JP2921413B2 - Vehicle navigation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation system for a vehicle that determines the direction of a vehicle using a direction sensor, and more particularly to a navigation device that determines the direction of a vehicle by effectively using GPS positioning data.

[0002]

2. Description of the Related Art A navigation device detects an accurate current position of a vehicle, and provides guidance to a destination based on the detected current position. In this way, in order to accurately guide the current position of the vehicle to provide guidance to the destination,
In addition to increasing the position detection accuracy by combining various sensors, the accuracy is further improved by using a position correction method such as map matching. For example, Japanese Unexamined Patent Publication No. 6-66577 discloses a geomagnetic sensor for detecting geomagnetism, a left and right wheel sensor for detecting a difference between left and right wheel rotational speeds of a front wheel of a vehicle for correcting an error of the geomagnetic sensor when a magnetic field is disturbed. ,
Furthermore, in addition to azimuth detection by a steering sensor for compensating when the left and right wheel sensors become inoperable at a low speed of less than 3.5 km / h, a GPS positioning system that receives a radio wave from an artificial satellite to perform position detection. When the road closest to the current position of the vehicle is selected by map matching, the road direction stored in the map information is compared with the estimated direction. There is disclosed a vehicle navigation device that determines a vehicle direction that conforms to the following. In this navigation device, the direction is calculated by receiving radio waves from GPS satellites. However, when the vehicle is traveling at low speed or turning right or left, the direction is determined by the Doppler effect. Since sufficient accuracy cannot be expected, no GPS azimuth is adopted.

[0003]

However, in such a conventional navigation device, when the vehicle is traveling at a low speed or turning right or left, the vehicle speed is reduced from the viewpoint that the azimuth accuracy is reduced. Since the GPS azimuth is adopted only when the value is equal to or greater than the predetermined value, the frequency of performing the azimuth correction using the GPS azimuth decreases,
There is a problem that the azimuth accuracy is reduced. Even if the vehicle speed is equal to or higher than a predetermined value, the GPS azimuth accuracy may deteriorate when the GPS arrangement or radio wave reception is poor. However, there is a problem that the azimuth is corrected to the wrong azimuth, and the azimuth accuracy is reduced.

Accordingly, the present invention solves the above-mentioned problems, and further improves the azimuth accuracy of a vehicle by using an estimated azimuth error calculated based on the arrangement of GPS satellites based on the current position and the moving speed of the vehicle. It is an object to provide a navigation device for a vehicle.

[0005]

In order to achieve the above object, a vehicle navigation apparatus according to the present invention has a receiving means for receiving a signal from a satellite, and a signal from the receiving means. Traveling direction calculating means for calculating the traveling direction of the vehicle based on the position information; satellite position detecting means for detecting the location of the satellite based on a signal from the receiving means; moving speed detecting means for detecting the moving speed of the vehicle; Azimuth error estimating means for estimating an error in the heading obtained by the heading calculating means based on the moving speed obtained by the speed detecting means and the satellite arrangement obtained by the satellite position detecting means, and the heading error estimating means Determining means for determining whether or not the estimated azimuth error estimated by the above is equal to or less than a predetermined value.

According to a second aspect of the present invention, there is provided a vehicular navigation apparatus comprising: receiving means for receiving a signal from a satellite; and heading calculating means for calculating a heading of a vehicle based on a signal from the receiving means. Satellite position detecting means for detecting the arrangement of the satellite based on a signal from the receiving means; moving speed detecting means for detecting the moving speed of the vehicle; moving speed and satellite position detecting means obtained by the moving speed detecting means Azimuth error estimating means for estimating an error in the heading obtained by the heading calculating means based on the obtained satellite arrangement;
Vehicle heading estimating means for estimating the heading of the vehicle; estimated heading estimated by the vehicle heading estimating means based on the heading calculated by the heading calculating means and the estimated heading error estimated by the heading error estimating means Correction amount calculation means for calculating a correction amount for correcting the vehicle direction, and traveling direction correction means for correcting the estimated direction estimated by the vehicle traveling direction estimation means based on the correction amount calculated by the correction amount calculation means. .

