JPH0777571A - On-vehicle navigation system - Google Patents

Abstract

PURPOSE:To make it possible to calculate the altitude of a vehicle even when four satellites can not be captured, by providing a first means for operating the position of vehicle, and a second means for operating the position of vehicle based on the GPS signals from a plurality of satellites. CONSTITUTION:A processing section 8 comprising a microcomputer and the peripheral equipment specifies the position of a vehicle based on a position operated by self-contained navigation based on a running distance detected based on a pulse signal from a vehicle speed sensor 3, a running direction detected by an angular speed sensor 4 and a geomagnetic sensor, and a road map data around the vehicle read out from a CD-ROM 6, and a position operated by a CPS receiver 1. Since map matching is effected and the altitude of vehicle is operated based on GPS signals from more than one satellites and a vehicle position calculated by self-contained navigation, altitude of vehicle can be calculated without increasing the volume of road map data even when four satellites cannot be captured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle-mounted navigation device for displaying the position of a vehicle on a road map and guiding an occupant to a destination.

[0002]

2. Description of the Related Art GPS (Global Position)
The position of the vehicle is detected by the Ning System),
There is known a vehicle-mounted navigation device that is displayed on a road map to guide an occupant to a destination.

Here, a method of detecting the vehicle position by GPS will be described. In the following, detection of the vehicle position by GPS is called GPS positioning, and the detected position data is GPS
Called positioning data.

The GPS signal sent from the satellite includes orbit data indicating the position of each satellite, time data indicating the correct time, accuracy data indicating the accuracy of the GPS signal itself, and the like. The GPS receiver solves the Kepler's equation based on the orbital data and determines the satellite position (Xi, Yi, Z
i) is calculated.

The positioning coordinate system of GPS is W worldwide.
Established according to the GS84 standard, the center of the earth (centricity)
The origin is a Cartesian coordinate, and the direction from the earth center to the pole is the Z axis, and the direction from the earth center to the average equinox on the average equatorial plane is the X axis. In Japan, the GPS coordinate system is further converted into the Japanese geodetic system (TOKYO DATUM) to perform GPS positioning calculation.

Next, the distance Ri from each satellite to the receiving point (vehicle position) is measured by the radio wave propagation time. GPS signals are synchronized to GPS system time,
If the receiver has an accurate clock, the propagation time of radio waves can be measured. Actually, it is difficult to equip the GPS receiver with an accurate clock, and assuming that the clock of the receiver is deviated from the GPS system time by Δtu, the measured distance Ri from the satellite to the reception point is Is the unknown Δtu
Will be included.

When the distance Ri from the satellite to the receiving point can be measured, the position of the receiving point (vehicle position) (Xu, Yu, Zu)
And an equation in which Δtu included in the distance Ri is an unknown number can be set.

[Number 1] ^{(Xi-Xu) 2 + (} Yi-Yu) 2 + (Zi-Zu) 2 = Ri 2 ··· (1) i in this equation contains four unknowns, solving this = 1 to 4 equations are required. That is,
The position of each satellite (Xi,
Yi, Zi) and the distance Ri from each satellite to the receiving point are calculated and substituted into the equation (1) to form four simultaneous equations to obtain the position (Xu, Yu, Zu) of the receiving point.

However, if the signal radio waves from the satellites are blocked by buildings or the like so that the signal radio waves can be received from only three satellites, only three simultaneous equations (1) can be established, so two-dimensional (Xu, Yu) Only the positioning is possible, and the altitude Z of the vehicle
There is a problem that u cannot be calculated.

In order to solve this problem, a navigation device having road map data including altitude information of the vehicle has been proposed (for example, Japanese Patent Laid-Open No. 62-26108).
(See Japanese Patent No. 7). In this device, road map data including altitude information of the vehicle is stored, and when only three satellites can be captured due to obstacles such as buildings, the position of the vehicle ( Xu, Yu) and referring to the road map data, the altitude Zu of the vehicle at that position
To search. Next, the altitude Zu of this vehicle is substituted into the simultaneous equations described above to perform recalculation, and the accurate vehicle position (X
u, Yu, Zu).

