, first, the state of the switch 206 is judged by looking at the contents of the parallel I / O 212 (60).
1).

If the switch is in the state of instructing the switching of the scale, the scale flag is switched according to the contents of the instruction (602). Next, the final current position (D) is read (603), the map information of the range including the final current position (D) is read from the CD-ROM 207 via the driver 208, and this is used as the content of the scale flag. In order to display a map of a scale corresponding to the range including the final current position (D) on the display 209,
The display processor 214 is instructed (604).

Then, the traveling direction of the vehicle is shown in FIG. 2 at the position corresponding to the final current position (D) on the displayed map.
The display processor 214 is instructed to display the same on the display 209 as in ↑ ((605). Finally, the display processor 214 displays the north mark and the distance mark on the display 209 so as to be overlapped as shown in FIG. (606).

[0059]

As described above, according to the present invention, the current position can always be determined with a certain level of reliability while mutually interpolating between such radio navigation and self-contained navigation. It is possible to provide a navigation device capable of performing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a navigation device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a display example performed by the navigation device according to the embodiment of the present invention.

FIG. 3 is a flowchart showing a processing procedure of an azimuth and distance calculation processing according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a processing procedure of a current position determination processing according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a processing procedure of display processing according to the embodiment of the present invention.

FIG. 6 is a diagram showing a representation method of roads in road map information.

[Explanation of symbols]

 202 optical fiber gyro 203 vehicle speed sensor 204 antenna 205 GPS receiver 206 switch 207 CD-ROM 208 driver 209 display 210 controller

Claims (6)

[Claims] 1. A navigation device mounted on a mobile body, for outputting the current position of the mobile body, comprising: azimuth measuring means for measuring the traveling azimuth of the mobile body based on at least one of an angular velocity and a geomagnetic angle. , A distance measuring means for measuring the traveling distance of the moving body, a storage means for storing road map information, a current position determined last time, a traveling azimuth measured by the azimuth measuring means, and a traveling distance measured by the distance measuring means Self-contained navigation means for determining a first temporary current position of the moving body based on the above, and the first temporary current position, or the first temporary current position and the heading, are stored in the storage means. The road map information within the search range provided around the first provisional current position is collated, and the position on the road having the highest degree of matching with the road map information is set as the second provisional current position. Trust the degree of matching And a radio navigation means for determining a third provisional current position of the mobile body based on radio waves from a plurality of artificial satellites, and the third provisional current if the reliability is smaller than a certain value. And a current position selecting unit that determines a position as a final current position and determines the second temporary current position as a final current position when the reliability is higher than a certain value. apparatus. 2. A navigation device mounted on a mobile body, for outputting the current position of the mobile body, comprising: azimuth measuring means for measuring a traveling azimuth of the mobile body based on at least one of an angular velocity and a geomagnetic angle. , A distance measuring means for measuring the traveling distance of the moving body, a storage means for storing road map information, a current position determined last time, a traveling azimuth measured by the azimuth measuring means, and a traveling distance measured by the distance measuring means Self-contained navigation means for determining a first temporary current position of the moving body based on the above, and the first temporary current position, or the first temporary current position and the heading, are stored in the storage means. The road map information within the search range provided around the first provisional current position is collated, and the position on the road having the highest degree of matching with the road map information is set as the second provisional current position. Trust the degree of matching And a radio wave that determines the third provisional current position of the moving body based on radio waves from a plurality of artificial satellites and the accuracy of the third provisional current position from the arrangement state of the plurality of artificial satellites. A navigation means is used to compare the reliability and the accuracy, and a current position selection for determining the more probable one of the second current position and the third provisional current position as the final current position as the current position is selected. And a navigation device. 3. A navigation device which is mounted on a moving body and outputs the current position of the moving body, the direction measuring means for measuring a traveling direction of the moving body based on at least one of an angular velocity and a geomagnetic angle. , A distance measuring means for measuring the traveling distance of the moving body, a storage means for storing road map information, a current position determined last time, a traveling azimuth measured by the azimuth measuring means, and a traveling distance measured by the distance measuring means Self-contained navigation means for determining a first temporary current position of the moving body based on the above, and the first temporary current position, or the first temporary current position and the heading, are stored in the storage means. The road map information within the search range, which is a range within a certain distance centered on the first provisional current position, is matched, and the position on the road having the highest degree of matching with this is used as the second provisional position. Map matching with current position A step, a radio navigation means for obtaining a third provisional current position of the moving body based on radio waves from a plurality of artificial satellites, the first provisional present position or the second provisional present position, and the third provisional present position. A distance from the temporary current position is calculated, and when the calculated distance is larger than the predetermined distance that determines the size of the search range, the third temporary current position is determined as the final current position. A navigation device comprising: a third temporary current position and a current position selecting means for determining the final current position. 4. A navigation device which is mounted on a moving body and outputs the current position of the moving body, the direction measuring means for measuring the traveling direction of the moving body based on at least one of angular velocity and geomagnetic angle. , A distance measuring means for measuring the traveling distance of the moving body, a storage means for storing road map information, a current position determined last time, a traveling azimuth measured by the azimuth measuring means, and a traveling distance measured by the distance measuring means Self-contained navigation means for determining the first provisional current position of the mobile body, and the size of the search distance based on the above, and the first provisional present position or the advance with the first provisional present position. The orientation and the road map information stored in the storage means are compared with the road map information within the search range, which is a range within the search distance centered on the first provisional current position, and the degree of matching is highest. Second position on the road Map matching means for determining the current position and reliability of the degree of matching, radio navigation means for determining a third provisional current position of the mobile body based on radio waves from a plurality of artificial satellites; If the distance between the first temporary current position or the second temporary current position and the third temporary current position is found, and if the found distance is larger than the search distance, the third temporary current position is finalized. A current position determining unit that determines the third temporary current position as the final current position when the current temporary position is determined as the final current position. A navigation device characterized in that the size of the search distance is determined according to the reliability of the position. 5. A navigation device which is mounted on a moving body and outputs the current position of the moving body, the direction measuring means for measuring the traveling direction of the moving body based on at least one of an angular velocity and a geomagnetic angle. , A distance measuring means for measuring the traveling distance of the moving body, a storage means for storing road map information, a current position determined last time, a traveling azimuth measured by the azimuth measuring means, and a traveling distance measured by the distance measuring means Self-contained navigation means for determining a first temporary current position of the moving body based on the above, and the first temporary current position, or the first temporary current position and the heading, are stored in the storage means. The road map information within the search range, which is a range within the search distance centered on the first provisional current position, is collated, and the position on the road having the highest degree of matching with this is used as the second provisional position. The current position and Map matching means having the degree of matching as the degree of reliability, search distance updating means for updating the degree of the next search distance according to the degree of reliability, and a mobile unit based on radio waves from a plurality of artificial satellites. A radio navigation means for obtaining a third temporary current position, a distance between the first temporary current position or the second temporary current position and the third temporary current position is obtained, and the obtained distance is updated. And a current position determining means that determines the third temporary current position as the final current position when it is larger than the search distance, and determines the third temporary current position as the final current position when it is smaller. A navigation device characterized by having. 6. The navigation device according to claim 1, 2, 3, 4 or 5, wherein the radio navigation means comprises a plurality of GPSs (Global Positioni).
ng System) A navigation device characterized by being a GPS receiver that obtains a third provisional current position of a moving body based on radio waves from a satellite.