JPS63168508A - Navigation apparatus - Google Patents

Abstract

PURPOSE:To accurately inform the present position, by storing map data of the coordinates of a straight road, wherein the distance between the inflection points of a road is set to min. unit, and the road angle to a reference azimuth and estimating the present own position from the distance data from the inflection points and the road angle to synthesize said position with the map data before displaying the same. CONSTITUTION:The map data stored in an image memory 7 is read from an external memory apparatus 4 by a central operational processing unit (16-bit CPU) 6 to be displayed on a display part 9. A driver inputs a starting point, an advancing direction and a start commend to a keyboard 3. CPU 6 calculates the present position from the map data on the basis of the road angle of the straight line between inflection points A, B to display the same on the display device 9 along with a map. The calculated position is present on the segment AB and not shifted therefrom. If necessary, processing returning the position display to the passed inflection point B is performed to remove the cumulated error contained in a running distance. When a car reaches the point B, the road angle is altered to the road angle formed by segment B, C and the integration of the running distance is reset to be reopened. The operation specifying a running branch road is performed at a crossing. By this constitution, the estimation operation of the present own position is certainly performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a navigation device that estimates the current position of its own vehicle, synthesizes this estimated position with a map, and displays it on a display unit, and particularly relates to a navigation device that estimates the current position of its own vehicle, synthesizes this estimated position with a map, and displays it on a display unit, and in particular, The present invention relates to a navigation device that prevents position display from shifting.

[Conventional technology]

A navigation device calculates the current location of a vehicle, combines this current location information with map information read from a storage device, and supplies the combined information to a display unit, thereby displaying the current location and its travel trajectory. Such a navigation device facilitates confirmation of the current position of the own vehicle by reading a mark indicating the current position displayed on a display section inside the vehicle in relation to a displayed map.

When a navigation device is used as a driving aid when driving around tourist spots or delivering goods to uncharted areas, it is possible to drive while knowing the current location of the vehicle at all times, allowing for efficient travel to the destination. This makes it possible to drive comfortably.

Here, there are two types of navigation devices: those that use dead reckoning navigation and those that use radio navigation. Deadhead navigation uses distance information obtained from a mileage sensor and a direction sensor such as a gyro sensor or geomagnetic sensor mounted on the vehicle. By calculating the obtained azimuth information, the current position is estimated based on the position information at the time of departure inputted at the time of departure. On the other hand, radio navigation determines the position of the vehicle by receiving and calculating special radio waves emitted from artificial satellites, radio towers, etc.

[Problem that the invention seeks to solve]

To calculate the current position in conventional navigation devices, dead reckoning navigation or radio navigation as described above is used, but geomagnetic sensors to obtain azimuth information used for dead reckoning navigation are used at railroad crossings and power lines. In addition to receiving large electromagnetic disturbances,
Errors may also be included in the output signal due to changes in the amount of magnetization of the vehicle body. As a result, as the travel distance from the departure point increases, the error included in the estimated current position increases. If the error included in the current position determined by this estimation increases, the current position displayed on the display and the driving trajectory will deviate from the road part on the displayed map, and will be located in a field part, for example. This will cause inconvenience. Similarly, when a gyro sensor is used as the azimuth sensor, accumulation of azimuth errors is unavoidable, and as the travel distance increases, the estimation error of the current position increases.

In addition, when radio navigation is used, it is possible to calculate the current position with high precision, but the radio wave receiving device and signal processing device installed in the vehicle are complicated and expensive, and the The problem is that it becomes unusable when driving in areas where radio waves cannot be received.

Therefore, the present invention has been made to solve such problems in dead reckoning navigation, and provides a navigation device in which the current position and travel trajectory displayed on the display unit do not deviate from the road portion on the displayed map. With the goal.

Another object of the present invention is to provide a navigation device in which cumulative errors in direction and distance included in the estimated current position are automatically corrected.

[Means for solving problems]

The navigation device according to the present invention uses a steering angle sensor and a travel distance sensor, and also calculates the coordinates of a straight road whose minimum unit is between inflection points of the road, and the road angle of each straight road with respect to a predetermined reference direction. The collected information is stored as map information in a storage device, and for the straight road portion between the inflection points, the road angle and the travel distance of the road included in the map information read from the storage device are stored. By calculating the travel distance information supplied from the sensor, the current position on this straight road is estimated, and this estimated position is combined with map information and displayed on the display unit.

Further, in the navigation device according to the present invention, passage of an inflection point is detected from the integrated value of the rate of change of the steering angle obtained from the steering angle information, and the current position is corrected to the nearest inflection point. This is to correct the distance.

Furthermore, in the navigation device according to the present invention, a branching road is identified from the cumulative displacement of the steering angle when the estimated current position reaches an intersection in the map information, and from then on, this intersection is used as an inflection point. By calculating based on the road angle and mileage information of the specified road, the current position is sequentially estimated and displayed on the specified road.

[Effect]

In the navigation device configured in this way,
Information in which the coordinates of a straight road whose minimum unit is between inflection points of the road and the road angle of each straight road with respect to a predetermined reference direction are stored in a storage device as map information, and the information is collected from a mileage sensor. The current position is estimated by calculation based on the obtained mileage information from the inflection point and the road angle with respect to the road, and the current position determined by this estimation is combined with map information and displayed. Therefore, the determined current position is always located on the straight road section between the inflection points, and as in the past, the current position may be displayed on a section other than the road due to the cumulative error of the direction information. There will be no more things to do. In addition, since the current position is corrected to the inflection point when the inflection point is detected, the travel distance is corrected for each inflection point, and even when traveling a long distance, the cumulative error in the travel distance is reduced. arise and disappear. Furthermore, if the current position determined by the calculation is located at an intersection in the map information, the branch road to be traveled is specified based on the cumulative displacement of the steering angle, this intersection is set as an inflection point, and the specified intersection is Since the current position is calculated and displayed based on the road angle and travel distance information of the next road, the current position can be displayed accurately even on roads that intersect in a complicated manner. You can do it.

[Embodiments of the invention]

FIG. 1 is a block diagram showing one embodiment of a navigation device according to the present invention. In the figure, reference numeral 1 denotes a steering angle sensor mounted on a vehicle, which detects a steering angle that changes due to steering wheel operation and outputs steering angle information. A travel distance sensor 2 generates a travel pulse every time the vehicle travels a unit distance by detecting the rotation of a deflection shaft connected to, for example, a speedometer. Reference numeral 3 denotes a keyboard, which is used for specifying the display of a map including the starting point, setting various initial conditions, controlling operations, and the like. Reference numeral 4 denotes an external storage device constituted by, for example, a micro-floppy disk device or a CD read-only memory, which stores the coordinates of a straight line section between inflection points of the road, and the straight line based on a predetermined direction. Map information such as the angle of a portion is stored. In other words, Fig. 2 is a model of a straight road whose minimum unit is between inflection points A and C, and in this case, each road angle θ1 to θ8 from the horizontal position and the distance between each inflection point. Information in which D I''' D z is aggregated is combined with map information and stored.

5 is a media controller connected to the external storage device 4;
6 is a central processing unit configured by a microcomputer with a 16-bit configuration, and an input port P
A steering angle sensor 1, a mileage sensor 2, and a keyboard 3 are connected to +'=Pz, and the input/output capo) 1
0. A media controller 5 is connected to. 7 is an image memory connected to the input/output port ■0□ of the central processing bag W6. 8 is a graphic display connected to the human output port IOI of the central processing unit 6.
The controller has the function of displaying a combined map, the current position of the vehicle, and the travel trajectory on the display unit 9. 10 is the input/output port of the central processing unit 6■04
It is a Bach memory connected to.

The operation of the navigation device configured as described above will be explained below using the flowchart shown in FIG. First, a microfloppy, for example, as a storage medium storing map information is set in the external storage device 4, and the map information stored in the microfloppy is read out. The map information read out in this way is stored in the image memory 7 via the media controller 5 and the central processing unit 6. The map information stored in the image memory 7 is read out in accordance with instructions from the central processing unit 6 and then displayed on the display section 9 via the graphic display controller 8.

Next, while looking at the display map displayed on the display section 9, the driver uses the keyboard 3 to perform step S in FIG.
As shown in 1, the setting of the starting point, the direction of travel, and the start command are input.

Based on the positional information of the starting point input from the keyboard 3, the central processing unit 6 displays a mark indicating the current position on the map displayed on the display unit 9. next,
A case will be described in which a vehicle starts from, for example, an inflection point A shown in FIG. 2 and proceeds to inflection points B, C, and D. When the travel starts, the central processing unit 6 moves to the process shown in step S2, and calculates the road angle and travel distance of the straight road between the inflection points A and B included in the map information read from the external storage device 4. The current position is calculated by calculating based on the mileage information supplied from the sensor 2.