[0007]

According to a third aspect of the present invention, there is provided a navigation apparatus for a vehicle, comprising: receiving means for receiving a signal from a satellite; and a heading of the vehicle based on the signal from the receiving means. Traveling direction calculating means for calculating the position of the satellite based on a signal from the receiving means, moving speed detecting means for detecting the moving speed of the vehicle, and the moving speed detecting means An azimuth error estimating means for estimating an error of the heading obtained by the heading calculating means based on the obtained moving speed and the arrangement of satellites obtained by the satellite position detecting means; Determining means for determining whether the estimated azimuth error is equal to or less than a predetermined value; vehicle heading estimating means for estimating the heading of the vehicle; Error is estimated by the vehicle traveling direction estimating means based on the estimated heading error estimated by the traveling azimuth and the azimuth error estimation means calculated by said traveling azimuth calculation means when it is determined to be equal to or less than a predetermined value Correction amount calculating means for calculating a correction amount for correcting the estimated azimuth, and operation azimuth correction for correcting the estimated azimuth estimated by the vehicle traveling azimuth estimating means based on the correction amount calculated by the correction amount calculating means. Means.

[0008]

The vehicle navigation device of the present invention estimates the azimuth error at the time of reception with respect to the GPS azimuth calculated based on the signal from the receiving means, so that the accuracy of the GPS azimuth obtained at that time can be estimated. Can be confirmed. Therefore, it is determined whether or not to use the calculated GPS azimuth based on the estimated azimuth error, and when the estimated azimuth error is equal to or less than a predetermined value, the GPS azimuth calculated from the signal received at that time is determined. Since it is adopted, it is possible to always use a direction with high accuracy. Further, by calculating a correction amount according to the estimated azimuth error and correcting the estimated azimuth from the azimuth estimating means for estimating the azimuth of the vehicle, a highly accurate azimuth of the vehicle can be provided. .

Furthermore, by adopting only a highly accurate GPS azimuth having a small estimated azimuth error and correcting the estimated azimuth based on the estimated azimuth error, a more accurate vehicle traveling azimuth can be calculated.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows a vehicle navigation device according to the present invention.
As shown in the figure, an input / output device 1 for inputting and outputting information relating to route guidance, a current position detection device 2 for detecting information relating to the current position of the vehicle, navigation data required for calculating a route, and guidance required for route guidance The information storage device 3 in which data and the like are recorded, performs route search processing and display / voice guidance processing necessary for route guidance, and
It comprises a central processing unit 4 for controlling the entire system.

The input / output device 1 allows input of information necessary for setting a destination such as a departure point, a destination, a passing point, and the like, and enables a driver to output guidance information by voice and / or screen when required. It has a function of instructing the central processing unit 4 to perform a navigation process according to the driver's will and printing out the processed data, data of data communication, and the like. As a means for realizing the function, the input unit inputs a point by a telephone number or coordinates, requests a route guidance, sets a mode, such as setting a destination or a passing point. The output unit includes a touch switch 11 for performing switching, a switch including a key switch, and the like.
A display 12 for automatically displaying route guidance on a screen in response to a driver's request, a printer 13 for printing out data processed by the central processing unit 4 and data stored in the information storage device 3, and outputting voice guidance for route guidance. Speaker 16 and the like.

The display 12 is composed of a color CRT or a color liquid crystal display, and is necessary for navigation such as a route setting screen, a section map screen, and an intersection map screen based on map data and guidance data processed by the central processing unit 4. In addition to outputting all screens in color display, buttons for setting route guidance, guiding during route guidance, and switching screens are displayed on this screen. Especially,
The passing intersection information such as the passing intersection name is displayed in color in a pop-up on the section map screen at any time.

The display 12 is provided in an instrument panel near the driver's seat. The driver can confirm the current position of the vehicle by looking at the section map and obtain information on a route from now on. it can. Further, the display 12 is provided with a touch switch 11 corresponding to the display of the function button, and the above operation is executed based on a signal input by touching the button. Key switch is provided, and mode switching such as guidance and destination setting is performed by pressing a key. The input signal generating means including the key switch and the touch switch 11 constitutes an input section.

The current position detecting device 2 includes a GPS receiving device 21 using a satellite navigation system (GPS) and a beacon receiving device 22, for example, a data transmitting / receiving device 23 receiving a GPS correction signal using a car phone or an FM multiplex signal. ,
Absolute azimuth sensor 2 composed of, for example, a geomagnetic sensor
4, a relative direction sensor 25 including, for example, a wheel sensor, a steering sensor, and a gyro, a distance sensor 26 for detecting a traveling distance from the number of rotations of the wheel, and the like. The absolute direction sensor 24 and the relative direction sensor 25
Function as the direction estimating means described in the claims.

The information storage device 3 includes map data, intersection data, node data, road data including road direction data, photograph data, destination data, guide point data, detailed destination data, and road name data necessary for route guidance. , Is a database in which all data such as branch point data, address data, display guidance data, and voice guidance data are recorded, and is constituted by an optically readable recording medium such as a CD-ROM.

The central processing unit 4 executes C
PU 40, a program for performing processing such as route search, a display output control required for route guidance, a program for performing voice output control necessary for voice guidance, and a first ROM 41 storing data required for the program, RA that temporarily stores route guidance information and data being processed
M42, a second ROM 43 storing display information data necessary for route guidance and map display, and an image memory 4 storing image data used for screen display on a display.
4. An image processor 45 that extracts image data from the image memory 44 based on a display output control signal from the CPU 40, performs image processing, and outputs the processed image to a display.
Information storage device 3 based on the audio output control signal from
A voice processor 46 for synthesizing voice data (phrases, a single sentence, sound, etc.) read out of the speaker, converting it into an analog signal and outputting it to the speaker 16, a communication interface 47 for exchanging input / output data by communication, and A sensor input interface 48 for taking in a sensor signal of the current position detecting device 2 and a clock 49 for writing date and time in the internal diagnostic information are provided.
Here, the route guidance is configured so that the driver can select either the screen display or the voice output.

The data communication device 5 accumulates a large amount of route guidance information, transmits / receives data to / from an external information center such as VICS communication, ATIS communication provided by a user's request, etc. Information storage media such as cards (digital data storage means)
And a data transmission / reception unit 51 for transmitting and receiving data for inputting point coordinates using this information, and a telephone call and a destination for specifying a point and acquiring its surrounding information. Phone caller 5 that automatically makes a phone call to make a phone call with the destination after setting
2 and so on.

FIG. 4 shows a flow of processing of the entire vehicle navigation system according to the present invention. First, a current position (departure place) required for a route search is obtained (step S1). Next, a destination setting condition is entered on the destination setting screen to set the destination (step S2),
A route search is performed (step S3). When the guidance start key is pressed on the searched route to start the route guidance, the position and the direction of the own vehicle are measured, and the current position is tracked (step S4). Next, route guidance is performed by voice and / or display based on the set route (step S5). Furthermore, calculate the distance from the current position to the destination,
The arrival at the destination is determined based on whether or not the distance has become equal to or less than the predetermined distance (step S6). If the distance has become equal to or less than the predetermined distance, it is determined that the vehicle has arrived at the destination, and the route guidance ends. On the other hand, if the distance from the current position to the destination is not less than the predetermined distance, the process returns to step S4 to continue the current position tracking. This current position tracking is performed by the current position detecting device, and based on the position and direction signals of the vehicle calculated by the GPS receiving device shown in FIG. 5, the output signals of various sensors, and the road direction of the map information, the current position of the vehicle. Is calculated.

The GPS receiver used in the vehicle navigation system according to the present invention shown in FIG.
0 to receive the radio waves from multiple satellites,
The vehicle speed, the bearing, and the estimated bearing error are calculated, and the information is transmitted via the communication unit. Data receiving unit 2
12, when the radio waves of each satellite are received by the antenna 210,
The data is extracted by detecting the received signal and analyzing the navigation message. The satellite distance calculation unit 213
The distance to the satellite is calculated from the transmission time when the radio wave was transmitted from the satellite, the reception time by the clock 211 when the radio wave was received, and the position coordinates of the satellite when the radio wave was transmitted. The current position and altitude of the vehicle are calculated based on the information. Doppler calculator 2
The vehicle speed calculation unit 216 calculates the vehicle speed using the Doppler value calculated in 14, and the azimuth calculation unit 218 calculates the traveling azimuth of the vehicle. Further, in the present invention, the satellite position information calculation unit 215 calculates the arrangement of each satellite with respect to the vehicle, and the estimated azimuth error calculation unit 219 calculates the satellite arrangement calculated by the satellite position information calculation unit 215 and the vehicle speed calculation unit 21.
The estimated azimuth error is calculated based on the vehicle speed calculated in step S6. Here, the satellite position information calculating unit 215 is a satellite position detecting unit described in the claims, the vehicle speed calculating unit 216 is a moving speed detecting unit, the azimuth calculating unit 218 is a traveling azimuth calculating unit, and the estimated azimuth error calculating unit 219 is a azimuth error estimating unit. Function as each.

In the GPS azimuth where the azimuth is calculated based on the data received from the satellite, an error occurs in the azimuth according to the arrangement of the satellite and the vehicle speed. For example, when the direction of the satellite, the arrangement of the satellites, and the like with respect to the vehicle change, the error in the direction increases or decreases. Also, the azimuth error changes depending on the vehicle speed at the time of reception even if the positions (arrangements) of the satellites are the same. Therefore, the estimated azimuth error calculator 2
In 19, such an error of the azimuth is estimated, and as a calculation method thereof, for example, it is obtained based on experimental data [Equation 1]

[0021]

## EQU1 ## The estimated azimuth error is calculated using Estimated azimuth error = A × HDOP / V. The error is output in degrees. Here, A: constant (for example, 100), HD
OP represents the rate of decrease in the accuracy of the two-dimensional position in the horizontal direction, and V represents the vehicle speed. In the present embodiment, the estimated azimuth error is calculated using a function based on the experimental data. However, as a method of calculating the estimated azimuth error, the estimated azimuth error is calculated using a table created based on the experimental data. You may.

Next, the processing for determining the GPS azimuth adoption will be described with reference to the flowchart shown in FIG. First, it is determined whether a signal from a satellite has been received (step S1).
1) If reception is possible, it is determined whether or not the estimated azimuth error of the GPS azimuth calculated by the estimated azimuth error calculator 219 is equal to or smaller than a predetermined value according to the reception state (step S1).
2) If the estimated azimuth error is equal to or smaller than a predetermined value, it is determined whether the vehicle is traveling straight (step S13),
When the vehicle is traveling straight, it is determined whether the GPS azimuth is stable. Here, for example, as a result of comparing the currently calculated GPS azimuth with the previously determined azimuth,
It is determined whether the difference is equal to or less than a predetermined value (step S14). If all of these conditions are satisfied, the azimuth correction amount is determined based on the estimated azimuth error (step S15), and the guess calculated by the absolute azimuth sensor 24 and / or the relative azimuth sensor 25 as the azimuth estimating means is obtained. The azimuth is corrected (step S16). Therefore, even if the estimated azimuth error is equal to or more than a predetermined value even when the vehicle speed is high, the vehicle is turning right or left, or the azimuth detected this time has changed by a predetermined value or more compared to the azimuth determined last time. GPS
The direction is not adopted.

In this system, the current traveling direction is estimated based on the direction detected by the absolute direction sensor and / or the relative direction sensor, and the estimated direction is estimated by GP.
The correction is made in the S direction. Therefore, in the process of determining whether or not to use the GPS azimuth shown in FIG. 6, if the GPS azimuth is not adopted, the guess azimuth is used as the traveling azimuth without correcting the guess azimuth. .

Here, the judgment processing in step S12 functions as the judgment means described in the claims, and step S15
The process in (1) functions as the correction amount calculating means described in the claims, and the processing in step S16 functions as the estimated azimuth correcting means described in the claims.

By performing the process of determining whether to use the GPS azimuth as described above, only the GPS azimuth with high accuracy can be employed, so that the traveling azimuth of the vehicle can be detected more accurately. Become. Further, since the correction amount is determined based on the calculated estimated azimuth error and the azimuth obtained from the various azimuth sensors is corrected, a more accurate azimuth can be obtained.

The correction amount can be calculated by, for example, the following [Equation 2].

[0027]

## EQU2 ## Correction amount = (GPS azimuth− estimated azimuth ) × correction coefficient Here, GPS azimuth: traveling azimuth calculated from GPS signal, estimated azimuth: traveling azimuth of vehicle detected from various azimuth sensors, correction coefficient: It is a coefficient for determining how much to correct.

FIG. 7 is a table showing the relationship between the calculated estimated azimuth error and the correction coefficient. Thus, for example, when the estimated azimuth error is 10 °, it is known that the correction coefficient is ４, and the correction amount is calculated from [Equation 2] using this correction coefficient. Further, the estimated azimuth detected from the various azimuth sensors is corrected by using this correction amount in the following equation (Equation 3).

[0029]

## EQU00003 ## Corrected direction = estimated direction + correction amount

Therefore, while using only the GPS azimuth in a good reception state, an error is estimated for the azimuth that has been adopted, and further obtained from various azimuth sensors that detect the azimuth of the vehicle according to the error. By correcting the estimated direction, a more accurate direction can be obtained.

The configuration of the main part of the present invention will be described with reference to FIG. 1. A signal from a GPS satellite is received by a GPS receiver 21, and a satellite position information calculator 215, which is a satellite position detector, detects the position of the received satellite. , The vehicle speed (speed) is calculated by a vehicle speed calculation unit 218 as a moving speed detection unit, and the satellite arrangement at that time is determined based on an experiment by an estimated azimuth error calculation unit 219 as an azimuth error estimation unit. An estimated azimuth error is calculated from a function obtained from the relationship between the (satellite arrangement information) and the vehicle speed (speed) or a table of the arrangement of the receiving satellites (satellite arrangement information) and the vehicle speed (speed). Based on the error, it is determined whether to use the azimuth calculated by the azimuth calculation unit as the traveling azimuth calculation means.

The correction means calculates a correction coefficient and a correction amount based on the azimuth error calculated by the azimuth error estimating means, and the estimated azimuth correcting means calculates the correction coefficient and the correction amount based on the correction amount calculated from the correcting means. The estimated direction detected from a certain absolute direction sensor 24 and / or a relative direction sensor 25 is corrected.

In FIG. 1, the GPS receiver 21 is provided with an azimuth error estimating means, and the obtained estimated azimuth error signal is transmitted to the central processing unit. However, in FIG. (Vehicle speed, arrangement of receiving satellites, etc.) are transmitted to the central processing unit, and the estimated azimuth error is calculated in the central processing unit. Further, in FIG. 1, the speed is calculated by the speed calculation unit 218 in the GPS receiver 21 as the moving speed detecting means, but in FIG. 2, the vehicle speed is detected by the moving speed detecting means such as a vehicle speed sensor provided on the vehicle side. ing.

According to the present invention, since the traveling direction is determined based on the GPS direction and the estimated direction error obtained by estimating the direction error with respect to the GPS direction in addition to the conventional direction sensor, accurate direction calculation can be performed. Further, by comparing with the road direction in the map information, more accurate map matching can be performed. Therefore, the reliability of the navigation device can be improved.

Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, as shown in FIG. 7, the correction coefficient for the estimated azimuth error is set in a table, but the correction coefficient may be set to 1 uniformly. That is, the azimuth calculating unit 21 which is the traveling azimuth calculating means
A value obtained by subtracting the estimated azimuth detected from the absolute azimuth sensor 24 and / or the relative azimuth sensor 25 as the azimuth estimating means from the GPS azimuth calculated in step 8 may be used as the correction amount.

