JPH0786735B2 - Car navigation system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vehicle-mounted navigation device.

BACKGROUND ART In recent years, map data including road data obtained by digitizing each point on the road of a map is stored in a storage medium such as a CD-ROM, and a certain range including the current position of the vehicle while recognizing the current position of the vehicle. The in-vehicle navigation device that reads out the map data group of the area from the storage medium and displays it on the display as a map around the current location of the vehicle and automatically displays the vehicle position indicating the current location of the vehicle on the map,
It is being put to practical use.

In such an on-vehicle navigation device, the distance sensor measures the traveling distance of the vehicle and the direction sensor measures the traveling direction of the vehicle, and the present position of the vehicle on the map is estimated from the traveling distance and the traveling direction. By the way, in the distance sensor and the azimuth sensor, it is unavoidable that an error occurs in the output data obtained due to their accuracy, so it is necessary to correct the output data using the correction coefficient.

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

Further, although the geomagnetic sensor is mounted with the traveling direction of the vehicle and the direction of the sensor aligned at the time of mounting, an error occurs at the time of mounting, and it is still necessary to adjust each vehicle.

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

As a method of this correction, for example, a method disclosed in Japanese Patent Laid-Open No. 62-140018 is known, but it is difficult for such a correction method to perform accurate correction once. Further, since it is necessary to input the position and the like, the operation becomes complicated, and a simpler method is required.

Further, the error of the traveled distance obtained by the distance sensor may be not only due to the accuracy of the sensor but also due to wear of the tire, air pressure of the tire, slip or the like. Therefore, if the distance correction coefficient once set is always used, the traveling distance cannot always be accurately obtained.

Also, even when using a geomagnetic sensor that detects the direction of the vehicle based on the geomagnetism (earth magnetic field) as the orientation sensor, the north indicated by this geomagnetic sensor is not the map north,
The output data of the geomagnetic sensor is corrected using the azimuth correction coefficient. However, since the azimuth correction coefficient changes depending on the region, if the azimuth correction coefficient is always constant, the traveling azimuth 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 detect the traveling distance and traveling direction of a vehicle by always setting the latest distance correction coefficient and heading correction coefficient.

In the vehicle-mounted navigation device according to the present invention, the current position of the vehicle is recognized based on each output data of the distance sensor and the azimuth sensor, the map data of a certain range including the current position is extracted from the storage medium, and the map around the current position of the vehicle is extracted. In the navigation device for displaying the current location, when it is detected that the vehicle has turned at the intersection, the intersection near the current location by current location recognition is detected from the map data, and the detected intersection is set as the current location on the map. Based on the distance between the current detected intersection and the previously detected intersection based on the current location, and the retract distance between the current location and the currently detected intersection based on the recognition of the current location, the actual running distance of the vehicle is calculated based on the distance between the intersection and the retract distance. Then, the temporary distance correction coefficient is calculated based on the distance between the intersections and the actual running distance, and the vehicle is at the intersection. A plurality of average values and standard deviations of the provisional distance correction coefficient obtained each time the vehicle bends are obtained, and the average value when the standard deviation becomes a predetermined value or less is set as a distance correction coefficient, and the distance sensor is determined by the distance correction coefficient. The output data of is corrected.

Further, in the vehicle-mounted navigation device according to the present invention, the current position of the vehicle is recognized based on the output data of each of the distance sensor and the direction sensor, and the map data of a certain range including the current position is extracted from the storage medium, and the surrounding area of the current position of the vehicle is detected. In a navigation device that displays a map and a current location, when it is detected that a vehicle has turned an intersection, an intersection near the current location is detected by the current location recognition from the map data, and the detected intersection is set as the current location on the map, and the current location is recognized. The road angle of the present location is obtained from the map data, and the traveling direction of the vehicle is obtained based on the output data of the direction sensor, and the difference between the road angle and the traveling direction is obtained as an angle deviation, and each time the vehicle turns an intersection. Obtain a plurality of average values and standard deviations of the obtained angle deviations, and find the standard deviations. The average value when it becomes the value or less and the angle correction coefficient has a configuration for correcting the output data of the azimuth sensor by the angle correction factor.

Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a vehicle-mounted navigation device according to the present invention. In the figure, 1 is a direction sensor for detecting the traveling 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 traveling distance of the vehicle, 4 is latitude and longitude information. GPS (GlobalPos) to detect the absolute position of the vehicle from
itioning system) 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, geomagnetism (earth magnetic field)
A geomagnetic sensor is used to detect the traveling direction of the vehicle.

The system controller 5 receives the detection outputs of the sensors (devices) 1 to 4 as an input and performs an A / D (analog / digital) conversion process and the like, and various image data processes and is sequentially sent from the interface 6. Based on the output data of the respective sensors (devices) 1 to 4, the traveling distance, traveling direction, and current position coordinates (longitude,
A CPU (central processing circuit) 7 for performing calculations such as latitude), a ROM (read only memory) 8 in which various processing programs of the CPU 7 and other necessary information are written in advance,
RAM (Random Access Memory) 8 where information necessary for executing the program is written and read
It consists of and.

As an external storage medium, for example, a read-only non-volatile storage medium such as a CD-ROM, and as a writable and readable non-volatile storage medium such as a DAT (digital
Audio tape) is used. The external storage medium is not limited to a CD-ROM or DAT, and a non-volatile storage medium such as an IC card can be used. The CD-ROM stores in advance map data obtained by digitizing (numericalizing) each point on the road of the map. This CD-RO
The information stored in M is read by the CD-ROM driver 10. The read output of the CD-ROM 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 recording or reading of information is performed by the DAT deck 12
Done by. Immediately before turning off the vehicle power
Information such as the vehicle's current position coordinates stored in RAM9 is stored as backup data in the DAT by being supplied to the DAT deck 12 via the DAT encoder / decoder 13, and when the vehicle power is turned on, the stored DAT information is stored in the DAT. Deck 12
Read by. The read information is stored in the RAM 9 by being sent to the bus line L via the DAT encoder / decoder 13.

The turning on and off of the vehicle power is detected by the detection circuit 14 which monitors the output level of the 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 the regulator 15 and supplied as power to each part of the device. The output voltage of the regulator 15 does not fall instantaneously when the accessory switch SW is turned off due to the time constant of the circuit, and backup data is stored in the DAT as the backup memory during this fall period.

When the vehicle is traveling, the CPU 7 calculates the traveling azimuth of the vehicle based on the output data of the azimuth sensor 1 at a predetermined cycle by a timer interruption, and the traveling distance and the traveling distance by interruption every constant distance traveling based on the output data of the distance sensor 3. Obtain the coordinates of the current position of the vehicle from the traveling direction, collect map data of a certain range of areas including the coordinates of the current position from the CD-ROM, and temporarily store the collected data in the RAM 9 as a buffer memory and on the display device 16. Supply.

The display device 16 includes a display 17 such as a CRT and a V (Video).
A graphic memory 18 including a RAM, a graphic controller 19 for drawing map data sent from the system controller 5 as image data in the graphic memory 18, and outputting the image data; and a graphic controller 19 for outputting the graphic data. The display controller 20 controls to display a map on the display 17 based on the image data. The input device 21 is composed of a keyboard and the like, and issues various commands to the system controller 5 by key input by the user.

Next, the processing procedure for updating the distance correction coefficient R and the angle correction coefficient θ executed by the CPU 7 will be described with reference to the flowchart of FIG. Note that this subroutine corrects each output data of the azimuth sensor 1 and the distance sensor 3 using the angle correction coefficient θ and the distance correction coefficient R, recognizes the current position of the vehicle based on these corrected output data, and includes the current position. CD-RO for map data of a certain area
Input from during execution of the main routine (not shown) that reads from M and displays on the display 17 as a map around the current position of the vehicle and displays the own vehicle position indicating the current position of the vehicle on the map. The distance correction coefficient R and the angle correction coefficient θ are entered by a key input from the device 21.
Shall be called and executed when the update menu of is selected. It is assumed that the current position recognition operation is still being performed.

In addition, in this system, when it is detected that a vehicle turns an intersection, the intersection near the current location is detected from the map data by the current location recognition, and the so-called intersection pull-in is performed in which the detected intersection is the current location on the map. And Regarding the processing procedure for pulling in this intersection, see
It is described in detail in Japanese Patent Laid-Open No. 63-11813.

The CPU 7 first determines whether or not the vehicle has made a turn at the intersection (step S1). As this determination method, for example, the method disclosed in the above publication or the like, that is, the distance from the current location to the nearest position on the road segment by the current location recognition is obtained from the map data, and this distance is smaller than the predetermined reference distance And a method of detecting that the vehicle has turned right or left is used. In addition, regarding the method of judging whether the vehicle is turning right or left,
It is described in the publication.

When it is determined that the vehicle has made a turn at the intersection, the CPU 7 causes the intersection distance lm between the presently detected intersection and the previously detected intersection based on the map data, and the distance between the present location and the presently detected intersection by recognizing the present location, that is, A distance (hereinafter referred to as a pull-in distance) Δl which is corrected by pulling in at the intersection is obtained (step S2), and subsequently, a difference between the intersection distance lm and the pull-in distance Δl is obtained as an actual running distance lr of the vehicle (step S3). , Furthermore, distance between intersections lm and actual running distance
Calculate the ratio with lr as the provisional distance correction coefficient R ₀ (step
S4).

Subsequently, the CPU 7 obtains the average and standard deviation of the provisional distance correction coefficients R ₀ obtained so far (step S5), and then determines whether the number of samples is larger than the minimum number of samples (step S6), If so, then it is determined whether the number of samples exceeds the maximum number of samples (step S7). If the number of samples does not exceed the maximum number of samples, the CPU 7 determines whether or not the obtained standard deviation is less than or equal to a certain value (step S8). If the standard deviation is less than or equal to the certain value, the distance correction coefficient R is updated. That is, the average value of the calculated provisional distance correction coefficient R ₀ is set as a new distance correction coefficient R (step S9). When it is determined in step S7 that the number of samples exceeds the maximum number of samples, the program directly proceeds to step S9, and when it is determined in step S6 that the number of samples is less than or equal to the minimum number of samples, or the standard deviation is constant in step S8. When it is determined that the number exceeds the limit, the program directly proceeds to step S10. If the intersection is not bent at step S1, the program proceeds to step S10.

The maximum sample is for forcibly ending the operation when the variation in data is large and the deviation does not decrease over a long distance.

Next, the CPU 7 obtains an angle (hereinafter, referred to as a road angle) θm of a road segment where the current position is located by recognizing the current position (step S10), and then, based on the output data of the direction sensor 1, a traveling direction θr of the vehicle. Then, the difference between the road angle θm and the traveling direction θr is obtained as an angle deviation Δθ (step S12). Subsequently, the CPU 7 obtains the average and standard deviation of the angle deviations Δθ obtained so far (step S13), then determines whether or not the distance correction coefficient R has been updated (step S14), and the distance correction coefficient R is updated. If so, it is determined whether or not the standard deviation of the angular deviation Δθ is less than or equal to a certain value (step S15). If the standard deviation of the angle deviation Δθ is less than or equal to a certain value, the angle correction coefficient θ is updated, that is, the average value of the obtained angle deviation Δθ is set as a new angle correction coefficient θ (step S16), and then the distance correction coefficient R is It is determined whether or not it has been updated (step S17). If it is determined in step S15 that the standard deviation of the angle 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. When 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). If the angle correction coefficient θ has not been updated, , The program is step S16
Move to. When it is determined in step S17 and step S18 that the distance correction coefficient R and the angle correction coefficient θ have already been updated, the CPU 7 ends the series of processes for updating the distance correction coefficient R and the angle correction coefficient θ. .