[0010]

However, in the above-described conventional vehicle-mounted navigation device, since the road map data must include the altitude information of the vehicle, the amount of data increases and unregistered points such as new roads. There is a problem that the altitude information of the vehicle cannot be obtained.

An object of the present invention is to provide a vehicle-mounted navigation device capable of calculating the altitude of a vehicle without increasing the amount of road map data even when it cannot capture four satellites.

[0012]

The present invention will be described with reference to FIG. 1, which is a claim correspondence diagram, and the present invention detects a traveling distance of a vehicle and a traveling direction of the vehicle. Direction detecting means 101, storage means 102 for storing road map data, traveling distance detected by distance detecting means 100, traveling direction detected by direction detecting means 101, and roads stored in storage means 102. The first to calculate the position of the vehicle based on the map data
It is applied to a vehicle-mounted navigation device including the calculation means 103 and the second calculation means 104 that receives GPS signals from a plurality of satellites to calculate the position of the vehicle. GP from two satellites
By calculating the altitude of the vehicle based on the S signal and the position of the vehicle calculated by the first calculation means 103,
To achieve the above objectives.

[0013]

The first calculating means 103 calculates the position of the vehicle by so-called self-contained navigation. That is, the traveling locus of the vehicle is calculated based on the traveling direction and the traveling distance of the vehicle, and the calculated traveling locus and the road map data are collated to perform map matching to calculate the position of the vehicle. The second calculating means 104 calculates the altitude of the vehicle according to the simultaneous equations described above based on the GPS signals from at least two satellites and the position of the vehicle calculated by the self-contained navigation.

[0014]

EXAMPLE FIG. 2 shows the configuration of an example. The GPS receiver 1 receives the GPS signal through the antenna 2 and the above-mentioned G
PS position calculation is performed to detect the position of the vehicle. The vehicle speed sensor 3 is attached to, for example, a transmission,
Speedometer Generates a predetermined number of pulse signals per pinion rotation. The traveling distance of the vehicle can be detected by counting the number of pulses. The angular velocity sensor 4 detects the turning angle of the vehicle with a gyro, and the geomagnetic sensor 5 detects the absolute azimuth from the direction of the geomagnetism. The traveling direction of the vehicle is detected based on the detection signals from these sensors 4 and 5. The CD-ROM 6 is a storage device that stores road map data, and the driver 7 is a data reading device thereof.

The processing unit 8 is composed of a microcomputer and its peripheral parts, and the traveling distance detected based on the pulse signal from the vehicle speed sensor 3, the traveling direction detected by the angular velocity sensor 4 and the geomagnetic sensor 5, The position of the vehicle is calculated by self-contained navigation based on the road map data around the vehicle read from the CD-ROM 6, and the position calculated by this self-contained navigation and G
The position (Xu, Yu) of the vehicle is specified based on the position calculated by the PS receiver 1. Then, the position (Xu, Yu) of this vehicle is fed back to the GPS receiver 1, and the GPS receiver 1 is made to calculate the altitude Zu of the vehicle by the simultaneous equations described above. The image processing unit 9 is a CD-ROM
The road map data around the vehicle and the position data of the vehicle read out from 6 are imaged and displayed on the display unit 10.

3 to 5 are flowcharts showing an advanced arithmetic processing program executed by the microcomputer of the processing unit 8. The operation of the embodiment will be described with reference to this flowchart. The microcomputer executes this processing program every predetermined time. Step S
In 1, the geomagnetic sensor 5 detects the absolute azimuth,
In subsequent step S2, the angular velocity sensor 4 detects the turning angle of the vehicle. In step S3, the traveling azimuth of the vehicle is estimated based on the absolute azimuth detected by the geomagnetic sensor 5 and the turning angle detected by the angular velocity sensor 4. Further, the traveling distance of the vehicle is detected based on the pulse signal detected by the vehicle speed sensor 3 in step S4. In step S5, the traveling locus of the vehicle is calculated based on the traveling direction and traveling distance of the vehicle detected in the above step.

