JP3263437B2 - Vehicle navigation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to global positioning.
The present invention relates to a vehicular navigation device using both System (hereinafter abbreviated as “GPS”) and self-contained navigation.

[0002]

2. Description of the Related Art Hitherto, navigation devices using both GPS satellite navigation and self-contained navigation have been put into practical use. By comparing and judging the calculation results of measurement data obtained by each navigation, a more reliable autonomous navigation system has been developed. Car position is being measured.

[0003] In satellite navigation, radio waves emitted from three or more GPS satellites are received and analyzed to calculate the position of each satellite and the distance from each satellite to the host vehicle. The self-contained navigation is a dead reckoning navigation that calculates the position of the own vehicle at the time from the moving speed and the moving direction of the own vehicle with the origin position as a starting point.

FIG. 5 is a block diagram illustrating a navigation device using both self-contained navigation and satellite navigation. The navigation device includes a map data storage unit 1 for storing map data, a self-contained navigation means 2 for detecting a position of the own vehicle based on a sensor signal, a GPS receiving unit 3, a map and a position of the own vehicle. Display 4 and a drive circuit 5 for the display.

In addition, the map data storage unit 1, the self-contained navigation means 2, the GPS receiving unit 3, and the driving circuit 5 are controlled in accordance with a program recorded on a CD-ROM, and the display unit 4 is used for the purpose. A main microcomputer (Main-Microcomputer) 6 for displaying a map and the position of the host vehicle is provided. This main microcomputer 6 has an operation switch 7
, The operation of the navigation device is performed. Communication between the map data storage unit 1, the self-contained navigation means 2, the GPS receiving unit 3, and the main microcomputer 6 is performed by a communication bus 8.

In this device, when map data is accessed from the main microcomputer 6, the map information recorded on the CD-ROM 10 is converted by the decoder 11 under the control of the CD-ROM control microcomputer 9 for managing access to the map data. And transmitted on the communication bus 8 to be displayed on the display 4.

The self-contained navigation means 2 detects the traveling speed of the vehicle with the wheel speed sensor 12 and detects the traveling direction of the vehicle with the geomagnetic sensor 13. Then, the moving direction and the moving distance from the starting position, which is the origin position, are calculated by integrating them over time. This calculation is performed by the self-contained navigation calculation microcomputer 14.

The result of the calculation is periodically (for example, 1 second) transmitted to the communication bus 8 to update the position of the host vehicle. That is, the main microcomputer 6 receives the calculation result indicating the own vehicle position, and displays the own vehicle position on the map displayed on the display unit 4.

On the other hand, the GPS receives a radio wave from three or more GPS satellites 15 orbiting the earth in a predetermined orbit by the GPS receiving unit 3 and analyzes it to calculate the position of the vehicle. It is.

As shown in FIG. 6, the conventional GPS receiving section calculates the current vehicle position (X ₁ , X ₁ ,
After calculating Y ₁ ), a predetermined time (for example, about 1 second)
The current position (X ₂ , Y ₂ ) at time t2 after elapse of is calculated. Then, from the coordinates of the two positioning points, a traveling vector of the own vehicle is calculated, a traveling direction and a traveling distance are obtained,
For example, the data is transmitted to the communication bus 8 at a cycle of 1 second, and
It is used for updating the own vehicle position above.

[0011] By the way, when the vehicle is traveling in a tunnel or the like or in a building, and the GPS satellite radio wave cannot be received, a method of switching to the self-contained navigation is adopted. In addition, in the self-contained navigation, since measurement errors are accumulated, the measurement result by the satellite navigation is compared with the measurement result by the self-contained navigation, and the reliability of each navigation is determined based on whether or not they match.

FIG. 7 is a flowchart illustrating a conventional navigation selection system, which is executed by the main microcomputer 6 according to a program recorded in advance on a CD-ROM. As described above, the calculation result by the satellite navigation in the GPS receiving unit 3 is transmitted to the communication bus 8 at a cycle of 1 second, and the measurement position is updated.

Step S1 in this flowchart
In the case where it is determined that the update of the measurement position is not performed, as in the case of entering a tunnel or the like, it is a case where radio waves cannot be received and satellite navigation cannot be adopted, In that case, in step S2, the mode is switched to the self-contained navigation by the self-contained navigation means 2 in FIG. 5, and the self-vehicle position is measured by the self-contained navigation. If it is determined in step S1 that the measurement position has been updated by satellite navigation, then in step S3, a travel vector is calculated using satellite navigation. That is, as shown in FIG. 6, the traveling vector of the host vehicle is calculated from the coordinates of the two positioning points before and after the predetermined time, and the traveling direction and the traveling distance are obtained.

Then, in step S4, a comparison is made between the travel vector obtained by the two satellite navigation measurements and the travel vector obtained by dead reckoning between them. If the two traveling vectors match, any navigation is determined to be normal, and one of the navigations is adopted. Normally, step S5
In, the measurement result by satellite navigation is adopted. If they do not match, use one of the more reliable navigations. For example, in step S6, self-contained navigation is adopted.

[0015]

However, the conventional method of calculating the traveling vector of the own vehicle from the coordinates of the two positioning points before and after the predetermined time measures the next position unless the predetermined time is elapsed. Can not. Therefore, a waiting time is required until the position of the own vehicle is obtained, which is inefficient. Also,
The utilization efficiency of the main microcomputer 6 also decreases.

On the other hand, if it is determined in step S4 in FIG. 7 that the measurement results obtained by the two navigations do not match, it is difficult to determine which navigation caused the measurement error. It was difficult to decide.

That is, if it is determined in step S4 of FIG. 7 that the speed vectors of the two navigations do not match, the positioning result of the self-contained navigation is to be adopted in step S6. Since there is a possibility that there is a mismatch, the processing in FIG. 7 cannot be said to have made an accurate determination.

The technical problem of the present invention is to pay attention to such a problem, to be able to efficiently measure the position of the vehicle by satellite navigation without waiting time, and to receive radio waves from satellites. Even in such cases, it is possible to accurately determine the reliability of the satellite navigation measurement, and if an error occurs in the satellite navigation, switch to self-contained navigation.
An object of the present invention is to make it possible to measure the current position of the own vehicle with higher accuracy.

[0019]

FIG. 1 is a block diagram illustrating a basic configuration of a vehicle navigation system according to the present invention. As shown in this figure, the vehicle navigation device of the present invention uses a Doppler shift of a radio wave received from a GPS satellite to calculate a speed vector (including speed and direction components) of the own vehicle. And self-contained navigation means 2 for calculating a traveling vector of the own vehicle based on signals obtained from various sensors mounted on the own vehicle.

[0020]

According to the present invention, in the above navigation apparatus, when the magnitude of the vertical component of the velocity vector of the own vehicle obtained from the GPS receiving unit 3 exceeds a certain value, the measurement result by the satellite navigation becomes This is a configuration including a control unit 6 that determines that an error has occurred.

[0022]

The vehicle navigation system of the present invention uses both satellite navigation and self-contained navigation. In satellite navigation, the frequency of satellite radio waves fluctuates due to the Doppler effect because GPS satellites move in orbit at high speed (this is called "Doppler shift").
). Therefore, in the GPS navigation, not only the position information of the latitude, the longitude, and the altitude but also the direction and the speed at which the own vehicle is moving can be calculated from the frequency change of the radio wave received from the GPS satellite.

That is, as shown in FIG. 2, a radio wave is received from a GPS satellite, three-dimensional positioning is performed, and a speed vector V of the own vehicle is calculated. This velocity vector V can be divided into north, east, and upward components, and the north component
The horizontal component Vh is obtained by combining Vn and the east component Ve. The upward component Vv is defined as a vertical component.

[0024]

[0025]

The present invention relates to a method for judging whether or not the measurement result by satellite navigation is correct. When the positioning position of the own vehicle can be updated by satellite navigation, the velocity vector using the Doppler shift is updated. Vertical component Vv
Is larger than a certain value, it is determined that there is an error in the calculation result by satellite navigation.

