JP2964832B2 - Road map display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a road map display device, and more particularly, to a road map display device capable of displaying a road map in the direction of travel of a vehicle.

[0002]

2. Description of the Related Art Conventionally, in order to assist a vehicle in reaching a destination, a navigation device that displays the current position information of the vehicle to a driver or a passenger (hereinafter, simply referred to as a “driver”) of the vehicle is provided on the vehicle. May be installed. This navigation device has a small computer and a display device, and can detect a traveling distance and a traveling direction by a vehicle speed sensor and an azimuth sensor, respectively, obtain a current position of the vehicle, and display the current position of the vehicle together with a road map on the display device. It is.

Further, according to the setting of the destination by the driver, link data for route calculation in a range including the departure place (current location) and the destination is read out from the memory, and based on the link data, the link is changed from the departure place to the destination. There is also known an optimum route calculation method for calculating an optimum route to be reached (Japanese Patent Laid-Open No. Hei 2-2772)
No. 00). The optimum route calculated in this way is displayed over the road when the road map is displayed on the display device.

[0004]

By the way, in the conventional road map display, the current position of the vehicle is set to be always at the center of the display screen. For this reason, about half of the display screen is already filled with information on roads that have already passed, and in order to display valid information (information on the direction of travel),
Only about half the space of the screen can be used.

[0005] The size of the display screen of the navigation device is limited due to its characteristics of being mounted on a vehicle, and it is important to display as much effective information as possible within the limited size. Accordingly, an object of the present invention is to provide a road map display device capable of displaying effective information over a wide range as much as possible within a limited screen.

[0006]

[0007]

In the road map display device of the means and functions for solving the problem] 請 Motomeko 1, this route calculation by searching the route calculation link data range including the departure point and the destination from the route calculation link memory Calculating the optimal route between the departure point and the destination based on the link data for the vehicle, and displaying the position of the vehicle and the link row constituting the calculated optimal route on a road map in a predetermined range. Selecting, from among the nodes (called nodes) of the link train constituting the optimum route that the vehicle is about to travel, the node that is most frequently included in a displayable fixed-size image area including the current position of the vehicle, The minimum rectangular area including the selected node and the current position of the vehicle is determined as described above, and this rectangular area and the longest part of the route to the first nodal point deviating from the fixed-size image area are determined. As rectangular display, and it determines the display area is for displaying.

According to the present invention, the current position of the vehicle and the longest portion of the optimal route on which the vehicle will travel are displayed on the screen of a fixed size.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 2 is a block diagram showing a configuration of the navigation device according to one embodiment of the present invention. This navigation device is mounted on a vehicle and used to support traveling in the vehicle. This device includes a direction sensor 1 for detecting a direction, a distance sensor 2 for detecting a traveling distance of the vehicle, and a shift sensor 3 for detecting whether the vehicle is moving forward or backward. Have been. These three sensors 1,
The detection outputs 2 and 3 are given to a position detecting device 4 which is a position detecting means.

The position detecting device 4 is for calculating the current position of the vehicle. The position detecting device 4 obtains the azimuth detected by the azimuth sensor 1 and is given from the shift sensor 3 to the distance detected by the distance sensor 2. Taking into account the forward or backward movement of the vehicle,
Find the travel distance of the vehicle. Therefore, for example, if the accurate initial position data of the vehicle is given to the position detection device 4 before the vehicle starts moving, the position detection device 4 calculates the current position of the vehicle thereafter.

Further, the position detecting device 4 calculates travel locus data based on the current position data of the vehicle, and compares the travel locus data with the position calculation road map data (described later) stored in the disk D2. Based on a so-called road map matching method, a function of detecting a road and a vehicle position on the road in consideration of the existence probability of the vehicle is provided. A beacon receiver may be further connected to the position detection device 4. The beacon receiver is for receiving data such as position information and road information (intersection name, destination guidance, traffic congestion information, accident information) radiated from a beacon antenna installed on the road side of a road or the like. The road information received by the beacon receiver is given to the display control device 5,
Finally, it is displayed on the display device 7.

Further, a GPS receiver may be connected to the position detecting device 4 as an optional device. If a GPS receiver is provided, a signal from a GPS satellite can be received to accurately detect the absolute azimuth or directly detect the current position of the moving object. During the above-described position detection operation, if the data of the exact position of the vehicle is input by the beacon receiver and the GPS receiver, the position detected by the position detection device 4 is forcibly reset.

Data representing the current position of the vehicle calculated by the road map matching method or the like is provided to a display control device 5 which is a control center of the navigation device.
The display control device 5 includes a CPU, a ROM, a RAM, and the like.
A display device 7 such as an RT and a CD-drive 8 are connected.

The display control device 5 performs a CD-ROM based on the current position data of the vehicle calculated by the position detection device 4 and the like.
The drive 8 is controlled. The CD-drive 8 reads display road map data including the current position of the vehicle from the disk D1 loaded in advance and outputs the read road map data to the display control device 5 in response to a control signal given from the display control device 5. The road map data for display is created from a 1/2500 road map database, and includes road map data including roads, place names, famous facilities, railways, rivers, and the like. The display control device 5 gives the current position data calculated by the position detection device 4 and the display road map data to the display device 7 to generate a road map and a vehicle current position mark on the road map, Display.

The CD-drive 8 reads path calculation link data for path calculation from the disk D3 loaded in advance in response to a control signal given from the display control apparatus 5, and displays the read control apparatus. Output to 5 The display control device 5 calculates an optimal route from the current position to the destination, obtains coordinates on a road map, and displays the optimal route.

Here, the link data for route calculation includes a road map (a highway national road, an exclusive motorway, a national road, a prefectural road, a city road of a designated city, and other living roads. Is referred to as a "highway", and the other roads are referred to as "general roads.") Is data that is formed by combining nodes and links in mesh units. Due to the characteristics of the road map database, a closed network is formed nationwide for roads higher than national roads among the main roads.

Here, a node is generally a coordinate point for specifying a road intersection, a road bending point, a mesh boundary, a dead end point, and the like. What connects each node is a link. Link data is a link number,
The address of the start node and end node of the link, the distance of the link, the direction passing through the link, the required time in that direction, the type or type of road (general road link or highway link), road width, one-way traffic, and no right-turn , Left turn prohibition, and toll road data.

The mesh is, for example, a Japanese road map divided by a longitude difference of 1.degree.
The primary mesh set as km x about 80 km and this 1
The secondary mesh is divided into eight equal parts in the vertical and horizontal directions, and the secondary mesh is set to have a vertical and horizontal distance of about 10 km × about 10 km. However, the vertical and horizontal distances and the aspect ratio are not necessarily limited to this configuration.

The above-described road map data for position calculation is created from a 1 / 25th road map database, and is more detailed and precise data than the road map data for route calculation. This is a one-layer structure data including some link information (road width and the like). The number of types of link information is small because it does not include required time data or traffic regulation data that is not directly needed for position detection (however, road width may be useful for position detection as well. Is).

Thus, the road map data for position calculation,
The reason for separating the link data from the route calculation link data is that the former requires detailed accuracy for road map matching, and the latter needs to attach various data necessary for route calculation rather than accuracy. The display control device 5 is configured by the hardware shown in FIG. That is, the display control device 5
Are the discs D1, D2, D through the CD-drive 8.
3, a memory drive control unit 51 for obtaining necessary data from
An image memory controller 52 functioning as a read control unit for displaying an image of a necessary area on the display device 7; an input processing unit 5 for processing input information set by a touch switch
3. Image memory 5 for registering display road map data
4, a vehicle position recognition unit 55 that takes in the vehicle position calculated by the position detection device 4 as data, a CPU 56 that functions as a display area determination unit, and a main memory 57 that temporarily stores the optimum route information calculated by the optimum route calculation device 9. Have.

The optimum route calculation device 9 has a function of calculating the optimum route from the current position to the destination by the Dijkstra method or the like. This Dijkstra method assumes a node or link closest to the destination as a start point, a node or link closest to the departure point as an end point, assumes a tree of links from the start point to the end point, and links all paths constituting the tree. In this method, the costs are sequentially added, and only the route with the lowest link cost that reaches the departure point is selected. Here, items to be considered when estimating the link cost include mileage, travel time, use of highway, right / left turn count, highway running probability, avoidance of accident-prone areas, and other settings according to the driver's preference. There is a matter. - first display procedure - The following is a description of the road map display procedure of the display control unit 5, first, regardless <br/> hand turn with be described for displaying a roadmap to the optimal path.

During traveling, the CPU 56
5, the speed V of the vehicle is obtained, and the input processing unit 53 obtains the scale S of the road map to be displayed. Then, based on the speed V and the scale S,
The moving amount W of the display area along the traveling direction of the vehicle is obtained.
The moving amount W increases as the speed V increases and the scale S increases (the number of the denominator of the fraction decreases), and the speed V decreases and the scale S decreases.
Is smaller (the denominator of the fraction is larger).

FIG. 4 shows a graph for calculating the movement amount W used by the CPU 56, where the product V · S is on the horizontal axis and the movement amount W is on the vertical axis. Product VS is upper limit W
_As long as it is less than ₀ , the movement amount W increases linearly with the product VS. For this reason, the faster the vehicle travels, the more the road map located further in the traveling direction is displayed.

FIG. 5 shows a road map of a region where the vehicle travels, and the vehicle is indicated by a triangular mark. The movement amount W shown in FIG. 5 is obtained from the graph of FIG. Conventionally, as shown in FIG. 6, a road map is displayed centering on a vehicle, so that the destination of the vehicle is displayed only in the upper right half of the road map.

However, according to the present invention, as shown in FIG. 1, a road map is displayed centering on a point at a distance W in the direction of travel of the vehicle, so that the destination of the vehicle is displayed as the whole road map. You. Therefore, the display area including the current position of the vehicle and the display area centered on a point a predetermined distance away from the current position of the vehicle can be determined and displayed, so that effective information (information on the traveling direction) can be displayed on almost the entire screen. Will be displayed.

As can be seen from the graph of FIG. 4, when the product V · S exceeds a certain value, the movement amount W is prevented from increasing any more. The upper limit value W0 is set to be substantially equal to the length V / 2 (see FIG. 9) of a perpendicular line extending from the center of the display screen to the long side. Therefore,
No matter how fast you drive, the position of the vehicle will always be displayed on the screen. --- Second Display Procedure-- Next, an optimal route display procedure (corresponding to claim 1 ) for displaying an optimal route as long as possible under the condition that the scale of the map is constant will be described.

First, a route calculation procedure, which is a stage before displaying a route, will be described. The CPU 56 displays a menu screen (not shown), and allows the driver to select items such as the magnification of the road map and the selection criterion of the optimum route using the touch switch 6. When this operation is completed, a road map including the current position of the vehicle is displayed on the screen. The driver searches the destination by scrolling the road map and touches the destination position. When the destination is touched, the CPU 56 obtains the destination information from the input processing unit 53, and
5 obtains current location information based on a vehicle position signal from the position detection device 4.

The CPU 56 sends information on the current position and the destination to the optimum route calculation device 9 and
Calculates the optimal route from the current position to the destination by using a calculation method according to the selection criterion set on the initial screen. The CPU 56 stores the determined optimum route information, that is, the link string constituting the optimum route in the main memory 57.
In this manner, the link sequence forming the optimum route is determined. In this embodiment, attention is paid to the nodes which are the nodes connecting the links in the link sequence.

The current position of the vehicle is D ₀ (for convenience, D ₀ is also referred to as a node), the node closest to D ₀ on the optimal route in the traveling direction is D ₁ , the next node is D ₂ , and the next node is D ₂ . Are D ₃ ,... The CPU 56 determines the position on the road map of the display screen, that is, the display area, so that the display screen includes the node D ₀ and includes as many nodes as possible on the optimal route. I do.

FIG. 7 is a flowchart showing a procedure for determining a display area. First, a counter n is set to 0 (step S1). Then, it is examined whether or not there is a display area that simultaneously includes the nodes D ₀ ,..., D _n (step S2). Since n = 0 at the beginning, the node D ₀
Is always present. Therefore, the process proceeds to step S3. In step S3, it is determined whether or not the node D _n is a destination node. If it is not the destination node, n is incremented by 1 (step S4), and the process returns to step S2. If it is a destination node, the center of the smallest rectangular area including the nodes D ₀ ,..., D _n is displayed as the center of the display area (step S7).

In step S2, nodes D ₀ ,.
, D _n are examined to determine whether or not there is a display area.
_From among the display areas including ₀ ,..., D _n−1 , the one that can display the longest route is searched for. For that, node D
Assuming a minimum rectangular area including ₀ ,..., D _n−1 , an area that includes this minimum rectangular area and that can display the longest part of the optimal route is searched for.

As a specific example, consider a link string L forming an optimum route as shown in FIG. 8, and consider nodes D ₀ , D ₁ , D ₂
Is present at the same time, but there is no display area at the same time that the nodes D ₀ , D ₁ , D ₂ , and D ₃ are simultaneously included. Nodes D ₀ and D in this case
_1, consider the minimum rectangular region ABCD including a D _2. Then, the vertices of the rectangle ABCD A, B, C, longest vertex distance between D and node D ₃ (in this case A (= D ₀₎₎ to select the (step S5).