In step S6, the road map data around the vehicle is read from the CD-ROM 6, and in the following step S7 the traveling locus of the vehicle previously calculated is compared with the road shape of the road map data. If there is a matching road, The current position (Xu, Yu) of the vehicle is set on the road. That is, map matching is performed and the vehicle position (X
u, Yu) is calculated. In step S8, the road on which the vehicle is traveling is narrowed down to one by map matching, and it is determined whether or not the position of the vehicle can be specified on the road. If the position of the vehicle can be specified, the process proceeds to step S11 of FIG. When the vehicle is currently running and the road cannot be narrowed down to one and the position of the vehicle cannot be specified, the process proceeds to step S21 in FIG.

In step S11 of FIG. 4, the position data (Xu, Yu) of the vehicle calculated by self-contained navigation is output to the GPS receiver 1, and in step S12, the GPS
In the receiver 1, position data (Xu, Yu) and at least 2
The altitude Zu of the vehicle is calculated by the simultaneous equations described above based on the GPS signal radio waves received from the satellites. That is, (Xi, Yi, Zi) (i = 1, 2) and (X
u, Yu) is known data,

(2) (X1-Xu) ² + (Y1-Yu) ² + (Z1-Zu) ² = (R1-c × Δtu) ² (2)

## EQU3 ## ^{(X2-Xu) 2 + (} Y2-Yu) 2 + (Z2-Zu) 2 = (R2-c × Δtu) 2 ··· (3) (2), Zu unknowns from (3) And Δtu can be obtained. The altitude Zu of the vehicle calculated from the GPS receiver 1 is input and stored in step S13.

On the other hand, when the position of the vehicle cannot be specified by the self-contained navigation, the GPS positioning data is input from the GPS receiver 1 in step S21 of FIG. 5, and the following step S22.
It is determined whether or not the GPS positioning accuracy is good.

Here, the accuracy of the GPS positioning data (hereinafter,
This is referred to as GPS positioning accuracy). The GPS positioning accuracy is almost determined by the accuracy of the GPS signal itself and the positional relationship between the vehicle and each satellite. The accuracy of the former GPS signal itself is indicated by the accuracy data included in the GPS signal. Regarding the positional relationship between the latter vehicle and each satellite, the accuracy becomes worse as the satellites are closer to each other and the elevation angle of each satellite is smaller. Therefore, the GPS positioning accuracy is represented by the radius (unit: meter) of the error circle centered on the calculated coordinates, and the accuracy data included in the GPS signal and the positional relationship between the vehicle and each satellite are set as the radius of the error circle. A conversion table (not shown) for conversion is set and stored in the memory in advance.
Then, every time the GPS positioning calculation is performed, the conversion table is searched to find the radius of the error circle indicating the GPS positioning accuracy.

In step S22, it is determined whether or not the radius of the error circle indicating the GPS positioning accuracy is less than or equal to a predetermined value (for example, 200 m). If it is less than the predetermined value, it is determined that the GPS positioning accuracy is good, and the process proceeds to step S23. If it is larger than the predetermined value, the accuracy is considered to be poor and the process proceeds to step S24. If the GPS positioning accuracy is poor, the GPS receiver 1 this time is selected in step S24.
The GPS positioning data detected in step 9 is invalidated and the process ends. That is, when the position of the vehicle is not specified by self-contained navigation and the accuracy of the position of the vehicle calculated by GPS positioning is poor, the altitude calculation process is stopped.

When the GPS positioning accuracy is good, step S23
Go to the vehicle position calculated by self-contained navigation and GP
It is determined whether or not the position of the vehicle calculated by S positioning is more than the radius of the error circle of GPS positioning accuracy. If the distance between them is within the radius of the error circle of GPS positioning accuracy, the position of the vehicle calculated by self-contained navigation can be trusted to some extent, but the position of the vehicle is specified on one road by map matching. Since it could not be done, the altitude calculation processing is stopped. On the other hand, the vehicle position and GPS by self-contained navigation
If the vehicle position determined by the positioning is more than the radius of the error circle, the process proceeds to step S25, and the GPS positioning data is collated with the road map data around the vehicle. As a result of the collation in step S26, it is determined whether or not the GPS positioning coordinates can be specified on one road. If the GPS positioning coordinates can be specified, the process proceeds to step S11 of FIG. 4 to calculate the altitude Zu of the vehicle by the procedure described above. If the GPS positioning data cannot be specified on one road, the accuracy of the vehicle position based on the self-contained navigation and the vehicle position based on the GPS positioning are both poor, so the altitude calculation process is stopped.

As described above, the microcomputer of the processing section 8 executes the altitude calculation processing program every predetermined time, calculates the altitude Zu of the vehicle and stores it in the memory. Usually, in GPS positioning, when only three satellites can be captured, three-dimensional positioning cannot be performed, and thus the vehicle position with low accuracy is calculated by two-dimensional positioning. In such a case, four simultaneous equations are solved using the vehicle altitude Zu calculated and stored last time to calculate the vehicle position.
Since the positioning cycle in the GPS receiver is about 1 second, it can be considered that the altitude of the vehicle does not change significantly in 1 second even when the vehicle is traveling at high speed, so the previous altitude of the vehicle is used. If so, the position of the vehicle can be calculated with sufficiently high accuracy.

In this way, the vehicle position is calculated by the self-contained navigation by performing the map matching based on the traveling direction, the traveled distance and the road map data of the vehicle, and calculated by the GPS signals from at least two satellites and the self-contained navigation. Since the altitude of the vehicle is calculated based on the calculated vehicle position, even if four satellites cannot be captured, the altitude of the vehicle at the vehicle position can be calculated without increasing the amount of road map data. Further, even when only three satellites can be captured in GPS positioning, if the GPS positioning calculation is performed using the altitude of the vehicle previously calculated by the method described above, the position of the vehicle with sufficiently high accuracy is calculated by three-dimensional positioning. can do.

In the structure of the above embodiment, the vehicle speed sensor 3 serves as the distance detecting means, the angular velocity sensor 4 and the geomagnetic sensor 5 serve as the azimuth detecting means, the CD-ROM 6 serves as the storing means, and the processing section 8 serves as the first computing means. The GPS receiver 1 constitutes the second calculating means.

[0026]

As described above, according to the present invention, the position of the vehicle is calculated on the basis of the mileage, the heading and the road map data of the vehicle, and the calculated position of the vehicle and at least two satellites are calculated. Since the altitude of the vehicle is calculated on the basis of the GPS signal of, the altitude of the vehicle can be calculated without increasing the amount of road map data even when four satellites cannot be captured. Further, even when only three satellites can be captured in GPS positioning, if the GPS positioning calculation is performed using the altitude of the vehicle previously calculated by the method described above, the position of the vehicle with sufficiently high accuracy is calculated by three-dimensional positioning. can do.

[Brief description of drawings]

FIG. 1 is a complaint correspondence diagram.

FIG. 2 is a block diagram showing the configuration of an embodiment.

FIG. 3 is a flowchart showing an altitude calculation processing program.

FIG. 4 is a flowchart showing an altitude calculation processing program.

FIG. 5 is a flowchart showing an altitude calculation processing program.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 GPS receiver 2 Antenna 3 Vehicle speed sensor 4 Angular velocity sensor 5 Geomagnetic sensor 6 CD-ROM 7 Driver 8 Processing part 9 Image processing part 10 Display part 100 Distance detection means 101 Direction detection means 102 Storage means 103 First calculation means 104 No. 2 calculation means

Claims (1)

[Claims] 1. A distance detecting means for detecting a traveling distance of a vehicle, an azimuth detecting means for detecting a traveling azimuth of the vehicle, a storage means for storing road map data, and a traveling distance detected by the distance detecting means. A first calculation means for calculating the position of the vehicle based on the traveling direction detected by the direction detection means and the road map data stored in the storage means; and GPS signals from a plurality of satellites. A vehicle-mounted navigation device comprising: a second arithmetic means for receiving a vehicle position and calculating a position of the vehicle;
An in-vehicle navigation device, wherein the vehicle altitude is calculated based on the PS signal and the position of the vehicle calculated by the first calculating means.