That is, when the vehicle is traveling normally, the position in the vertical direction cannot change greatly in a short time. Therefore, when the vertical component of the velocity vector abnormally increases, it is assumed that an abnormality has occurred for some reason in the satellite navigation. As described above, when the vertical component Vv is abnormal, the value of the horizontal component Vh is also incorrect, and thus cannot be adopted as position information.

As described above, by performing positioning using the Doppler shift and determining the vertical component Vv of the velocity vector, it is possible to accurately determine an abnormality in the satellite navigation, so that it is easy to determine the next navigation to be adopted. Become. For example, when it is determined that there is an abnormality, it is possible to switch to the self-contained navigation, perform more accurate positioning, and measure the current position of the own vehicle with higher accuracy.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a practical embodiment of a vehicle navigation device according to the present invention will be described with reference to an embodiment. The navigation apparatus for a vehicle according to the present invention includes the self-contained navigation means 2 and the GPS in the navigation apparatus shown in FIG.
This is realized by applying the self-contained navigation means 2, GPS receiving section 3 and control means 6 shown in FIG. 1 to the receiving section 3 and the main microcomputer 6.

FIG. 3 is a flowchart illustrating a control program of the main microcomputer 6. First, FIG.
It is determined in step S1 in FIG. 3 whether the positioning data is transmitted from the GPS receiving unit 3 to the main microcomputer 6 at a fixed cycle and the data is updated. The satellite navigation in the present invention uses Doppler navigation using Doppler shift.

As a case where the position information is not updated by the satellite navigation, there may be a case where it is impossible to receive a radio wave from a satellite due to entering a tunnel, a building shadow, or the like. In such a case, satellite navigation cannot be used, so switch to self-contained navigation as shown in step S2,
The position information is updated using the position information from the self-contained navigation means 2 shown in FIG.

If it is determined in step S1 that the positioning data by satellite navigation has been updated,
In S3, positioning at the next positioning point is performed. That is, the GPS receiver 3 obtains the velocity vector V shown in FIG. 2 by using the above-described Doppler shift method.
Next, in step S4, the horizontal component Vh of the velocity vector V is determined. This is the traveling vector of the own vehicle obtained by the Doppler shift method. Unlike the conventional measurement method shown in FIG. 6, only the positioning at one point is sufficient.

Next, the traveling vector Vh calculated by the Doppler shift method is compared with the traveling vector transmitted from the self-contained navigation means 2 in step S5, and it is determined whether both traveling vectors match.

If the result of this comparison is that they match,
If they do not match, the post-processing is optional, and various processing can be considered. In the case of coincidence or non-coincidence, it is optional to adopt satellite navigation or self-contained navigation.

For example, if they match, step S6
In, the position data is updated by adopting the positioning data by satellite navigation, and the process returns to step S1. Alternatively, the result of the self-contained navigation may be adopted instead of the satellite navigation, or the determination based on other factors may be performed.

In the case of a mismatch, in step S7, the position data may be updated by using positioning data by self-contained navigation, or a result by satellite navigation may be used instead of self-contained navigation. Alternatively, the determination may be made based on other following factors.

As described above, in this embodiment, since the Doppler navigation is used as the satellite navigation, the position, the traveling direction, and the traveling speed of the own vehicle can be calculated by one positioning. Also,
According to the Doppler shift method, the vertical movement component of the own vehicle can also be calculated, so that the presence or absence of a satellite navigation positioning error is determined based on the magnitude of the vertical movement component as shown in the next embodiment. Can also.

FIG. 4 is a flowchart showing an embodiment of the present invention, which is applied to a control program of the main microcomputer 6. That is, the positioning data by the Doppler navigation is transmitted from the GPS receiving unit 3 to the main microcomputer 6 in a fixed cycle in FIG. 5, and it is determined in step S1 whether the positioning data is updated.

In the tunnel or in the shadow of a building,
As in the case where the radio wave from the satellite cannot be received,
If the location information is not updated by satellite navigation,
In step S5, the positioning data by the self-contained navigation is transmitted from the self-contained navigation means 2 of FIG. 5 to the main microcomputer 6, and the position data is updated.

