JPH0327083A - On-vehicle navigation device - Google Patents

Abstract

PURPOSE:To detect the travel distance of a vehicle accurately at all by finding the mean value and standard deviation of temporary distance correction coefficients which are obtained every time the vehicle turns at an intersection, and using a mean value when the standard deviation becomes less than a specific value as a new distance correction coefficient. CONSTITUTION:When it is decided that the vehicle turns at an intersection, a CPU 7 finds the intersection distance lm between a current detected intersection and a last detected point by intersection leading-in operation and the lead-in distance DELTAl between the current position by current position recognition and the current detected intersection according to map data, and further finds the difference the distance lm and distance DELTAl as the actual travel distance lr of the vehicle and lm/lr as a temporary distance correction coefficient Ro. The CPU 7 finds the mean value and standard deviation of the coefficient Ro and regards the mean value when the standard deviation becomes less than the specific value as a new distance correction coefficient R. Consequently, the travel distance of the vehicle can be detected accurately at all times.

Description

[Detailed description of the invention] Technical field The present invention relates to an on-vehicle navigation device.

BACKGROUND ART In recent years, map data including road data obtained by digitizing each point on a road on a map is stored in a storage medium such as a CD-ROM, and the current location of a vehicle can be recognized and a certain range including the current location can be stored. An in-vehicle navigation device has been developed and put into practical use that reads a group of map data for the region from a storage medium and displays it on a display as a map of the area around the vehicle's current location, and also automatically displays the vehicle's own position indicating the vehicle's current location on the map. It is being done.

Such in-vehicle navigation devices are configured to use a distance sensor to determine the traveling distance of the vehicle, and a direction sensor to determine the traveling direction of the vehicle, and to estimate the current location of the vehicle on a map from the traveling distance and the traveling direction. By the way, in distance sensors and direction sensors, it is inevitable that errors will occur in the output data obtained due to their accuracy, so it is necessary to correct the output data using a correction coefficient.

Here, since the detection distance of the distance sensor changes depending on the type of tire, etc., adjustment is required for each vehicle.

Moreover, the geomagnetic sensor is installed so that the direction of travel of the vehicle matches the direction of the sensor, but errors occur during installation and adjustment is required for each vehicle.

Therefore, when installing this type of navigation device, both sensors must be corrected.

As a method of this correction, for example, Japanese Patent Application Laid-Open No. 62-14001
A method disclosed in Japanese Patent No. 8 is known, but with such a correction method, it is difficult to perform accurate correction at one time.

Furthermore, since the method requires manual labor, the operation becomes complicated, and a simpler method is required.

Further, the error in the traveling distance obtained by the distance sensor is not only due to sensor accuracy, but also due to tire wear, tire air pressure, slip, etc. Therefore, the distance correction coefficient once set. If you use it all the time, you won't always be able to accurately determine the distance traveled.

Furthermore, even when using a geomagnetic sensor that detects the vehicle's direction based on geomagnetism (earth's magnetic field), the north indicated by this geomagnetic sensor is not map north, so the direction correction coefficient is used to detect the direction of the geomagnetic sensor. Correction of the output data is performed. However, since this azimuth correction coefficient changes depending on the region, it is difficult to keep the azimuth correction coefficient constant.
This means that the running direction of the vehicle cannot always be detected accurately.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an in-vehicle navigation device that can always accurately detect the travel distance and travel direction of a vehicle by always setting the latest distance correction coefficient and azimuth correction coefficient.

In the in-vehicle navigation device according to the present invention, when it is detected that the vehicle has turned at an intersection, intersections near the current location are detected from road data by current location recognition, and when this detected intersection is corrected as the current location on the map, the road Based on the data, calculate the inter-intersection distance between the currently detected intersection and the previously detected intersection and the pull-in distance between the current location and the currently-detected intersection based on current location recognition, and calculate the difference between this inter-intersection distance and the pull-in distance by the vehicle's actual distance. A provisional distance correction coefficient is determined based on the distance between intersections and the actual distance traveled, and the average value and standard deviation of the provisional distance correction coefficients obtained each time the vehicle turns at an intersection is determined. The average value when becomes less than a predetermined value is used as a new distance correction coefficient.