The current position determined in step S2 is then displayed on the display section 9 together with the map via the graphic display controller 8. Next, in step S3, it is determined whether the current position determined in step S2 has passed through an inflection point in the map information read from the external storage device 4. Here, since the vehicle has just started to depart, such step S
.

The determination in step S6 is negative and the process moves to step S6.

In step S, a change in the steering angle is determined from the steering angle information supplied from the steering angle sensor 2. but,
When the vehicle is traveling on a straight line between inflection points A and B, there is almost no change in the steering angle, so the determination in step Sh is NO and the process moves to step S8. In step S8, it is determined whether the current position matches an intersection in the map information. However, at this point, since it is just after departure, the step S,
The determination in step S2 is negative and the process moves to step S2.

When such an operation is repeated, the current position and the travel trajectory calculated by the calculation are displayed on the display unit 9 together with the map each time the vehicle passes through step S2.

The current position in this case is the inflection point A included in the map information read from the external storage device.

Since it is calculated by calculating the road angle of the straight road connecting between B and the driving distance information supplied from the driving distance sensor 2, the current position calculated by this calculation is always displayed on the display unit 9. It is located on a straight road connecting the inflection points A and B on the displayed map, and does not deviate from this road section.

Next, by repeatedly executing the step process described above, if the judgment in step S becomes YES, that is, even though the current position has not reached the inflection point B, the steering angle changes relatively significantly and the actual When it is determined that the travel has reached the inflection point B, the determination in step S becomes YES and the process moves to step S. In step S7, assuming that there is a distance error between the current position calculated by the calculation and the actual traveling position that has reached the inflection point B, the display position and distance are determined with the nearest inflection point B as the current position. After correcting, the process moves to step S2 via step S.

Next, when the current position calculated by the calculation reaches the inflection point B in the map information, the determination in step S3 becomes YES and the process moves to step S4. In step S4, a change in the steering angle is determined based on the steering angle information supplied from the steering angle sensor 1. Here, if the determination in step S4 is YES, it is determined that the current position calculated by the calculation and the actual traveling position that has reached the inflection point B match, and position correction is not necessary.
The process moves to step S2 via step S8. Also,
If the determination in step S4 is NO, the steering angle does not change even though the position display has reached the inflection point B, so the actual driving position has not reached the inflection point B. As a result, the process moves to step S. Step S,
In step S8, the current position determined by the calculation is corrected to the nearest inflection point (in this case, inflection point B), and the process moves to step S8. In other words, a positive error is accumulated in the mileage information, and the current position indicated by the calculation is assumed to have progressed earlier than the actual traveling position, and the inflection point that the current position indicated has passed first. Processing is performed to return the current position display to point B. By performing such processing, it becomes possible to hold the current position display at the inflection point B for a period of time until the actual travel position catches up with the inflection point and the actual travel position and the current position display match. .

In this manner, by executing the processes shown in steps 32 to S, all deviations in the current position display caused by cumulative errors included in the travel distance are corrected. Since this position correction is all processed between inflection points, the cumulative error of this distance is prevented from affecting the next inflection point, and the position is always accurate even when traveling long distances. Display will be possible.

Next, when the vehicle reaches the inflection point B, the central processing unit 6
changes the road angle θ1 to the road angle θ4 with respect to the straight road between the inflection points B and C included in the road information, resets the cumulative mileage, and starts again from this inflection point B. In this state, when the vehicle travels on the straight road between the inflection points B and C, the steps S2 to S described above,
By executing the process shown in , the current position is calculated, and the current position obtained by this calculation is displayed on the straight road between the inflection points B and C of the map displayed on the display unit 9.

When the current position obtained by performing such processing and calculating reaches an intersection (inflection point C in this case) located on the extension of this straight road included in the map information, that is, the reached inflection point If the point is an intersection, the process moves to step S to identify a branch road. In step S, the cumulative displacement amount of the steering angle is calculated based on the steering angle information supplied from the steering angle sensor 1, and from this displacement angle, a new branching road is selected, for example, a straight road between the inflection point C and D. Specify as. Then, the cumulative operation of the mileage information supplied from the mileage sensor 2 is reset once.

In this way, once preparations for traveling on the new branching road are completed, the process moves to step S2 and, as in the case described above, the inflection point C is set as the new branching road.
The road angle θ8 with respect to the straight road between -D is read from the map information, and this road angle θ8 and the mileage information are used as the inflection point C.
The current position is determined by calculation based on the distance information accumulated from , and is displayed on the display unit 9 together with the map information.

Therefore, by executing the process shown in steps S, S, even if the next inflection point reached is an intersection, a new branching road is automatically determined and the current location is Estimation calculations can be performed reliably.

〔Effect of the invention〕

As explained above, the navigation device according to the present invention uses a steering angle sensor and a travel distance sensor, and also uses coordinates of a straight road whose minimum unit is between inflection points of the road, and each direction relative to a predetermined reference direction. Information in which the road angles of straight roads are collected is stored as map information in a storage device, and in the straight road portion between the inflection points, the information on the road included in the map information read out from the storage device is stored in a storage device. The current position on this straight road is estimated by calculating based on the road angle and the mileage information supplied from the mileage sensor, and this estimated position is combined with map information and displayed on the display unit. It is.

For this reason, the current position determined by calculation is always on the straight road, so even if there is a cumulative error in the travel distance, the current position display may deviate from the road part on the displayed map and may be located in a field, etc. This will resolve the issue where it would appear inside.

Further, the navigation device according to the present invention detects passage of an inflection point portion from the integrated value of the rate of change of the steering angle obtained from the steering angle information, and corrects the current position to the nearest inflection point. This prevents erroneous display due to cumulative errors in mileage when the mileage increases. Furthermore, in the navigation device according to the present invention, a branching road is identified from the cumulative displacement of the steering angle when the estimated current position reaches an intersection in the map information, and from then on, this intersection is used as an inflection point. By calculating based on the road angle and travel distance information of the previously identified road, the current position is estimated and displayed sequentially on the identified road, so it is difficult to drive on complicated intersecting roads. Automatically identifies branching roads even when driving,
This allows accurate position display. Further, in the present invention, since a steering angle sensor such as a geomagnetic sensor which is not affected by disturbance is used, various excellent effects such as being able to display the current position with high precision are achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a navigation device according to the present invention, FIG. 2 is a diagram showing a model of a straight road whose minimum unit is between inflection points, and FIG. 3 explains the operation of FIG. 1. It is a flowchart figure for doing. 1--- Steering angle sensor, 2-- Mileage sensor, 3-- Keyboard, 4-- External storage device, 5-- Media controller, 6--1111 central processing unit, 7--- image memory,
8--Graphic display controller, 9--Display unit, 10--Buffer memory. Applicant NEC Home Electronics Figure 2 Figure 3 March 17, 1988 1, Display of case 1986 Patent rIJi312839 2 Name of invention Navigation device & Person making the amendment ↓ Date of amendment order α Contents of amendment

Claims (3)

[Claims] (1) A steering angle sensor mounted on a vehicle that detects changes in steering angle, a mileage sensor that detects vehicle travel, and coordinates of a straight road whose minimum unit is between inflection points of the road and predetermined coordinates. a storage device that stores information in which the road angles of each of the straight roads with respect to a reference direction determined as map information are stored as map information; a central processing unit that executes calculations to determine the current position based on the road angle of each of the straight roads as the minimum unit; and a central processing unit that combines the current position calculated by the central processing unit with the map information and displays it. A navigation device comprising: a display section. (2) A steering angle sensor mounted on the vehicle that detects changes in the steering angle, a mileage sensor that detects the running of the vehicle, and coordinates of a straight road whose minimum unit is between inflection points on the road and predetermined coordinates. a storage device that stores information in which the road angles of each straight road with respect to the reference direction determined as map information are stored as map information; a central processing unit that executes a calculation to calculate the current position based on the road angle of each straight road as a unit; and a central processing unit that combines the current position calculated by the central processing unit with the map information and displays it. the central processing unit detects passage of an inflection point portion from the integrated value of the rate of change of the steering angle obtained from the steering angle information, and displays the current position calculated by the calculation to display the latest change. A navigation device characterized by executing processing for correcting curve points. (3) A steering angle sensor mounted on the vehicle that detects changes in the steering angle, a mileage sensor that detects the running of the vehicle, and coordinates of a straight road whose minimum unit is between inflection points of the road and predetermined coordinates. a storage device that stores information in which the road angles of each straight road with respect to the reference direction determined as map information are stored as map information; a central processing unit that executes a calculation to calculate the current position based on the road angle of each of the straight roads as a unit; and a central processing unit that combines the current position calculated by the central processing unit with the map information and displays it. and a display unit, when the current position determined by the calculation reaches an intersection in the map information, the central processing unit identifies the branching road on which the vehicle is traveling based on the cumulative displacement of the steering angle obtained from the steering angle information. and thereafter, extracts the road angle with respect to the specified branch road from the map information to calculate the current position.