If it is determined in step S1 that the positioning data by satellite navigation has been updated, it is determined that satellite navigation can be continued, and positioning is performed at the next positioning point in step S2. That is, the GPS receiver 3 obtains the velocity vector V shown in FIG. 2 by using the above-described Doppler shift method.

Then, a vertical component Vv is obtained from the velocity vector V. The vertical component Vv is the amount of movement of the host vehicle in the vertical direction, and is extremely small in normal traveling. Therefore, when the vertical component Vv is abnormally large, it is assumed that an abnormality has occurred in the satellite navigation for some reason and the positioning data cannot be used.

Therefore, in step S3, the vertical component Vv of the velocity vector V calculated by the Doppler shift method
Is smaller than a predetermined value α, it is determined that there is no abnormality in the satellite navigation. In step S4, the positioning result by the satellite navigation is adopted, and the positioning data is transmitted from the GPS receiver 3 to the main microcomputer 6. Then, the positioning data is updated. Alternatively, a determination process based on the following factors may be performed.

On the other hand, if the vertical component Vv of the velocity vector V is larger than the fixed value α, it is considered that an abnormality has occurred in the satellite navigation, and the positioning data of the satellite navigation is not used, and the positioning data of the self-contained navigation is not used. Is transmitted from the self-contained navigation means 2 to the main microcomputer 6 to update the positioning data.

Thereafter, by repeating the steps after "determining whether or not the positioning data is updated by the satellite navigation" in step S1, the error determination of the satellite navigation based on the magnitude of the vertical component Vv of the velocity vector always obtained by the Doppler shift method is repeated. repeat. Therefore, it is possible to accurately determine whether the positioning result of the satellite navigation is correct or not, and to accurately switch to the self-contained navigation.

For example, the processing of steps S2 to S5 in FIG. 4 is inserted between steps S5 and S7 in FIG.
If it is determined that “v> α”, it is possible to accurately detect that the cause of the mismatch in step S5 in FIG. 3 is satellite navigation.

Therefore, thereafter, if the self-contained navigation is adopted in step S5, accurate positioning can be performed. If it is determined in step S3 that "the vertical component of the velocity vector Vv <α", it can be accurately detected that the cause of the mismatch in step S5 in FIG. 3 is the self-contained navigation.
If the satellite navigation is adopted, accurate positioning becomes possible.

[0047]

According to the navigation device of the present invention, the radio wave from the GPS satellite can be received, and even if the positioning data is updated, the satellite navigation can be performed from the vertical component Vv of the velocity vector obtained by the Doppler shift method. Can determine the reliability of the positioning results, so that it is possible to accurately detect abnormalities in the calculation results by satellite navigation, and when it is determined to be abnormal, automatically switch to self-contained navigation to detect the position of the vehicle with high accuracy. Can do it.

[0048]

[Brief description of the drawings]

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

FIG. 2 is a diagram showing a velocity vector and its horizontal and vertical components in the Doppler shift method.

FIG. 3 is a flowchart showing a control program of a main microcomputer 6;

FIG. 4 is a flowchart showing a control program of the present invention.

FIG. 5 is a block diagram showing an outline of a conventional vehicle navigation device.

FIG. 6 is a diagram showing a positioning method in the conventional satellite navigation.

FIG. 7 is a flowchart showing a navigation processing procedure in a conventional vehicle navigation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Map data storage part 2 Self-contained navigation means 3 GPS receiving part 4 Display 5 Drive circuit 6 Main microcomputer (Control means) 7 Operation switch 8 Communication bus 9 CD-ROM control microcomputer 10 CD-ROM 11 Decoder 12 Wheel speed sensor 13 Geomagnetism Sensor 14 Independent navigation calculation microcomputer 15 GPS satellite

Claims (1)

(57) [Claims] A GPS receiver for calculating a speed vector of the vehicle based on a signal received from a GPS satellite; and a self-supporting device for calculating a position of the vehicle based on a signal obtained from a sensor mounted on the vehicle. If the magnitude of the vertical component of the speed vector of the own vehicle obtained by the navigation means (2) and the GPS receiver (3) exceeds a certain value, it is determined that the measurement result by the satellite navigation is an error. Control means
(6) A vehicle navigation device, comprising: