JP2006317322A - Navigation device and program for navigation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the quantity of road data to be recorded in an external DRAM, in a navigation device for a vehicle for acquiring the road data of a mesh where a guide route passes from DVD-ROM or the like and recording the data in the external DRAM. <P>SOLUTION: When a temporary guide route to a destination enters the second adjacent mesh from the first mesh of map data and has a return part route entering the first mesh from the second mesh without passing another mesh (130, 150), the navigation device for the vehicle replaces the return part route with an alternate part route passing only the first mesh (140, 160), and selects the resultant route as the guide route (170). The device records in the external DRAM only a mesh where the guide route passes between a wide-area mesh, a medium-area mesh and a detailed mesh partitioned in each hierarchy of the map data having a hierarchical structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a navigation device that acquires road data in units of areas based on a geographical division and displays a road map on a display device based on the acquired road data, and a program for the navigation device.

  2. Description of the Related Art Conventionally, there has been a navigation device that acquires road data in units of areas (hereinafter referred to as meshes) based on geographic sections, records the data in a storage medium such as a RAM, and displays a road map on a display device based on the recorded road data. Widely used.

  In such a navigation device, when a guidance route to the destination is determined due to a request to reduce the amount of data stored in the storage medium, only a mesh including the guidance route is recorded in the storage medium. There are things that are supposed to do.

  An example of a navigation device that performs such an operation is a navigation device having a corridor function. The corridor function is a mesh that allows a guide route to pass from a road data storage medium mounted on a removable storage medium reader (eg, DVD drive, CD drive) of the navigation device to a DRAM or the like in the navigation device in advance. This is a function for copying road data and causing the display device to display a road map using the copied road data. By using such a corridor function, even when a storage medium (for example, a music CD or a movie DVD-ROM) other than a road data storage medium is inserted into the reading device and the navigation device is reproducing music, the navigation device By using the copied data, the road map display along the guidance route can be continued.

  In such a navigation device that acquires mesh road data passing through a guide route and records it on a storage medium, the amount of road data to be recorded increases significantly due to a slight difference in the shape of the guide route. There is. For example, let us consider a case where a guide route 73 from the current position 71 to the destination 72 is determined in an area as shown in FIG. In such a case, since the guidance route 73 passes through all of the meshes 81 to 84, the navigation device records all the map data of these meshes in the storage medium. However, since the guide path 73 passes only a very small part of the mesh 84, the navigation device can be changed by slightly changing the part corresponding to the mesh 84 of the guide path 73 so as to fit in the mesh 82. Eliminates the need to acquire road data of the mesh 84.

  Further, in a navigation device that acquires road data in units of meshes, records the data in a storage medium, and displays a road map on a display device based on the recorded road data, the road data used has a hierarchical structure. There is something. The road data having a hierarchical structure has data of a plurality of hierarchies, and the data of each hierarchy has data of links and nodes in the area covered by the data. However, the areas covered by the data of the respective layers are overlapped, and the data of the links and nodes included in the data of the respective layers in the overlapping areas do not match. For example, for a certain area, a link and a node included in data of a certain hierarchy are obtained by thinning a part (for example, a narrow street link) from a link and a node included in data of a hierarchy lower than that hierarchy. Also good. Further, the size of the mesh in each layer may be wider in the upper layer.

  FIG. 13 conceptually shows an example of hierarchical road data. In the figure, the largest rectangle at the top represents the wide area mesh for the top hierarchy, and each of the plurality of rectangles at the bottom represents the detailed mesh for the bottom hierarchy, Each of a plurality of rectangles between the uppermost part and the lowermost part represents an intermediate mesh for the middle hierarchy. A plurality of middle meshes cover an area covered by one wide area mesh, and a plurality of detailed meshes cover an area covered by one middle area mesh. Further, the road data for the lowest hierarchy, that is, the detailed road data includes all links and nodes in the region including the narrow streets, and the road data for the middle hierarchy, that is, the middle area road data, is the detailed road. The road data for the highest hierarchy, including links and nodes excluding narrow streets from the data, that is, wide-area road data, is the link only for major roads such as national roads and expressways, excluding prefectural roads from the middle-area road data. And nodes.

  In such a navigation device in which hierarchical road data is acquired in units of meshes and recorded on a storage medium and a road map is displayed on a display device based on the recorded road data, conventionally, road data is more than necessary. It may be acquired and stored. For example, when hierarchical road data is used in the navigation device having the above-described corridor function, conventionally, when road data of a certain wide area mesh is recorded in a storage medium, the mesh of the lower hierarchy in which the wide area mesh and the cover area overlap with each other. All the road data was recorded on a storage medium.

  For example, as shown in FIG. 14, consider a case where a guide route 93 from the current position 91 to the destination 92 is determined in the same area as FIG. 12. In such a case, since the guiding path 93 passes through the wide area meshes 82 to 84, the navigation device described above stores all the meshes in all layers covering the wide area meshes 82 to 84 as shown in FIG. Record. However, since the guiding path 93 passes only a small part of the wide area mesh 84, the guiding path 93 does not pass through most of the middle area mesh and the detailed mesh covering the area of the wide area mesh 84. Recording the mesh road data that does not pass through the guide route 93 may lead to waste of the storage medium.

  In view of the points described above, the present invention aims to suppress the amount of road data to be recorded on a storage medium in a navigation device that acquires and records the mesh road data through which a guidance route passes. .

  The invention described in claim 1 for achieving the above object comprises a road data acquisition device, a storage medium, a guidance route selection means for selecting a guidance route to an input destination, and the road data acquisition device. Road data recording means for acquiring road data including a guidance route selected by the guidance route selection means in units of areas based on geographical divisions (hereinafter referred to as meshes) and recording them in the storage medium; and the storage Road map display control means for displaying a road map on a display device based on road data including the guidance route recorded on the medium, and the guidance route selection means is a route having a smaller number of meshes to pass. However, the navigation apparatus is characterized in that the guide route to the input destination is selected by a method that makes it easier to select the guide route.

  In such a navigation device, the mesh road data through which the selected guide route passes is acquired and recorded in a storage medium, and the road map is displayed on the display device based on the recorded road data. Since the number of meshes through which the selected guide route passes tends to decrease, the amount of road data recorded in the storage medium can be suppressed.

  According to a second aspect of the present invention, in the navigation device according to the first aspect, the road data acquisition device acquires the road data recorded in a road data storage medium by reading the road data, and stores the road data storage The medium is a storage medium removable by a user.

  Thus, after the road data is recorded on the storage medium, the navigation device can display the road map along the guidance route even if the road data storage medium is removed.

  In the navigation device according to claim 1 or 2, the guidance route selection means selects a provisional guidance route to the destination, and the provisional guidance route. Has a return partial path that enters the second mesh next to it from the first mesh and enters the first mesh from the second mesh without passing through another mesh. A route obtained by replacing the return partial route of a typical guide route with an alternative partial route that passes only through the first mesh is selected as a guide route.

  In this way, the navigation device selects a guidance route that does not pass through the second mesh by replacing the return partial route with the alternative partial route when selecting the guidance route, and thus the mesh through which the selected guidance route passes. The number tends to decrease.

  According to a fourth aspect of the present invention, in the navigation device according to any one of the first to third aspects, the road data acquisition device includes upper hierarchy data including link and node data, and the upper hierarchy data. Hierarchical road data having lower hierarchical data including link and node data not including hierarchical data is acquired, and the navigation device uses the road data acquisition device to determine the guidance route selected by the guidance route selection means. Using the road data acquisition device and the upper layer data recording means for acquiring the upper layer data including the area based on the geographical division for the upper layer (hereinafter referred to as the upper mesh) and recording it in the storage medium The lower hierarchy data including the guidance route selected by the guidance route selection means is based on the geographical division for the lower hierarchy. Lower layer data recording means for acquiring a region (hereinafter referred to as a lower mesh) and recording it in the storage medium, wherein the guiding route selecting means has a lower number of upper meshes to pass through and the lower meshes to pass through. A route having a smaller number is selected in a manner that makes it easier to be selected as a guide route, and a guide route to the input destination is selected.

  As described above, the navigation device that acquires the mesh hierarchical road data of the mesh through which the selected guide route passes, records the data on the storage medium, and displays the road map on the display device based on the recorded road data. , The number of upper meshes and lower meshes through which the selected guide route passes tends to decrease, so that the amount of road data recorded in the storage medium can be suppressed.

  The invention according to claim 5 acquires hierarchical road data having upper hierarchy data including link and node data and lower hierarchy data including link and node data not including the upper hierarchy data. The road data acquisition device, the storage medium, the guidance route selection means for selecting the guidance route to the input destination, and the guidance data selected by the guidance route selection means using the road data acquisition device Using the road data acquisition device, the upper layer data recording means for acquiring the upper layer data as a unit based on the geographical division for the upper layer (hereinafter referred to as the upper mesh) and recording it in the storage medium, A geographical section for the upper layer that overlaps the upper mesh that is acquired and recorded by the upper layer recording means from the lower layer data. A plurality of lower meshes obtained by excluding lower meshes that do not pass through the guide route selected by the guide route selection means from among the areas based on the geographical subdivisions for the lower layers (hereinafter referred to as lower meshes) are acquired and stored. Low-level data recording means for recording on a medium, and road map display control means for displaying a road map on a display device based on road data including the guidance route recorded on the storage medium. It is a navigation device.

  Thus, in the navigation device that acquires hierarchical road data in units of meshes and records them in a storage medium and displays a road map on a display device based on the recorded road data, road data is acquired and Of the lower meshes that overlap the recorded upper meshes, the lower meshes (part or all) that do not pass through the selected guide route are excluded from acquisition and recording. The amount of road data to be recorded can be reduced.

  Note that when a part or all of the geographic area covered by the lower mesh coincides with a part of the geographic area covered by the upper mesh, the lower mesh is said to geographically overlap the upper mesh.

  Further, the invention according to claim 6 is the navigation device according to claim 5, wherein the road data acquisition device acquires the hierarchical road data recorded in the hierarchical road data storage medium by reading the hierarchical data, The hierarchical road data storage medium is a storage medium removable by a user.

  Thus, after the road data is recorded on the storage medium, the navigation device can display the road map along the guidance route even if the road data storage medium is removed.

  According to a seventh aspect of the present invention, a computer uses a road data acquisition device to acquire road data including a selected guidance route in units of areas (hereinafter referred to as meshes) based on geographical divisions. A road data recording means for recording on a storage medium, and a program for functioning as road map display control means for displaying a road map on a display device based on road data including the guide route recorded on the storage medium. The guide route selecting means selects a guide route to the input destination in such a way that a route having a smaller number of meshes to pass is more easily selected as a guide route. It is.

  By executing such a program in the navigation device, mesh road data through which the selected guidance route passes is acquired and recorded in a storage medium, and a road map is displayed on the display device based on the recorded road data. In the navigation device to be displayed, the number of meshes through which the selected guide route passes tends to decrease, so that the amount of road data recorded in the storage medium can be suppressed.

  According to an eighth aspect of the present invention, there is provided a computer having a hierarchical structure road data having upper hierarchy data including link and node data and lower hierarchy data including link and node data not including the upper hierarchy data. Using the road data acquisition device that acquires the above-described data, the upper layer data including the selected guidance route is acquired in units of areas based on the upper-layer geographic division (hereinafter referred to as upper mesh) and recorded in a storage medium. The upper hierarchy data recording means, the road data acquisition device, and the lower hierarchy data that is geographically overlapped with the upper mesh acquired by the upper hierarchy recording means from the lower hierarchy data and smaller than the geographical division for the upper hierarchy The guidance route selected by the guidance route selection means in the area based on the geographical division (hereinafter referred to as the lower mesh) Based on road data including a lower layer data recording means for acquiring and recording a plurality of lower meshes from which lower meshes that do not pass are recorded in the storage medium, and road data including the guide route recorded in the storage medium Is a program for functioning as a road map display control means for displaying on the display device.

  By executing such a program in the navigation apparatus, the navigation apparatus that acquires hierarchical road data in units of meshes, records the data in a storage medium, and displays a road map on the display device based on the recorded road data. Of the lower meshes that overlap geographically with the upper mesh from which road data is acquired / recorded, the lower meshes that do not pass the selected guide route are excluded from acquisition / recording, and are recorded in the storage medium accordingly. The amount of road data to be reduced can be reduced.

  Hereinafter, an embodiment of the present invention will be described. In FIG. 1, the hardware block diagram of the vehicle navigation apparatus 1 which concerns on this embodiment is shown. The vehicle navigation device 1 includes a position detector 11, an operation switch group 12, an image display device 13, an audio circuit 14, a speaker 14a, a microphone 14b, a VICS receiver 15, a RAM 16, a ROM 17, a map data reader 18, and an external DRAM 19. And a control circuit 20.

  The position detector 11 includes a well-known sensor (not shown) such as a geomagnetic sensor, a gyroscope, a vehicle speed sensor, and a GPS receiver. The current position and direction of the vehicle based on the characteristics of each of these sensors. Is output to the control circuit 20.

  The operation switch group 12 includes a plurality of mechanical switches provided in the vehicle navigation device 1 and an input device such as a touch panel provided so as to overlap the display surface of the image display device 13. A signal based on the touch is output to the control circuit 20.

  The image display device 13 displays a video based on the video signal output from the control circuit 20 to the user. Examples of the display image include a map centering on the current location.

  The audio circuit 14 outputs an audio signal based on the audio data received from the control circuit 20 to the speaker 14 a and outputs audio data based on the audio signal detected by the microphone 14 b to the control circuit 20.

  The VICS receiver 15 is a wireless receiver that receives road congestion information, traffic regulation information, and the like wirelessly transmitted from roadside equipment installed along the road and outputs the information to the control circuit 20.

  The map data reader 18 is a device that allows a user to freely attach and detach portable map data storage media and audiovisual data storage media, and reads data from the attached storage media based on control of the control circuit 20. It is. Examples of the map data reader 18 include a CD drive and a DVD drive, and examples of the map data storage medium include a map data CD-ROM and a map data DVD-ROM. Examples include music CDs and movie DVD-ROMs.

  The map data CD-ROM and map data DVD-ROM stored in the map data reader 18 in the present embodiment store map data including the position and type of the link and node, information on the connection relationship between the node and link, and the like. It has road data and facility data. The map data has a three-level hierarchical structure. That is, the map data includes three hierarchical data: wide area data, middle area data, and detailed data. Each hierarchical data has road data and facility data. And the geographical range in which each hierarchical data has road data and facility data, that is, the coverage area of each hierarchical data is mutually coincident. FIG. 2 conceptually shows the hierarchical structure of the map data. In the figure, a single rectangle at the top represents wide area data of the highest hierarchy, and a set of a plurality of rectangles at the bottom represents detailed data of the lowest hierarchy, and the top and bottom A plurality of rectangles in between represent middle-range data in an intermediate hierarchy. The area covered by the rectangle of each hierarchical data from the top represents the cover area of the hierarchical data.

  The difference between the hierarchical data is the amount of map data and facility data that each has. The higher the hierarchy data, the thinner the links and nodes included in the map data and the number of facilities included in the facility data compared to the lower hierarchy data. For example, for road data, detailed data includes all links and nodes in the area including narrow streets, mid-range data includes links and nodes excluding narrow streets from detailed data, and wide-area data includes medium links. It includes links and nodes only for major roads such as national roads and expressways, excluding prefectural roads from regional data.

In addition, the cover area of each hierarchical data is partitioned in a grid pattern with a predetermined roughness that is different for each hierarchical level. Specifically, the higher the hierarchical data, the coarser the section. In the following, each area where the wide area data is divided is referred to as a wide area mesh, each area where the intermediate area data is divided is referred to as a medium area mesh, and each area where detailed data is divided is referred to as a detailed mesh. . As a result of such a division for each hierarchy, the coverage area of one wide area mesh matches the set of cover areas of a plurality of middle area meshes, and the cover area of one middle area mesh is covered by a plurality of detailed meshes. It matches the set of areas.
Hereinafter, a middle mesh that covers a part of the coverage area of a certain wide area mesh is referred to as a child mesh of the wide area mesh. In addition, a detailed mesh that covers a part of the cover area of a certain mid-range mesh is called a child mesh of the mid-range mesh. A child mesh of a child mesh of a wide area mesh is called a grandchild mesh of the wide area mesh.

  The external DRAM 19 is a storage medium having a capacity capable of recording a part of the map data read from the map data reader 18.

  The control circuit (corresponding to a computer) 20 executes a program for the operation of the vehicle navigation apparatus 1 read from the ROM 17, and in executing the program, from the RAM 16, the ROM 17, the map data reader 18, and the external DRAM 19. Information is read, information is written to the RAM 16 and the map data reader 18, and signals are exchanged with the position detector 11, the operation switch group 12, the image display device 13, and the audio circuit 14.

  Specific processing performed by the control circuit 20 executing the program includes current position specifying processing, guidance route selection processing, route guidance processing, data saving processing, audiovisual reproduction processing, and the like.

  The current position specifying process is a process for specifying the current position and direction of the vehicle based on a signal from the position detector 11 using a known technique such as map matching. In the following description, it is assumed that the current position used by the control circuit 20 is the current position specified by the current position specifying process.

  The guide route selection process is a process of receiving an input of a destination by the user from the operation switch group 12 or the voice circuit 14 and selecting an optimum guide route from among possible routes from the current position to the destination.

  In the route guidance process, map data is read from the map data reader 18 and an image obtained by superimposing the selected guidance route, destination, waypoint, current position, etc. on the road map indicated by the map data is displayed on the image display device 13. This is a process of outputting a guidance voice signal for instructing a right turn, a left turn, etc. to the voice circuit 14 when necessary, for example, when the host vehicle arrives before the guidance intersection.

  The data saving process is a process performed by the control circuit 20 prior to the execution of the route guidance process, and the map data along the guidance route is selected from the map data storage medium inserted in the map data reader 18 as a minimum unit. The map data is read out and the read map data is recorded in the external DRAM 19.

  In the audio visual reproduction process, the music data recorded in the audio visual data storage medium inserted in the map data reader 18 is output to the audio circuit 14 or a video image based on the image data is displayed on the image display device 13. It is.

  In the present embodiment, when the map data storage medium is attached to the map data reader 18, the control circuit 20 determines the guide route by the guide route selection process, and then performs the data save process to the map data storage medium. A part of the map data in the map is copied to the external DRAM 19 and then the storage medium mounted on the map data reader 18 is replaced from the map data storage medium to the audiovisual data storage medium. Replay processing is executed in parallel. When the route guidance process and the audio visual reproduction process are executed in parallel, the control circuit 20 outputs the music data to the voice circuit 14 and uses the map data in the external DRAM 19 to image the road map including the guidance route. It is displayed on the display device 13. At this time, when the audio visual reproduction process displays the video image on the image display device 13, the control circuit 20 causes the image display device 13 to display a road map on one side and a divided screen representing the video image on the other side. Display may be performed. A function that achieves both reproduction of the audiovisual data storage medium and road map display realized by the processing of the control circuit 20 is called a corridor function.

  For this corridor function, the control circuit 20 executes the guidance route calculation program 100 shown in FIG. 3 as guidance route selection processing. In the execution of the guidance route calculation program 100, the control circuit 20 first receives a destination input by the operation switch group 12 or the microphone 14b in step 110, and then calculates a temporary guidance route in step 120. The provisional guidance route may be calculated by any method. For example, among the possible routes that can be reached from the current location to the destination, the route with the lowest total cost for each link in the possible route is selected. There is a method of using a temporary guidance route. At this time, for example, the cost of the link becomes larger as the length of the link is longer, and the value is higher for the link after the right / left turn than for the link that is not so, and the link is the one after passing the traffic light. The value becomes larger than the one that is not, the value becomes larger as the link congestion degree acquired by the VICS receiver 15 becomes larger, and the value becomes larger than the case where the link is the main road as a narrow street. Calculate by such a calculation.

  In this embodiment, since the map data has a hierarchical structure, provisional guidance route calculation is also performed hierarchically. Specifically, first, a route from the vicinity of the current position to the vicinity of the destination (for example, the lowest cost) (hereinafter referred to as a wide area route) is selected from the main roads included in the wide area data. Subsequently, of the roads included in the mid-range data, a route (for example, the lowest cost) connecting from the vicinity of the current position to the wide-area route (hereinafter referred to as the first mid-range route), and from the wide-area route to the vicinity of the destination A route that connects (for example, the lowest cost) (hereinafter referred to as a second mid-range route) is selected. Subsequently, among the roads included in the detailed data, the route (hereinafter referred to as the first detailed route) that leads from the current position to the first middle region route (hereinafter referred to as the first detailed route), and the second middle region route A route that is connected to the ground (for example, the lowest cost) (hereinafter referred to as a second detailed route) is selected. Then, a route that is connected in the order of the first detailed route → the first middle region route → the wide region route → the second middle region route → the second detailed route is set as a temporary guidance route.

  FIG. 4 shows an example of the temporary guidance route selected at step 120. In this figure, the provisional guidance route 27 from the current position 25 to the destination 26 passes through the wide area meshes 31-34.

  Subsequently, in step 130, it is determined whether or not there is a return partial route on the wide area mesh in the current provisional guidance route. The return partial path on the wide area mesh is equivalent to an area mesh A (corresponding to an example of the first mesh) to a neighboring wide area mesh B (corresponding to an example of the second mesh) in the current temporary guidance path. ) And return to the wide area mesh A from the wide area mesh B without passing through another wide area mesh. For example, in the temporary guidance route 27 in FIG. 4, a partial route that enters the wide area mesh 34 from the wide area mesh 32 and then returns from the wide area mesh 34 to the wide area mesh 32 corresponds to a return partial path on the wide area mesh. If there are one or more return partial paths on the wide area mesh, then step 140 is executed, and if there are none, step 150 is executed subsequently.

  In step 140, each of the returned partial paths on the wide area mesh found in the immediately preceding step 130 is replaced with an alternative partial path. This alternative partial path is a corresponding return partial path (that is, a path that enters from the wide area mesh A to the adjacent wide area mesh B and returns from the wide area mesh B to the wide area mesh A without passing through another wide area mesh). This is a partial path having the same end point and not coming out of the wide area mesh A to another mesh.

  FIG. 5 shows the temporary guidance route 28 after the turned-back partial route on the wide area mesh is replaced with the alternative partial route in the temporary guidance route 27 of FIG. 4. In this example, the return partial path on the wide area mesh is replaced with the alternative partial path, so that the provisional guidance path 28 generated as a result does not pass through the wide area mesh 34. After step 140, step 130 is executed again. By repeating these steps 130 and 140, the replacement from the return partial path to the alternative partial path is repeated until there is finally no return partial path on the wide area mesh from the temporary guidance path.

  Note that, for a certain temporary guidance route, even if all of the return partial routes on the wide area mesh are replaced with the alternative partial route in one step 140, the temporary guidance route after the replacement is performed in the subsequent step 130. However, in the case of having a return partial path on the wide area mesh, for example, in the wide area meshes 61 to 63 arranged vertically, as shown in FIG. 6A, the wide area mesh 61 → the wide area mesh 62 → the wide area mesh 63. The provisional guidance route 64 that follows the route of the wide area mesh 62 → the wide area mesh 61 is temporarily replaced by the replacement of step 140 to follow the route of the wide area mesh 61 → the wide area mesh 62 → the wide area mesh 61 as shown in FIG. This is a case where the route changes to the guide route 65. In the example of FIG. 6, the provisional guidance path 65 finally passes only the wide area mesh 61 among the wide area meshes 61 to 63 as shown in FIG. The temporary guidance path 66 is changed.

  If no alternative partial path corresponding to the return partial path on the wide area mesh is found in step 140, the return partial path is not replaced, and in the subsequent step 130, the return partial path is It may be considered that it is not a turn-back partial path on the mesh.

  In step 150, it is determined whether or not there is a return partial route on the mid-range mesh in the current provisional guidance route. The return partial path on the mid-range mesh refers to a mid-range mesh C (corresponding to an example of the first mesh) to an adjacent mid-range mesh D (example of the second mesh) in the current temporary guidance path. And a partial path that returns from the mid-range mesh D to the mid-range mesh C without passing through another mid-range mesh. Here, FIG. 7 shows the positional relationship between the portion of the provisional guidance path 28 shown in FIG. 5 passing through the wide area mesh 32 and the child mesh of the wide area mesh 32. As shown in this figure, the provisional guidance path 28 includes a middle mesh 321 to 324 which is a child mesh of the wide mesh 32, a middle mesh 322 → middle mesh 324 → middle mesh 323 → middle mesh 321 → middle. The meshes 323 are passed in this order. In such a temporary guidance route 28, a partial route that enters the middle region mesh 321 from the middle region mesh 323 and then returns to the middle region mesh 323 corresponds to a return partial route on the middle region mesh. If there are one or more return partial paths on the mid-range mesh, then step 160 is executed, and if there are none, step 170 is executed subsequently.

  In step 160, each of the returned partial paths on the mid-range mesh found in the immediately preceding step 140 is replaced with an alternative partial path. This alternative partial path enters the corresponding middle part mesh D from the corresponding return part path (that is, the middle part mesh C and returns to the middle part mesh C from the middle part mesh D without passing through another middle part mesh). Such a route is a partial route that has the same end point as that of the middle route mesh C and does not come out to other meshes.

  FIG. 8 shows the provisional guidance path 29 after the turned-back partial path on the mid-range mesh is replaced with the alternative partial path in the provisional guidance path 27 of FIG. In this example, the return partial path on the mid-range mesh is replaced with the alternative partial path, so that the temporary guide path 29 generated as a result does not pass through the mid-range mesh 321. After step 160, step 150 is executed again. By repeating the steps 150 and 160, the replacement from the return partial path to the alternative partial path is repeated until there is finally no return partial path on the intermediate mesh from the temporary guidance path.

  If no alternative partial route corresponding to the return partial route on the mid-range mesh is found in step 160, the return partial route is not replaced, and in the subsequent processing of step 150, the return partial route is It may be considered that the route is not a turn-back partial path on the mid-range mesh.

  In step 170, the current temporary route is selected as the determined guide route, and then the execution of the guide route calculation program 100 is terminated.

  When the control circuit 20 executes the guidance route calculation program 100 as described above, the vehicle navigation device 1 selects a provisional guidance route to the input destination (see step 110) (step 120). When the temporary guidance route has a return partial route on the wide area mesh (see step 130), the process of replacing the return partial route with the alternative partial route (step 140) is performed from the temporary guidance route. The process is repeated until there is no return partial path on the wide area mesh, and then a temporary guidance path having no return partial path on the wide area mesh has a return partial path on the medium area mesh (see step 150). ), The process of replacing the return partial path with the alternative partial path (step 160) from the guidance path Repeatedly until there is no return partial path on the area mesh, and the resulting temporary guidance path that has no return partial path on the wide area mesh and no return partial path on the intermediate area mesh is defined as the fixed guidance path Select (see step 170).

