JPS6355005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a travel information display device that displays the travel trajectory of a vehicle such as an automobile on a display.

This type of conventional device uses a travel distance detector such as an electromagnetic pickup and a travel direction detector using a magnetic sensor to convert the travel distance and travel direction into electrical signals, and a control circuit using a microcomputer etc. There are devices that process and calculate these electrical signals and display the driving trajectory and current position on a display device such as a CRT. It is possible to know whether the vehicle has traveled along the road or its current driving position by referring to the map. Conventionally, in this type of device, the travel trajectory can be calculated and displayed from the signals obtained from the travel distance detector and the direction detector as described above, but the correspondence between the travel trajectory and the roads on the map is difficult to understand. This required a method such as overlaying a map sheet with a map drawn on a transparent sheet on the display. As a device that does not have such drawbacks, a method has been proposed in which the map itself is displayed on a display and the driving trajectory is displayed over the displayed map, but the storage device for storing the map information is enormous. It is said that this is difficult to realize. In addition, in the case of the above-mentioned method of overlapping map sheets, if there is an error in the mileage detector or direction detector, the travel trajectory and the road on the map will not match, and corrections will be required, which is inconvenient in practical terms. It is. The above problem can occur even when a map is displayed on a display.

The present invention has been made in view of the above points, and makes it possible to display a map and a travel trajectory on a display in an overlapping manner without increasing the size of the device configuration, and also to prevent errors in various detectors. It is an object of the present invention to provide a driving information display device capable of displaying a driving trajectory without deviating from the road on a map even if there is a road. Hereinafter, a detailed explanation will be given according to an example.

FIG. 1 is a connection diagram showing an embodiment of the present invention, in which 1 is a connection diagram showing an embodiment of the present invention.
A mileage detector that generates a signal with a frequency proportional to the traveling speed, 2 a direction detector for measuring the direction of travel of the vehicle, 3 a map memory that stores information such as roads on the map, and 4 a A traveling trajectory display device (hereinafter abbreviated as a display device) for displaying the map information and traveling trajectory provided by the map memory 3, 5
reads data from map memory 3 and displays it on display 4.
6 is a control circuit for displaying a map on the display 4, calculating the travel trajectory, and displaying it on the display 4;
10 is a switch for instructing the control circuit 5 to select a control mode. be. As the direction detector, a method of measuring the direction of earth's magnetism, a method of using a gyro, etc. can be considered, but the following explanation will be about a method of measuring the direction of earth's magnetism. However, even if other methods such as a gyro are used, the principle of calculating the running trajectory is almost the same. As the direction detector 2, a magnetic sensor having two orthogonal detection axes is used. As shown in FIG. The direction detector 2 is installed at an arbitrary position on the vehicle 7 so as to be placed in a horizontal plane perpendicular to the direction of travel. Consider a case where the vehicle is placed so that the direction of travel of the vehicle forms an angle θ with magnetic north. In this case, when the magnitude of the horizontal component of geomagnetism is H, the magnetic field components H _U and H _V in the two detection axis directions of the direction detector 2 are H _U =K ₁ Hcosθ,
It is given by H _V = K ₂ H sin θ. Here, K ₁ and K ₂ are constants determined by the structure of the vehicle, and K ₁ and K ₂ are approximately equal. In the following explanation, K ₁ =K ₂ =K' is assumed for simplicity, but generality is not lost by this. When the aforementioned magnetic field is applied to the orientation detector 2, the two electrical output signals EU _{and EV} obtained from the orientation detector 2 are as follows: EU = _{AH U =} AK'Hcosθ, _EV =
It is given by AK′Hsinθ. Here, A is a constant related to the sensitivity of the direction detector 2. In the above formula
If we replace AK′=K, E _U =KHcosθ, E _V =
It becomes KHsinθ. As shown in FIG. 2, coordinate axes X and Y are determined so that the Y axis corresponds to north and the X axis corresponds to east. In the state shown in FIG. 2, when the vehicle 7 moves by a small distance d in the direction of travel, if the amounts of movement in the X direction and Y direction are respectively Δx and Δy, then Δx and Δy
is given by the following equation.

Δx=dsinθ, Δy=dcosθ…(1) Also, E _U =KHcosθ, E _V =KHsinθ to cosθ=
Since E _U /K _H , sinθ=E _V /K _H , and E _U ² + E _V ² = K ² H ² , cosθ=E _U /√ _U ² + _V ² , sinθ=E _V /√ _U ²
+E _V ² , and from equation (1) Δx=d・E _V /√ _U ² + _V ² , Δy=d・E _U /√
_U ² + _V ² …(2). Therefore, the position (x, y) when the vehicle 7 moves while changing direction is given by the following equation.

Here, ∫dl is the integral with respect to the direction of travel of the vehicle.

When performing integration using a digital computer, etc., integration is used instead, so equation (3) can be expressed as
When expressed as an integration for each movement, it becomes as shown in equation (4).

Therefore, the current position 0 (x, y) after traveling from an arbitrary point p is x at point p.
=y=0, and each time the rear vehicle moves a small distance d, d・E _V /√ _U ² + _V ² in x and y, respectively.
The traveling trajectory is obtained by adding d·E _U /√ _U ² + _V ² and connects the points given by (x, y) from point P to point Q.

As mentioned above, the mileage detector 11 generates a signal having a frequency proportional to the moving speed of the vehicle, but when this signal is converted into a pulse, one pulse is generated every time the vehicle travels a certain distance d. That will happen. Therefore, each time a pulse is obtained from the mileage detector 1, d・
It is easily understood that if the control circuit 5 performs the process of adding E _V /√ _U ² + _V ² and d·E _U /√ _U ² + _V ² , the travel trajectory and current position can be calculated.

Next, the map memory 3 will be explained. FIG. 3 shows an example of a road map consisting of three main roads a, b, and c, but no matter how advanced semiconductor technology is, it is impractical to store all roads in the map memory 3. If the map is limited to main roads only, it is possible to store a map as shown in Figure 3 as a two-dimensional figure.Furthermore, by approximating roads as a straight line as shown in Figure 4, the amount of data can be greatly reduced. This is even more advantageous in practical use. Various data formats can be considered when storing map information in the map memory 3, but for example,
As shown in the figure, if the road is approximated by a broken line, road a
Store the coordinates (x _{1 ,} y ₁ ), (x ₂ , y ₂ )...(x ₅ , y _{5 ) of A 1 , A 2 , A 3 , A 4 , A 5 as appropriate binary numbers} in the map memory as data. 3 should be memorized. If the broken line approximation is not used as shown in FIG. 3, each road may be divided into appropriate sections, and the coordinates of both ends of each section may be stored in the map memory 3 in the same manner as described above.

Next, the marker moving device 6 will be explained. Fourth
In the figure, ◎ indicated by M is an example of a current position marker, and the center point of the circle represents the current position. When the map data is read from the map memory 3 and the map is displayed on the display 4, the current position marker M appears at approximately the center of the screen of the display 4. Before moving the vehicle 7, it is necessary to move the current position marker M to the current position on the map. The marker moving device 6 is used for this purpose. FIG. 5 shows a specific example of the marker moving device 6, in which switches 61, 62, 63, and 64 move the current position marker M to the right, left, and right on the screen of the display 4, respectively.
It is used to move the current position marker M up and down.

For example, in FIG. 4, if the starting point is point _B2 on road b, operate the switch 62 to move the current position marker M to M', then operate the switch 64 to move the current position marker to M'. By matching B ₂ , preparations for calculating and displaying the travel trajectory using the B ₂ point as the origin are completed.

In FIG. 1, a switch 10 can instruct the control circuit 5 to select two control modes: M mode (first mode) and L mode (second mode).
The M mode is a highway driving mode and is used when driving on roads stored in the map memory 3 and displayed on the display 4 as shown in FIG. 3 or 4. The L mode is a side road driving mode and is used when driving on a road that is not stored in the map memory 3, that is, a road other than a main road. Using FIG. 4 as an example, the operation in M mode will first be described.

When starting from point _B2 in FIG. 4, the current position marker M is made to coincide with point _B2 according to the procedure described above. From B ₂ on road b via B ₃ to B ₄
If the vehicle travels up to the point B ₂ ' (Figure 3) on the actual map, which corresponds to point B ₂ , the vehicle is facing almost east, so if normal calculations are performed, it will be at one point in Figure 4. The travel trajectory will be as shown by the chain line b', which will not match the road displayed on the display 4, but the control circuit 5 will determine the line segment closest to the actual direction of travel of the vehicle ( _{east at point B2 )} at point B2. Select B ₂ − _{B 3} as the road on which the vehicle will travel from now on, and the vehicle will depart from B ₂ and travel to B _3.
While the vehicle is traveling toward , the distance traveled is calculated from the signal obtained from the distance detector 1, and the travel trajectory is displayed on the line segment _B2 - _B3 . In this case, the signal from the azimuth detector 2 is mainly used for selecting a road at a branch point or checking the calculation results, and does not need to be actively used for calculating the travel trajectory. The vehicle _moves on the line segment B ₂ − B ₃
If we move in the direction of , reach point E, turn left at point E and head toward C ₅ on line segment C ₆ - C ₅ , as can be seen from Fig. 3, the output of direction detector 2 is The control circuit 5 now points to the line segment E-C ₅ (or
C ₆ −C ₅ ) is selected as the road on which the travel trajectory is to be displayed next, and the same calculation and display operations as described above are performed. As the vehicle advances northeast from point E on road C, the current position of the vehicle calculated by control circuit 5 and displayed on display 4 moves in the direction of _{C5 on line segment E-C5 ,} and C Reach ₅ . Line segment C ₅ at point C ₅
If the vehicle continues to travel on the main road C indicated by _-C4 , the control circuit 5 only needs to calculate the current position of the vehicle along the line segment _C5 - _C4 according to the procedure described above. , if the road is changed to road h, which is not a main road (therefore not displayed on display 4) at point _C5 , it is clear that the current position of the vehicle cannot be calculated correctly using the above procedure. be. When driving on a road other than a main road, the above problem can be solved by switching the switch 10 at point _C5 and instructing the control circuit 5 to perform calculations in the L mode, that is, the side road driving mode. i.e. point C ₅
When the control circuit 5 is instructed to calculate in L mode, the control circuit 5 ignores the map information stored in the map memory 3 and uses the signals obtained from the mileage detector 1 and the direction detector 2 as variables. The current position (or travel trajectory) of the vehicle is calculated and displayed on the display 4.
to be displayed. When such a calculation is performed, the signals obtained from the mileage detector 1 and the direction detector 2 contain some errors, so the current position of the vehicle displayed on the display 4 is shown virtually in Fig. 4. Although it does not necessarily match the road h shown, the distance traveled by driving on a side road is generally shorter than that traveling on a main road, so the influence of the above error is relatively small. If the vehicle travels on a road h that is not a main road and switches the switch 10 to M mode again when the vehicle actually arrives at point _A3 , the current position of the vehicle displayed on the display 4 just before switching is confirmed to be accurate. Even if the current position of the vehicle calculated in L mode is not the same as _A3 , by switching the switch 10 to M mode, the closest point on the highway that has the current position of the vehicle calculated in L mode, i.e.
The correction to A ₃ can be easily performed by the control circuit 5. By appropriately switching the switch 10 in this way, no matter what road the vehicle travels on,
The current position or travel trajectory of the vehicle can always be calculated and displayed with sufficient accuracy for practical use.

The above explanation mainly concerned the case where roads are approximated by broken lines and stored in the map memory 3.
Exactly the same thing can be done even if the map information is stored in the map memory 3 as a curve as shown in FIG.

Furthermore, in this embodiment, as shown in FIG. 5, the marker moving device 5 is constructed so that the current mark M on the display 4 can be moved vertically and horizontally using four switches 61 to 64. For example, it is also possible to enter predetermined coordinates on the screen of the display 4 using a numeric keyboard switch that allows arbitrary numerical values to be set, and then immediately move the current position mark M to the desired coordinates. It is.

As described above, in the present invention, a control circuit reads out map information from a map memory that mainly stores information such as main roads, displays this on a display, and instructs the control circuit to perform two different calculation display modes. When the first mode, M mode, is selected with this switch, the calculation of the current position and driving trajectory is corrected so that the current position mark does not deviate from the road displayed on the display. When the second mode, L mode, is selected, the current position and travel trajectory are determined based only on the signals from the mileage detector and direction detector, regardless of the road displayed on the display. Since the calculations are performed and the results are displayed, it is possible to select a calculation display mode suitable for the place and type of driving, and a highly practical device can be realized.

[Brief explanation of the drawing]

Fig. 1 and Fig. 5 are connection diagrams showing an embodiment of the present invention, Fig. 2 is a drawing for explaining the principle of running trajectory calculation, Fig. 3 is a drawing showing an example of a map, and Fig. 4 is a straight line. FIG. 2 is a diagram showing an example of a converted map. In the figure, 1 is a travel distance detector, 2 is a direction detector, 3 is a map memory, 4 is a travel device, 5 is a control circuit, 6 is a current position marker moving device, and 10 is a travel mode instruction switch. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A mileage detector that detects the mileage of the vehicle, a direction detector that detects the direction of travel of the vehicle, and an indicator that displays the travel trajectory or current position of the vehicle.
Based on a map memory storing map information, a marker moving device for moving a current position marker for indicating the current position of the vehicle displayed on the display, and map data read from the map memory,
In addition to displaying a map on the display, the signals obtained from the mileage detector and direction detector are processed, and the current position or It is equipped with a control circuit that calculates a travel trajectory and displays the travel trajectory or current position superimposed on the map displayed on the display, and a changeover switch that instructs the control circuit to select two different calculation display modes. In the first mode instructed by this changeover switch, the control circuit causes the control circuit to display on the display based on the signals obtained from the mileage detector and the direction detector and the data obtained from the map memory. In the second mode instructed by the changeover switch, the control circuit corrects calculations of the vehicle's current position or travel trajectory so that the vehicle's current position does not deviate from the road, and displays these on the display. Calculating the current position or travel trajectory of the vehicle based only on signals obtained from the mileage detector and the direction detector, regardless of the road displayed on the display, and displaying these on the display. A driving information display device featuring: