JPH0795221B2 - 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 has been stored in a storage medium such as a CD-ROM, and a certain range including the current position 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 as a map around the current location of the vehicle on the display and automatically displays the vehicle position indicating the vehicle's current location on the map has been developed and put into practical use. Is being done.

Such an on-vehicle navigation device has a configuration in which a traveling direction of the vehicle is obtained by a direction sensor and a traveling distance of the vehicle is obtained by a distance sensor, and the current position of the vehicle on the map is estimated from the traveling direction and the traveling distance. here,
Since both the azimuth data and the distance data obtained by the azimuth sensor and the distance sensor usually include an error of about several percent, the current position of the vehicle estimated from these data inevitably causes an error with respect to the actual traveling position. Will have.
For this reason, in the vehicle-mounted navigation device, the current location is constantly corrected by so-called map matching processing in which the current location of the vehicle is drawn onto the road in the vicinity every time the vehicle travels a certain distance (or a certain time).

By the way, as a direction sensor, a geomagnetic sensor that detects the direction of a vehicle based on the geomagnetism (earth magnetic field) is known. This geomagnetic sensor is easily affected by the disturbance magnetic field, and the accurate orientation cannot be detected due to the effect of the magnetization of the vehicle body when the vehicle passes through a railroad crossing, for example.
In such a case, the output data of the geomagnetic sensor is corrected. However, if this correction process is not sufficient, or if you drive on a road with no map data, you will travel for a long time without finding a road segment in the vicinity. Since it is not performed, the current position will be greatly deviated from the actual traveling position and will be inaccurate.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an in-vehicle navigation device that can deal with a recognition error of the current position of a vehicle.

The vehicle-mounted navigation device according to the present invention includes display means for displaying an image in accordance with the supplied display information signal and road data obtained by digitizing each point on the road line segment of the map, and includes a plurality of areas. A reading means for reading the map data group from a storage medium in which a plurality of corresponding map data groups are stored, and a recognition range for recognizing the current position and direction of the vehicle, and a predetermined range including the recognized current position obtained by this The reading means is controlled to extract a map data group of a region from the storage medium, and the extracted map data group and current location information are supplied to the display means as the display information signal to obtain a map around the current location of the vehicle and the current location. A control means for displaying, and a road near the recognized current location based on the road data of the map data group of the area of the predetermined range by the control means. Minutes to the recognized current position and the angle of the neighboring road line segment with respect to the azimuth of the vehicle obtained by the recognition processing satisfies a predetermined condition, the current position to be displayed should be corrected on the neighboring road line segment. An in-vehicle navigation device for controlling the display means, wherein the control means, when the distance and angle do not satisfy the predetermined condition over a predetermined traveling distance or a predetermined traveling time,
It is characterized in that a display information signal is supplied to the display means in order to display that the recognition present position is incorrect.

That is, according to the vehicle-mounted navigation device of the present invention,
When the distance from the road segment near the recognition current position to the recognition current position and the angle of the road segment near the recognition current position with respect to the direction of the vehicle satisfying a predetermined condition satisfy a predetermined condition, the current position to be displayed is set on the road segment near the current position. In the map matching to be corrected, when the distance and the angle do not satisfy the predetermined condition for the predetermined traveling distance or the predetermined traveling time, it is displayed that the recognition present position is incorrect.

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 (Global Po
sitioning 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 the external storage medium, a read-only non-volatile storage medium such as a CD-ROM and a writable and readable non-volatile storage medium such as a DAT (digital audio tape) are 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 contains
Map data obtained by digitizing (numerizing) each point on the road of the map is stored in advance. This CD-ROM is a CD
-The ROM driver 10 reads the stored information. The read output of the CD-ROM driver 10 is the CD-ROM decoder 11
Is decoded by and transmitted 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 sent to the balance line L via the DAT encoder / decoder 13 to be stored in the RAM 9.

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 rise 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 a 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. The present position coordinates of the vehicle are obtained from the traveling direction, the map data of a certain area including the present position coordinates is collected from the CD-ROM, and the collected data is temporarily stored in the RAM 9 as the buffer memory and displayed on the display device 16. Supply.

The display device 16 includes a display 17 such as a CRT and a V (Video).
-Graphic memory 18 including RAM and the like, graphic controller 19 that draws map data sent from system controller 5 as image data in graphic memory 18 and outputs this image data, and output from this graphic controller 19 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.

FIG. 2 shows an example of the arrangement of various operation key groups in the input device 21. The operation key groups are arranged in four directions of a cursor (not shown) displayed on the display 17 in the upper, lower, left and right directions of the screen. 4 cursor keys to move to 22U,
22D, 22L, 22R, and a set key 24 for issuing a command for resetting an ambiguous flag and an ambiguous counter or for correcting the current position and a direction, which will be described later, and a clear key 24 for issuing a command for only correcting the current position.

Next, the processing procedure executed by the CPU 7 when it is detected that the current position is ambiguous (inaccurate) by the current position recognition of the vehicle will be described with reference to the flowcharts of FIGS. 3A and 3B. It should be noted that this subroutine is called and executed each time the vehicle runs a certain distance (or a certain time) during the processing of the main routine (not shown). In addition, it is assumed that a map of a certain area centering on the current position of the vehicle is displayed on the display 17.

The CPU 7 first obtains the coordinates Ps (Xs, Ys) of the current position based on the output data of the distance sensor 3 and the traveling azimuth θs based on the output data of the azimuth sensor 1 (step S1). Point on road segment near current location, as shown
The distance la to Pa (Xa, Ya) and the angle θa of the line segment are calculated (step S2), and the calculated distance la is then a predetermined value lth.
It is determined whether or not the deviation of the traveling direction of the current position with respect to the neighboring road line segment, that is, | θs−θa | is equal to or less than the predetermined value θth is satisfied (step S3).

If the road segment near the current location satisfies the above conditions, that is, la ≦ lth and | θs−θa | ≦ θth, the CPU 7 sets the current location to the point Pa (Xa, Ya) on the road segment near the current location. It is corrected (step S4), and then the ambiguous counter described later is reset (step S5). If the road segment near the current location does not satisfy the above condition, it is determined that the current location by the current location recognition may be ambiguous, and the count value N of the ambiguous counter that counts the number of determinations is incremented ( Step S6), and subsequently, it is determined whether or not the count value N is a predetermined value Nth or more (step S6).
7). If N ≧ Nth, the CPU 7 determines that the current location by the current location recognition is ambiguous, and sets an ambiguous flag (step S8).

After resetting the fuzzy counter in step S5, after determining that N <Nth in step S7, or in step S8
After setting the ambiguous flag, the CPU 7 determines whether or not the ambiguous flag is set (step S
9). If the ambiguous flag is not set, the program returns to the main routine. If the ambiguous flag is set, the CPU 7 controls the display device 16 to display on the display 17 that the present position is ambiguous (step S10). On the display 17, a map of a certain area centering on the current location is displayed, and as shown in FIG. 5, a vehicle mark, a direction mark, and a circle with a predetermined radius centering on the vehicle position are displayed. In S10, the display color indicating that the current position is ambiguous is displayed by changing the display color of the circle normally displayed in yellow, for example, to red. The display that the present location is ambiguous is not limited to this display method,
For example, various messages such as displaying a message on the display 17 are possible.

After displaying that the current position is ambiguous, the CPU 7 controls the display device 16 to display a message on the display 17 for instructing the driver to input the current position and direction of the vehicle (step S11). ), And then waits for a key input to input the current location and direction (step S12). When a message for inputting the current location and direction is displayed on the display 17, the driver actually moves the vehicle to a place on the map displayed on the display 17 where it is easy to confirm the position, and the current location and You will need to enter the bearing. This input is performed by the key input in the operation key group shown in FIG. 2 so that the own vehicle mark on the diff play 17 is located at the current position on the map and the direction mark matches the road direction at that position. The processing procedure associated with the key input is shown below.

When the CPU determines that there is a key input in step S12, it first determines whether or not the input key is the set key 23 (step S13), and if it is the set key input, resets the fuzzy flag and the fuzzy counter (step S14),
Then, the message for inputting the current location and direction and the display indicating that the current location is ambiguous are deleted (step S15). After that, the program returns to the main routine. If the input key is not the set key 23, the CPU 7 waits for key input by the cursor keys 22U, 22D, 22L, 22R (step S16).

If there is a cursor key input, the CPU 7 moves a cursor (not shown) indicating the vehicle position displayed on the display 17 relative to the displayed map in response to the key input (actually, the map The display device 16 is controlled so that it is executed by scrolling (step S17), and then the key input is monitored again (step S18). If there is another cursor key input (step S19), the program returns to step S17 and repeats the cursor position changing process according to the key input.

Subsequently, the CPU 7 determines whether or not the key input after the cursor key input is the set key input (step S20),
If it is not the set key input, it is determined whether or not the key input is the clear key input (step S21). If it is not the clear key input, the program returns to step S18 and repeats the above processing. If clear key input,
Correct the vehicle position on the map to the cursor position (step
S22). After that, the program returns to the main routine. That is, only the correction of the current location is performed by the clear key input after the cursor key input is completed.

When it is determined in step S20 that the key input is a set key input, the CPU 7 corrects the vehicle position on the map to the cursor position (step S23), and then waits for key input (step S2).
Four). If there is a key input, the CPU 7 determines whether or not the input key is a cursor key (step S25), and if it is a cursor key input, depending on the key input, for example, in the case of the left cursor key 22L, The display device 16 is controlled to rotate the direction mark in the counterclockwise direction and in the case of the right cursor key 22R in the clockwise direction (step S26). After the azimuth input with the cursor keys is completed, the CPU 7 determines whether the following key input is a set key input (step S27). If the input is not the set key, the program returns to step S24 and repeats the above processing. CP for set key input
U7 executes the processing for azimuth correction (step S28), after which the program returns to the main routine. In other words, by entering the set key after the cursor key input is completed, the process proceeds to a processing routine for correcting the current position and the direction. Therefore, for example, when a geomagnetic sensor is used as the orientation sensor 1, if it is determined that the current position is ambiguous after passing the railroad crossing, it is determined that the current position is ambiguous because the output data of the geomagnetic sensor is not corrected accurately. It is sufficient to make a judgment and perform a key operation so as to enter this processing routine.

Here, how to obtain the traveling direction of the vehicle when the geomagnetic sensor is used as the direction sensor 1 will be described. A geomagnetic sensor is generally composed of a pair of magnetic detection elements arranged on the same plane with a phase angle of 90 ° to each other. One of the pair of elements detects, for example, a geomagnetic component in the U direction (north direction), and the other one. The geomagnetic component in the V direction (east direction) is detected. When the geomagnetic sensor having such a configuration is rotated once on a horizontal plane, the output data from both the U and V detection elements causes
A locus of a circle I centering on the origin O of the UV orthogonal coordinate system can be drawn. Therefore, for example, the counterclockwise azimuth angle θ from the east (V axis) at the point P (U ₁ , V ₁ ) should be calculated from the equation θ = tan ⁻¹ (U / V) (1) You can

Therefore, such a geomagnetic sensor is attached to the vehicle at a predetermined angle with respect to the front-rear direction or the left-right direction of the vehicle, and the calculation of formula (1) is performed based on the output data from both the U and V detection elements. By doing so, the traveling direction of the vehicle can be obtained.

By the way, it is ideal that only the magnetic flux due to the earth's magnetic field exists around the geomagnetic sensor, but in the vehicle,
There is generally an extra magnetic flux due to the magnetization of the body steel plate. For this reason, a method of performing accurate azimuth detection by removing the influence of the magnetization of the vehicle body (see, for example, Japanese Patent Laid-Open No. 57-28208) is adopted. In this method, when the U, V magnetic detection element is fixed to the vehicle and there is no relative displacement between the two, the center of the circle drawn by plotting the output obtained by turning the magnetic detection element once, In consideration of the fact that the distance from the coordinate origin is due to the effect of body magnetization, the output data obtained from both detection elements are corrected so that the center of the drawn circle moves to the origin, and the body The effect of magnetism is removed.
More specifically, the circle II drawn by the outputs of both detection elements is at a position where the center Q of the circle II is moved from the origin, as shown in FIG. Therefore, the maximum value Umax, Vmax and the minimum value of the output U, V of both detection elements
Umin and Vmin are obtained, and the coordinate of the center Q is calculated from these by the following equation (2).

The calculated center values Uo, Vo are used to correct the output values U, V of the magnetic detection elements by the following equation (3), and the azimuth is calculated from the corrected center values U ', V'. is there.

The center values Uo, Vo and the radius r are obtained in advance by so-called one-turn correction when the system is started up, that is, by making one turn of the vehicle equipped with the geomagnetic sensor.

Next, a sub-routine for performing the processing for correcting the bearing will be described with reference to the flowchart of FIG.

The CPU 7 obtains the angle information θs from the azimuth information input by the driver in the process of step S25 in FIG. 3B (step S71), and then outputs data of the azimuth sensor (geomagnetic sensor) 1 (hereinafter referred to as sensor data). ) MX, MY are taken in (step S72), and then the sensor data MX, MY
Whether the MY is stable or not
Judgment is made based on whether or not the difference between the current value of X and MY and the previous value is continuously less than a predetermined value a predetermined number of times (step S7).
3). If you determine that the sensor data MX, MY are stable,
The CPU 7 obtains the average coordinate values MXm, MYm of the sensor data MX, MY fetched a predetermined number of times (step S74), and then from this coordinate value MXm, MYm, the circle radius Ro and the angle information θs (4)
Based on the formula, new center values MXon, MYo as shown in FIG.
Find n (step S75).

The radius Ro of the circle is obtained in advance by one rotation correction when the system is started up. Next, the CPU 7 corrects the sensor data by using the new center values MXon and MYon instead of the center values MXo and MYo up to then, and detects the direction from the corrected value (step S76), and then corrects the center value. The process of is executed (step S77). After that, the program returns to the main routine.

Next, the subroutine for performing the center value correction process will be described with reference to the flowchart of FIG. In addition,
In this process, if the center value is corrected once by the driver based on the azimuth information manually input, there is a risk of erroneous correction. Therefore, it is necessary to confirm whether the center value is accurate. It is done.

The CPU 7 first obtains the angle θm of the road segment of the current location on the map data (step S91), then takes in the sensor data MX, MY (step S92), and then obtains the current value of the angle θm of the road segment. It is determined whether the difference from the previous value is less than a certain value (step S93) or whether the difference between the current value and the previous value is less than a certain value (steps S94, S95) for each of the sensor data MX, MY. . If all the conditions are satisfied, the CPU 7 increments the determination counter (step S96), and subsequently determines whether or not the count value N is equal to or more than the predetermined value Nth (step S97). N
<Nth, the program returns to step S91.

If N ≧ Nth, CPU 7 causes sensor data MX, MY, radius of circle
The center values MXo and MYo are calculated from Ro and the angle information θm based on the above equation (4) (step S98), and then the center values MXo and MYo are calculated.
The standard deviation σ of MYo is calculated (step S99), and it is determined whether or not this standard deviation σ is less than or equal to a predetermined value σth (step S1
00), if σ ≦ σth is not satisfied, the current value of the angle information θm and the sensor data MX, MY is set to the previous value, and the determination counter is reset (step S101), after which the program returns to step S91. If the conditions are not met in any of steps S93 to S95, the program directly
Move to S101. When it is determined in step S100 that σ ≦ σth, the CPU 7 obtains the average of the center values MXo and MYo and corrects the center value as new center values MXo and MYo (step S102).

Effects of the Invention As described above, according to the vehicle-mounted navigation device of the present invention, the distance from the neighboring road line segment of the recognition current position to the recognition current position and the angle of the neighboring road line segment with respect to the azimuth of the vehicle obtained by the recognition process are When satisfying a predetermined condition, in map matching that corrects the current location to be displayed on the neighboring road line segment, when these distances and angles do not satisfy the predetermined condition over a predetermined traveling distance or a predetermined traveling time, Recognition It is displayed that the current location is incorrect.

As a result, the driver can take prompt action such as correcting the present location by looking at this display.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an in-vehicle navigation device according to the present invention, FIG. 2 is a diagram showing an example of an arrangement of operation key groups in an input device, and FIGS. 3A and 3B show the current position by recognizing the current position of the vehicle. A flowchart showing the processing procedure when ambiguous is detected, Fig. 4 shows the coordinates of the current location
Figure 5 shows the relationship between Ps (Xs, Ys) and traveling direction θs, the distance la to the point Pa (Xa, Ya) on the neighboring road line segment, and the angle θa of the line segment. The figure which shows an example of the structure of the display screen which shows a running direction, FIG. 6 is the diagram which shows the locus | trajectory which the output data of a geomagnetic sensor draws, FIG. 7 is the flowchart which shows the process procedure of direction correction, FIG. FIG. 9 is a diagram showing the relationship between the value coordinates and the new center value coordinates, and FIG. 9 is a flowchart showing the processing procedure of the center value correction. 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 front page (72) Inventor Kazuhiro Akiyama 25 Nishimachi, Yamada, Kawagoe City, Saitama Prefecture 1 Pioneer Co., Ltd. Kawagoe factory (56) Reference JP-A-60-79499 (JP, A) JP 58-27011 (JP, A) JP-A-1-41997 (JP, A)

Claims (1)

[Claims] 1. A display means for displaying an image in accordance with a supplied display information signal and road data obtained by digitizing points on a road segment of a map and corresponding to a plurality of regions. A reading unit that reads the map data group from a storage medium that stores a plurality of map data groups, and a map of a predetermined range including the recognized current position obtained by performing recognition processing for recognizing the current position and direction of the vehicle. Control for controlling the reading means to extract a data group from the storage medium and supplying the extracted map data group and current position information to the display means as the display information signal to display a map around the current position of the vehicle and the current position. And a means for calculating the distance from the road segment near the recognized current location to the recognized current location based on the road data of the map data group of the area in the predetermined range by the control means. And the angle of the near road line segment with respect to the azimuth of the vehicle obtained by the recognition processing satisfies a predetermined condition, the display means is controlled to correct the current position to be displayed on the near road line segment. The in-vehicle navigation device, wherein the control means displays that the recognized current position is incorrect when the distance and the angle do not satisfy the predetermined condition for a predetermined traveling distance or a predetermined traveling time. An on-vehicle navigation device, characterized in that a display information signal is supplied to the display means.