In the in-vehicle navigation device according to the present invention, the road angle of the current location is determined from the road data through current location recognition, and the driving direction of the vehicle is determined based on the output data of the direction sensor, and the difference between this road angle and the driving direction is calculated as an angular deviation. The average value and standard deviation of the angle deviation obtained each time the vehicle turns at an intersection are determined, and the average value when the standard deviation becomes a predetermined value or less is used as a new angle correction coefficient. It becomes.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing an embodiment of an in-vehicle navigation device according to the present invention. In the figure, 1 is a direction sensor for detecting the running direction of the vehicle, 2 is an angular velocity sensor for detecting the angular velocity of the vehicle, 3 is a distance sensor for detecting the distance traveled by the vehicle, and 4 is latitude and longitude information. GPS (
Global Positioning System II
) device, and the detection output of each of these sensors (devices) is supplied to the system controller 5.

As the direction sensor 1, for example, a geomagnetic sensor is used that detects the running direction of the vehicle using geomagnetism (earth's magnetic field).

The system controller 5 receives the detection outputs of the sensors (devices) 1 to 4 as input and processes them such as A/D (analog/digital) conversion. A CPU (Central Processing Circuit) that calculates the vehicle's travel distance, travel direction, current location coordinates (longitude, latitude), etc. based on the output data of each sensor (device) 1 to 4.
7, a ROM (read-only memory) 8 in which various processing programs and other necessary information for the CPU 7 are written in advance, and a RAM (random memory) in which information necessary for executing programs is written and read. ●Access - Memory) 8.

As the external storage medium, a read-only nonvolatile storage medium such as a CD-ROM, and a writable and readable nonvolatile storage medium such as DAT (digital audio tape) are used. In addition,
The external storage medium is not limited to CD-ROM or DAT, but it is also possible to use a nonvolatile storage medium such as an IC card. The CD-ROM stores in advance map data obtained by digitizing (numerizing) each point on a road on a map. Information stored in this CD-ROM is read by a CD-ROM driver 10. CD-R
The read output of the OM driver 10 is decoded by the CD-ROM decoder 11 and sent to the bus line L.

On the other hand, the DAT is used as a so-called backup memory, and information is recorded or read by the DAT deck 12. When the vehicle power supply is cut off, information such as the current position coordinates of the vehicle stored in the RAM 9 immediately before is supplied to the DAT deck 12 via the DAT encoder/decoder 13 as backup data, and is stored in the DAT. DA when inputting
The stored information of T is read out by the DAT deck 12. The read information is sent to the DAT encoder/decoder 13
RAM by being sent to bus line L via
9 is stored.

Turning the vehicle power on and off is detected by a detection circuit 14 that monitors the output level of a so-called accessory switch SW of the vehicle. Vehicle power from a battery (not shown) that has passed through the accessory switch SW is stabilized by a regulator 15 and supplied as power to each part of the device. Due to the time constant of the circuit, the output voltage of the regulator 15 does not fall instantaneously when the accessory switch SW is turned off, and backup data is stored in the DAT as a backup memory during this falling period.

When the vehicle is running, the CPU 7 calculates the running direction of the vehicle based on the output data of the direction sensor 1 at a predetermined period by a timer interrupt, and calculates the running distance and The vehicle's current location coordinates are determined from the driving direction, map data of a certain area including the current location coordinates is collected from the CD-ROM, and the collected data is stored in the RAM as a buffer memory.
9 and supplies it to the display device 16.

The display device 16 includes a display 17 such as a CRT, and a V
(Video) - A graphic memory 18 consisting of RAM, etc., one graphic controller that draws map data sent from the system controller 5 as image data in the graphic memory l8 and outputs this image data, and this graphic controller. Display 17 based on image data output from one
It is composed of a display controller 20 that controls to display a map on the top. The input device 21 consists of a keyboard or the like, and issues various commands and the like to the system controller 5 by the user's keystrokes.

Next, the processing procedure for updating the distance correction coefficient R and the angle correction coefficient θ executed by the CPU 7 will be explained according to the flowchart shown in FIG.

Note that this subroutine corrects each output data of the direction sensor 1 and distance sensor 3 using the angle correction coefficient θ and the distance correction coefficient R, and recognizes the current location of the vehicle based on these corrected output data, including the current location. The main routine reads out a group of map data for a certain area from the CD-ROM and displays it on the display 17 as a map of the area around the current location of the vehicle, and also displays on the map the position of the own army indicating the current location of the vehicle. (not shown) is called and executed when the update menu for the distance correction coefficient R and the angle correction coefficient θ is selected by the manual key input of the manual device 21. In addition,
It is assumed that the current location recognition operation continues.

In addition, in this system, when it is detected that the vehicle has turned at an intersection, intersections near the current location are detected from map data using current location recognition, and this detected intersection is set as the current location on the map, so-called intersection pull-in is performed. shall be. The processing procedure for this intersection pull-in is described in detail in Japanese Unexamined Patent Publication No. 11813/1983.

First, the CPU 7 determines whether the vehicle has turned around an intersection (step Sl). For example, this judgment method is as follows:
The distance disclosed in the above-mentioned publications, etc., that is, the distance from the current location to the nearest position on the road segment based on current location recognition is determined from map data, and if this distance is smaller than a predetermined reference distance and the vehicle turns right or left. A method is used to detect when something has happened.

Note that the method for determining whether a vehicle is turning right or turning left is also described in the publication.

When it is determined that the vehicle has turned at an intersection, the CPU 7 calculates the inter-intersection distance J2Il between the currently detected intersection and the previously detected intersection based on the intersection lead-in and the distance between the current location and the currently detected intersection based on current location recognition, based on the map data, i.e. The distance M (hereinafter referred to as the pull-in distance) Δ1 corrected by the intersection pull-in is determined (step S2), and then the difference between the inter-intersection distance gI1 and the pull-in distance ΔD is determined as the vehicle's actual running distance Nr (step S3). ), and the ratio between the distance between intersections (lm) and the actual running distance 11r is determined as a provisional distance correction coefficient RO (step S4).

Next, the CPU 7 calculates the provisional distance correction coefficient R obtained up to that point.
Obtain the average and standard deviation of O (step S5), and then determine whether the number of samples is larger than the minimum number of samples (step S6). Determine whether the limit has been exceeded (step S7)
. If the number of samples does not exceed the maximum number of samples, C
PU7 determines whether the obtained standard deviation is below a certain value (
Step S8), if the standard deviation is below a certain value,
The distance correction coefficient R is updated, that is, the average value of the obtained provisional distance correction coefficients RO is set as a new distance correction coefficient R (step S9). If it is determined in step S7 that the number of samples exceeds the maximum number of samples, the program directly proceeds to step S9, or if it is determined in step S6 that the number of samples is less than the minimum number of samples, or in step S8 that the standard deviation has reached a constant value. When it is determined that the limit is exceeded, the program moves directly to step SIO. In step S1, if the intersection is not turned, the program moves to step SIO.

Note that the maximum sample is used to forcibly terminate the operation when the data has large variations and the deviation does not become small over a long distance.

Next, the CPU 7 calculates the angle θ of the road line segment (hereinafter referred to as road angle) where the current location is located based on the current location recognition (
Step S10), and then determine the running direction θr of the vehicle based on the output data of the direction sensor 1 (Step S11)
Then, the difference between the road angle θ and the running direction θr is determined as the angular deviation Δθ (step S12). Next, C.P.
U7 calculates the average and standard deviation of the angular deviations Δθ calculated so far (step S13), then determines whether the distance correction coefficient R has been updated (step S14), and determines whether the distance correction coefficient R has been updated or not. For example, it is determined whether the standard deviation of the angular deviation Δθ is less than or equal to a certain value (step S1
5). If the standard deviation of the angular deviation Δθ is below a certain value,
The angle correction coefficient θ is updated, that is, the average value of the obtained angle deviation Δθ is set as the new angle correction coefficient θ (step S16).
Then, it is determined whether the distance correction coefficient R has been updated (step S17). If it is determined in step S15 that the standard deviation of the angular deviation Δθ exceeds a certain value, or if it is determined in step S17 that the distance correction coefficient R has not been updated, the program returns to step S1. Step S
If it is determined in step S14 that the distance correction coefficient R has not been updated, the CPU 7 determines whether the angle correction coefficient θ has been updated (step S18), and if the angle correction coefficient θ has not been updated, the CPU 7 , the program moves to step S16.

If it is determined in step S17 and step S18 that the distance correction coefficient R and the angle correction coefficient θ have been updated, the CPU 7 ends a series of processes for updating the distance correction coefficient R and the angle correction coefficient θ. .

Effects of the Invention As explained above, in the in-vehicle navigation device according to the present invention, the difference between the distance between intersections flI1 obtained from map data and the pull-in distance Δg is determined as the actual traveling distance ρr of the vehicle, and the distance between intersections IIl1 and A provisional distance correction coefficient RO is determined based on the actual running distance flr, and the average value and standard deviation of a plurality of provisional distance correction coefficients RO obtained each time the vehicle turns at an intersection are determined. The configuration is such that the average value when the distance becomes the new distance correction coefficient R.

According to this, it is possible to always correct the output data of the distance sensor using the latest distance correction coefficient R.
This means that the distance traveled by the vehicle can always be accurately detected.

Regarding the angle correction coefficient θ, similarly, the output of the direction sensor is determined by the latest angle correction coefficient θ, which is set based on the angular deviation Δθ between the road angle θ obtained from the map data and the driving direction θr obtained from the direction sensor data. Since data can be corrected, the running direction of the vehicle can always be accurately detected.

Note that the above correction may be automatically executed after so-called one-rotation correction. By doing so,
It is possible to improve the accuracy.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the in-vehicle navigation device according to the present invention, and FIG. 2 is a flowchart showing a processing procedure for updating the distance correction coefficient R and the angle correction coefficient θ executed by the CPU. Explanation of symbols of main parts 1... Orientation sensor 3... Distance sensor 5... System controller

Claims (2)

[Claims] (1) A distance sensor that detects the traveling distance of the vehicle, a direction sensor that detects the traveling direction of the vehicle, a display means that displays an image according to the supplied display and information signal, and a road line segment on the map. reading means for reading a plurality of map data groups from a storage medium storing a plurality of map data groups including road data obtained by quantifying at least intersection positions and corresponding to a plurality of regions; and distance correction coefficient and angle correction. Correcting each output data of the distance sensor and the direction sensor using the coefficients, recognizing the current location of the vehicle based on these corrected output data, and extracting a map data group of a certain range of area including the current location from the storage medium. and a control means for controlling the extracted map data group and current location information to the display means as the display information signal to display a map around the current location of the vehicle and the current location, the control means for displaying the current location and a map of the vicinity of the vehicle's current location. An in-vehicle navigation device is configured to detect, from the road data, an intersection near the current location based on current location recognition by the control means when detected, and control the detected intersection to be set as the current location on a map, the control means calculates the inter-intersection distance between the currently detected intersection and the previously detected intersection based on the road data and the lead-in distance between the current location and the currently-detected intersection based on current location recognition, and calculates the difference between the inter-intersection distance and the lead-in distance. The difference is determined as the actual traveling distance of the vehicle, and a provisional distance correction coefficient is determined based on the distance between the intersections and the actual travel distance, and the average value of the plurality of provisional distance correction coefficients obtained each time the vehicle turns at the intersection, and An in-vehicle navigation device characterized in that a standard deviation is determined, and the average value when the standard deviation becomes a predetermined value or less is used as the distance correction coefficient. (2) a distance sensor that detects the travel distance of the vehicle; a direction sensor that detects the travel direction of the vehicle; a display means that displays an image according to the supplied display information signal; reading means for reading a plurality of map data groups from a storage medium storing a plurality of map data groups, each of which includes road data obtained by quantifying intersection positions and which corresponds to a plurality of regions; and a distance correction coefficient and an angle correction coefficient. is used to correct each output data of the distance sensor and the direction sensor, and to recognize the current location of the vehicle based on these corrected output data, and extract from the storage medium a map data group of a certain range of area including the current location. and a control means for controlling and supplying the extracted map data group and current location information to the display means as the display information signal to display a map around the current location of the vehicle and the current location, and detecting that the vehicle has turned around an intersection. When the above-mentioned control means detects an intersection near the current location based on the current location recognition from the road data, the in-vehicle navigation device controls the detected intersection to be the current location on the map. , determine the road angle of the current location based on current location recognition from the road data, determine the driving direction of the vehicle based on the output data of the direction sensor, determine the difference between the road angle and the driving direction as an angular deviation, and determine when the vehicle is at an intersection. An in-vehicle navigation system characterized in that a plurality of average values and standard deviations of the angular deviations obtained each time the vehicle turns are determined, and the average value when the standard deviation becomes a predetermined value or less is used as the angle correction coefficient. Device.