Next, as shown in FIG. 9, the size of the angle formed by the diagonal and the horizontal side of the display screen is α. Then, the angle is the line segment AD ₃ and transverse side and theta, performs the following determination. When α ≦ θ <180-α or 180 + α ≦ θ <360- α, the perpendicular line erected from a point P on the horizontal line passing through the point A is a point that crosses the line segment AD ₃ is M, the length of the line segment PM Is determined such that is half the vertical size V of the display area (see FIG. 10). This point M is set as the center of the display area (step S6).

Next, when 0 ≦ θ <α or 180−α ≦ θ <180 + α or 360−α ≦ θ <360, the length from the point A becomes half the horizontal size H of the display area. Find one point P on the horizontal line. When a perpendicular erected from the P and M points across the line segment AD ₃ (see FIG. 11), the center of the point M display area (step S
6).

The display area centered on the M these points are the minimum rectangle comprises ABCD, and contains the longest an optimal path L ₂₃ connected to the node D ₃ that do not appear on the display screen (see FIGS. 12 and 13) . Therefore, find the center point M of the display area in the manner described above, if a road map display around the point, when displaying in a conventional manner around the current position D ₀ of the vehicle (see FIG. 14) and compared to, together including the current position D ₀ of the vehicle, it is possible to display the region containing the longest optimum route to be from now.

[0036]

[0037]

According to the first aspect of the present invention, when displaying the optimal route, the current position of the vehicle and the longest portion of the optimal route on which the vehicle will travel can be displayed in a screen of a fixed size. Therefore, the limited screen can be effectively used. In addition, the driver can know the state of the road on the optimal route at an early stage, and can perform safer driving.

[Brief description of the drawings]

FIG. 1 is a road map displayed in accordance with the present invention.

FIG. 2 is a schematic block diagram of a navigation device including a road map display device that performs a road map display of the present invention.

FIG. 3 is a functional block diagram illustrating details of a display control device.

FIG. 4 is a graph for obtaining a movement amount W for determining a center of a road map display.

FIG. 5 is a diagram showing a road map of an area where a vehicle travels.

FIG. 6 is a conventional road map display diagram in which the destination of a vehicle is displayed only in the upper right half of the road map.

FIG. 7 is a flowchart illustrating a procedure for determining an optimum route display area.

FIG. 8 is a diagram showing a link string L forming an optimum route.

FIG. 9 is a diagram showing a shape of a display screen.

FIG. 10 is a diagram illustrating a method of obtaining a center of a display area.

FIG. 11 is a diagram illustrating a method for obtaining a center of a display area.

FIG. 12 is a diagram showing a relationship between a link row L forming an optimum route and a display area.

FIG. 13 is a road map displaying an optimal route according to the present invention.

FIG. 14 is a conventional road map display diagram in which the optimum route in the traveling direction is displayed only in the upper right half of the road map.

[Explanation of symbols]

4 position detecting device 5 display controller 9 optimal path calculation device 52 the image memory controller 54 the image memory 56 CPU ABCD minimum rectangular region D _1, D _2, D ₃ disc

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01C 21/00 G08G 1/0969 G09B 29/10

Claims (1)

(57) [Claims] 1. A road map memory for storing road map data, a position detecting means for detecting a position of a vehicle, and a departure point and a destination are determined from a link memory for route calculation in accordance with setting of a destination by a driver. An optimal route calculation means for searching for route calculation link data in a range including the route and calculating an optimal route between the departure point and the destination based on the route calculation link data; Display control means for displaying a position and a link sequence constituting an optimum route calculated by the optimum route calculation means on a road map of a predetermined scale, wherein the display control means temporarily stores image data. An image memory to be stored, a display area determining unit that determines an image area of a certain size that can be displayed, and reading image data of the area determined by the display area determining unit from the image memory. And a display control unit, wherein the display area determination unit includes the largest number of nodes in the fixed-size image area including the current position of the vehicle among the nodes of the link train that constitute the optimal route that the vehicle is to travel. Is determined, and the minimum rectangular area including the nodal point selected as described above and the current position of the vehicle is determined.This rectangular area and the first nodal point deviating from the image area of the fixed size are determined. A road map display device for determining a display area so that the longest part of the route is displayed.