JPH0618274A - Car navigation system - Google Patents

Abstract

PURPOSE:To detect a highly accurate present position by operating a coefficient of a detecting accuracy index which determines how correct the range of the recognizing error is, while taking the reliability by a self-navigating means into consideration. CONSTITUTION:As a vehicle runs, a direction sensor 2 and a running distance sensor 3 are activated. A central processing device 4 calculates the present position of the vehicle based on the data provided from the sensors 2, 3. At the same time, the central processing device 4 operates the present position of the vehicle based on the waves received by a GPS receiver 12 from a satellite. When the GPS receiver 12 receives a detecting accuracy index (HDOP) from the satellite, it obtains the difference (ERD) of the present position based on the data from the satellite and that from the sensors 2, 3. A reliability coefficient MMK is obtained from the effective distance of the present position detected by the sensors 2, 3, and a function (k) is calculated according to a formula MMMXERD/HDOP. In order to detect whether the map matching is proper, the difference (ERD) is compared with a value obtained by multiplying the HDOP by the function (k). If the difference (ERD) is larger, the map matching is determined as an error, and the present position is corrected and moved to a position obtained by the GPS navigation method.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a self-contained navigation means and GPS.
The present invention relates to a vehicle-mounted navigation device that also uses navigation means to detect the current position of a vehicle from both data.

[0002]

2. Description of the Related Art Conventionally, as an on-vehicle navigation device, a self-contained navigation means by map matching for measuring a current position by using detection data from a distance sensor or a direction sensor and matching it on a map, and a radio wave from a satellite are used. There is one that detects the current position of the vehicle in combination with GPS navigation means for measuring the current position. This is the self-contained navigation means to match the current position measured by the data from the sensor on the map,
When this matching current position is within the recognition error range centered on the current position measured by the GPS navigation means, the matching current position is adopted, while the self-contained navigation means malfunctions and the matching current position is constant outside the recognition error range. When the distance is longer than the distance, the current position measured by the GPS navigation means is adopted instead of using the current position for matching.

[0003]

[SUMMARY OF THE INVENTION Incidentally, if matching the current position by autonomous navigation means employs a matched current position by autonomous navigation means or rural is within the recognition error range of the GPS navigation unit, GPS navigation device was measured It is decided whether to adopt the current position. However, how accurate the recognition error range is is determined by the positioning accuracy index (HDOP: horizontal positioning accuracy decrease rate) that is determined by the satellite placement state (see FIG. 2), but the positioning accuracy index depends on the satellite positional relationship. In addition to the above, it may be intentionally changed by the satellite administrator (the coefficient k of the linear line of FIG. 2 changes).

The present invention was devised in view of the above situation, and an object of the present invention is to provide an on-vehicle navigation device capable of detecting a current position with high accuracy by monitoring a coefficient k of a changing positioning accuracy index. Is.

[0005]

In order to achieve the above object, the present invention uses self-contained navigation means for measuring the current position based on the detection data from the current position detecting means and matching it on a map, and radio waves from a satellite. If the matching current position of the GPS navigation means for measuring the current position and the self-contained navigation means is within the recognition error range centered on the measurement current position of the GPS navigation means, the matching current position is adopted, but outside the recognition error range. If there is a matching current position by self-contained navigation means in G
In a vehicle-mounted navigation device comprising correction means for matching and correcting the current position on a map within the error recognition range of the PS navigation means, the self-contained navigation means determines the coefficient of the positioning accuracy index that determines how accurate the recognition error range is. And a calculation means for calculating the reliability in consideration of

[0006]

According to the structure of the present invention , the self-contained navigation means measures the current position based on the detection data from the current position detection means and matches it on the map, and the GPS navigation means measures the current position by the radio wave from the satellite. Therefore, the correcting means adopts the matching current position when the matching current position by the self-contained navigation means is within the recognition error range centered on the current measurement position of the GPS navigation means, while the self-contained navigation means is outside the recognition error range. When there is a matching current position according to, the current position is matched and corrected on the map within the recognition error range of the GPS navigation means, but the calculation means determines the coefficient of the positioning accuracy index that determines how accurate the recognition error range is. By calculating in consideration of the reliability of the means, the current position can be detected in accordance with the change of the coefficient of the positioning accuracy index.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing a circuit configuration, and FIG. 2 is an HDOP when an electric wave from a satellite is received in an ideal state.
Is a graph showing the relationship between the error recognition range and FIG. 3, FIG. 3 is a flowchart showing the operation of calculating the positioning accuracy index, and FIG.

In the vehicle-mounted navigation device 1 shown in FIG. 1, the central processing unit 4 calculates the current position of the vehicle based on the data provided from the direction sensor 2 and the distance sensor 3, and the road displayed on the display device 5 is displayed. The current position is synthesized and displayed on the map. The map information provided to the display device 5 is C
It is stored in the external storage device 6 including a D-ROM or the like. The road map data stored in the external storage device 6 is subdivided by assigning a number to each node (node) such as an intersection or a corner of a road, and assigning a number to each road (link). The data stored in the external storage device 6 is read by the media controller 7 and temporarily stored in the buffer memory 8 via the central processing unit 4. The buffer memory 8 sequentially sends the necessary data to the image memory 9 via the central processing unit 4. The data stored in the image memory 9 is converted into an image by the display control device 10 and displayed on the display device 5. The data stored in the image memory 9 is updated as the vehicle travels. Reference numeral 11 is a keyboard for inputting and outputting various operations.

Position information is input to the central processing unit 4 from a satellite by the GPS receiver 12, and the central processing unit 4 measures the current position based on the position information. For the radio waves from the satellite, a positioning accuracy index (HDO) that determines the recognition error range centered on the current measurement position
P) is included, and the relationship between the positioning accuracy index (HDOP) and the recognition error range is a linear straight line as shown in FIG. The coefficient k between the positioning accuracy index (HDOP) and the recognition error range is intentionally changed in addition to being determined by the satellite arrangement state, but the function k is provided from the direction sensor 2 and the distance sensor 3. It is calculated in consideration of the reliability of the matching current position by the map matching measured based on the data. That is, first, the difference ERD between the current measured position by GPS navigation and the matched current position by map matching is calculated. Further, the reliability MMK of the matching current position by map matching is obtained, for example, by how many km the matching current position has matched with the road on the map in the past (effective distance). After multiplying the difference ERD by the reliability MMK, the coefficient k is obtained by dividing by the positioning accuracy index (HDOP).

Next, the operation of the embodiment of the present invention having the above structure will be described with reference to the flow charts shown in FIGS.

For the calculation of the coefficient k, the azimuth sensor 2 and the travel distance sensor 3 operate as the vehicle travels, and the central processing unit 4 calculates the current position of the vehicle based on the data provided from these sensors 2 and 3. At the same time, while the central processing unit 4 is calculating the current position of the vehicle based on the radio wave received from the satellite of the GPS receiver 12, first, the GP
When the S receiver 12 receives HDOP from the satellite, it calculates the difference (ERD) between the current position obtained from the satellite and the current position obtained from the sensors 2 and 3. Then, the reliability coefficient MMK is obtained from the effective distance of the current position obtained from the sensors 2 and 3.
After that, the coefficient k is calculated by the formula of MMM × ERD / HDOP.
To calculate.

Next, in determining whether map matching is possible, the difference (ERD) between the current position obtained from the satellite and the current position obtained from the sensors 2 and 3 is obtained. Then, it is determined whether or not this difference (ERD) is larger than a value obtained by multiplying HDOP by a function k. If the difference (ERD) is smaller, the process returns, that is, it is determined that the map matching is correct. Without moving the current position,
If the difference (ERD) is larger, the map matching is determined to be a malfunction and the current position is moved and corrected to the position obtained by GPS navigation.

[0013]

According to the present invention As apparent from the above description, when modifying means have a consistent current position by autonomous navigation means in the recognition error range around the measured current position of the GPS navigation means that While adopting the matching current position, when the matching current position by the self-contained navigation means is outside the recognition error range, the current position is adjusted and corrected on the map within the recognition error range of the GPS navigation means, but the calculation means is in the recognition error range. The current position can be detected by calculating the coefficient of the positioning accuracy index that determines the degree of accuracy in consideration of the reliability of the autonomous navigation means, so that the current position can be detected in response to the change in the coefficient of the positioning accuracy index. Can improve the accuracy of

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of a vehicle-mounted navigation device.

FIG. 2 is a graph showing the relationship between HDOP and error recognition range when radio waves from a satellite are received in an ideal state.

FIG. 3 is a flowchart showing an operation of calculating a positioning accuracy index.

FIG. 4 is a flowchart showing detection of a map matching malfunction.

[Explanation of symbols]

 1 Car Navigation System 2 Direction Denser 3 Distance Sensor 4 Central Processing Unit 5 Display Device 6 External Storage Device 7 Media Controller 8 Buffer Memory 9 Image Memory 10 Display Control Device 11 Keyboard 12 GPS Receiver

Claims (2)

[Claims] 1. A self-contained navigation means for measuring a current position based on detection data from the current position detecting means and matching it on a map, a GPS navigation means for measuring the current position by a radio wave from a satellite, and a measurement of the GPS navigation means. If there is a matching current position by the self-contained navigation means within the recognition error range centered on the current position, the matching current position is adopted, while if there is a matching current position by the self-contained navigation means outside the recognition error range, G
In a vehicle-mounted navigation device that includes a correction unit that corrects the measured current position of the PS navigation means on a map, the coefficient of a positioning accuracy index that determines how accurate the recognition error range is, An in-vehicle navigation device, characterized in that it is provided with a computing means that takes into consideration the computation. 2. The on-vehicle navigation device according to claim 1, wherein the reliability of the self-contained navigation means is calculated based on whether the matching current position matches a road on a fixed distance map.