As described above, in the vehicle-mounted navigation device according to the present invention, the distance between intersections obtained from map data
The difference between lm and the pull-in distance Δl is obtained as the actual running distance lr of the vehicle, and the provisional distance correction coefficient R ₀ is obtained based on the inter-intersection distance lm and the actual running distance lr, and is obtained each time the vehicle turns the intersection. The average value and the standard deviation of the plurality of provisional distance correction coefficients R ₀ are calculated, and the average value when the standard deviation becomes a predetermined value or less is set as a new distance correction coefficient R.

According to this, since the output data of the distance sensor can be constantly corrected by the updated distance correction coefficient R,
Therefore, the traveling distance of the vehicle can always be detected accurately.

Similarly, regarding the angle correction coefficient θ, the output data of the azimuth sensor based on the latest angle correction coefficient θ set based on the angle deviation Δθ between the road angle θm obtained from the map data and the traveling azimuth θr obtained from the azimuth sensor data. Therefore, the traveling direction of the vehicle can always be detected accurately.

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

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an in-vehicle navigation device according to the present invention, and FIG. 2 is a flow chart showing a processing procedure for updating a distance correction coefficient R and an angle correction coefficient θ executed by a CPU. Explanation of symbols of main parts 1 ... Direction sensor, 3 ... Distance sensor 5 ... System controller 10 ... CD-ROM driver 16 ... Display device, 17 ... Display

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsuhiko Fukushima 25 Nishi-machi, Yamada, Kawagoe City, Saitama Prefecture 1 Pioneer Co., Ltd. Kawagoe Factory (56) Reference JP-A-61-17911 (JP, A) Flat 1-21315 (JP, A) US Patent 2745195 (US, A)

Claims (2)

[Claims] 1. A current position of a vehicle is recognized based on output data of a distance sensor and a direction sensor, map data of a certain range including the current position is extracted from a storage medium, and a map around the current position of the vehicle and the current position are displayed. In the navigation system, when it is detected that the vehicle has turned at an intersection, an intersection in the vicinity of the current location is detected by the current location recognition from the map data, and this detected intersection is set as the current location on the map, and the current time is detected based on the map data. The inter-intersection distance between the intersection and the previously detected intersection and the pull-in distance between the current location and the current detected cross-section by recognizing the current location are obtained, and the actual running distance of the vehicle is obtained from the inter-intersection distance and the pull-in distance. The provisional distance correction coefficient is obtained based on the inter-distance and the actual traveling distance, and the provisional distance obtained each time the vehicle turns an intersection. Obtaining a plurality of average values and standard deviations of the correction coefficient, the average value when the standard deviation becomes a predetermined value or less is a distance correction coefficient, and the output data of the distance sensor is corrected by the distance correction coefficient. A featured in-vehicle navigation device. 2. A current position of a vehicle is recognized based on each output data of a distance sensor and a direction sensor, a certain range of map data including the current position is extracted from a storage medium, and a map around the current position of the vehicle and the current position are displayed. In the navigation system, when it is detected that the vehicle has turned an intersection, an intersection near the current location by current location detection is detected from the map data, and this detected intersection is set as the current location on the map, and the road angle of the current location by current location recognition is determined. The traveling azimuth of the vehicle is obtained based on the output data of the azimuth sensor in addition to the map data, the difference between the road angle and the traveling azimuth is obtained as an angular deviation, and the angular deviation obtained each time the vehicle turns an intersection. Of a plurality of average values and standard deviations, and the average value when the standard deviation becomes a predetermined value or less As the correction coefficient, the vehicle-mounted navigation device and corrects the output data of the azimuth sensor by the angle correction factor.