Further, in the present embodiment, it is determined whether or not to use the GPS azimuth. However, even if the estimated azimuth error is large without using such determination means,
The estimated direction may be corrected by calculating a correction amount based on the estimated direction error.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a main part of the present invention corresponding to claim 1;

FIG. 2 is a diagram showing a configuration of a main part of the present invention corresponding to claim 2;

FIG. 3 is a diagram showing the configuration of the entire vehicle navigation system according to the present invention.

FIG. 4 is a diagram showing a flow of processing of the entire vehicle navigation system according to the present invention.

FIG. 5 is a diagram showing a configuration example of a GPS receiving device used for a vehicle navigation device according to the present invention.

FIG. 6 is a diagram showing a flow of a process of determining GPS direction adoption in the vehicle navigation device according to the present invention.

FIG. 7 is a table showing a relationship between a calculated estimated azimuth error and a correction coefficient.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 input / output device, 2 current position detecting device, 3 information storage device, 4 central processing device, 11 touch switch, 12
... Display, 13 ... Printer, 16 ... Speaker, 2
1 ... GPS receiver, 22 ... beacon receiver, 23 ...
Data transmitting / receiving device, 40 CPU, 41 first ROM,
42 RAM, 43 second ROM, 44 image memory,
45 image processor, 46 audio processor, 47
Communication interface, 48: Sensor input interface, 49: Clock

Claims (3)

(57) [Claims] A receiving means for receiving a signal from a satellite; a heading calculating means for calculating a heading of a vehicle based on the signal from the receiving means; Satellite position detecting means for detecting an arrangement; moving speed detecting means for detecting a moving speed of the vehicle; a moving speed obtained by the moving speed detecting means and a satellite arrangement obtained by the satellite position detecting means. Azimuth error estimating means for estimating the error of the traveling azimuth obtained from the traveling azimuth calculating means, and determining means for determining whether or not the estimated azimuth error estimated by the azimuth error estimating means is equal to or less than a predetermined value. A navigation device that employs the traveling direction calculated by the traveling direction calculation means when the estimated direction error is equal to or less than a predetermined value. 2. A receiving means for receiving a signal from a satellite, a heading calculating means for calculating a heading of the vehicle based on a signal from the receiving means, and a heading calculating means for calculating a heading of the vehicle based on a signal from the receiving means. Satellite position detecting means for detecting an arrangement; moving speed detecting means for detecting a moving speed of the vehicle; a moving speed obtained by the moving speed detecting means and a satellite arrangement obtained by the satellite position detecting means. A heading error estimating means for estimating an error of the heading obtained by the heading calculating means, a vehicle heading estimating means for estimating the heading of the vehicle, and a heading calculated by the heading calculating means. A correction amount calculation for calculating a correction amount for correcting the estimated azimuth estimated by the vehicle traveling azimuth estimating unit based on the estimated azimuth error estimated by the azimuth error estimating unit. And a traveling azimuth correcting means for correcting an estimated azimuth estimated by the vehicle traveling azimuth estimating means based on the correction amount calculated by the correction amount calculating means. 3. Receiving means for receiving a signal from a satellite, traveling direction calculating means for calculating a traveling direction of a vehicle based on a signal from the receiving means, Satellite position detecting means for detecting an arrangement; moving speed detecting means for detecting a moving speed of the vehicle; a moving speed obtained by the moving speed detecting means and a satellite arrangement obtained by the satellite position detecting means. Azimuth error estimating means for estimating the error of the traveling azimuth obtained from the traveling azimuth calculating means, and determining means for determining whether or not the estimated azimuth error estimated by the azimuth error estimating means is equal to or less than a predetermined value. A vehicle traveling direction estimating means for estimating the traveling direction of the vehicle; and calculating the traveling direction calculating means when the estimating direction error is determined to be equal to or less than a predetermined value. A correction amount calculating means for calculating a correction amount for correcting the estimated heading that is estimated by the vehicle traveling direction estimating means based on the estimated heading error estimated by been headed direction and the azimuth error estimation means, the correction A navigation device for a vehicle, comprising: a traveling direction correcting unit that corrects an estimated direction estimated by the vehicle traveling direction estimating unit based on a correction amount calculated by the amount calculating unit.