  In this way, the vehicle navigation apparatus 1 replaces the return partial path on the wide area mesh and the return partial path on the medium area mesh with the alternative partial path when selecting the guidance route, so that the vehicle navigation apparatus 1 temporarily enters from the original mesh. The route that returns to the original mesh as it is is changed to a route that stays in the original mesh, and the route after the change is selected as a fixed guide route. The number of area meshes tends to decrease, and the amount of map data stored in the external DRAM 19 can be suppressed.

  Further, the control circuit 20 executes a map data saving program 200 shown in FIG. 9 in order to realize the data saving process. In the execution of the map data saving program 200, the control circuit 20 firstly includes a wide area mesh (step 210) that includes any part of the entire route of the guidance route selected by the guidance route selection process. That is, only a wide area mesh through which the guidance route passes is selected, and only the wide area data corresponding to the selected wide area mesh is read from the map data storage medium using the map data reader 18 and copied to the external DRAM 19. Subsequently, in step 220, only the mid-range meshes including any part of the entire route of the guidance route are selected from the mid-range meshes, and these are selected from the map data storage medium using the map data reader 18. Only the mid-range data corresponding to the area mesh is read and copied to the external DRAM 19. Subsequently, in step 230, only the detailed meshes including any part of the entire route of the guidance route are selected from the detailed meshes, and the selected detailed meshes are selected from the map data storage medium using the map data reader 18. Only the corresponding detailed data is read and copied to the external DRAM 19. After step 230, the execution of the map data saving program 200 ends.

  FIG. 10 shows an example of the determined guide route. In this figure, the guide route 43 from the current position 41 to the destination 42 passes through the wide area meshes 52 to 54 among the wide area meshes 51 to 54. Therefore, in this example, in step 210, wide area data corresponding to the wide area meshes 52-54 is copied from the map data storage medium to the external DRAM 19.

  FIG. 11 shows the positional relationship between each of the child meshes and grandchild meshes of the wide area mesh 52, the wide area mesh 53, and the wide area mesh 54 and the guide path 43. Among the mid-range meshes 531 to 534 that are the child meshes of the wide-area mesh 53 shown in the middle left column of FIG. 11, the guide route 43 passes through three of the mid-range meshes 531, 532, and 533. In addition, among the mid-range meshes 541 to 544 that are child meshes of the wide-area mesh 54 shown in the middle middle row of FIG. 11, only the mid-range mesh 541 passes through the guide path 43. In addition, among the mid-range meshes 521 to 524 that are the child meshes of the wide-area mesh 52 shown in the middle row in the middle of FIG. 11, the mid-range meshes 521, 522, and 523 pass through the guide path 43. Therefore, in this example, in step 220, only the mid range data corresponding to the mid range mesh 531, 532, 533, 541, 521, 522, 523 among the child meshes of the wide range mesh 52-54 is stored in the map data. Copied from the medium to the external DRAM 19.

  In addition, among the detailed meshes 5311 to 5344 that are grandchild meshes of the wide area mesh 53 shown in the lower row in the middle of FIG. 11, the guide path 43 passes through the detailed meshes 5322, 5324, 5323, 5314, 5332, 5334, and 5333. Seven. Of the detailed meshes that are grandchild meshes of the wide area mesh 54 shown in the middle row of FIG. 11, only the detailed mesh 5411 passes through the guide path 43. Also, among the detailed meshes that are grandchild meshes of the wide area mesh 52 shown in the middle right column of FIG. 11, only the detailed meshes 5223, 5214, 5232, 5231, and 5233 pass through the guide path 43. Therefore, in this example, in step 230, among the grandchild meshes of the wide area meshes 52 to 54, the detailed meshes 5322, 5324, 5323, 5314, 5332, 5334, 5333, 5411, 5223, 5214, 5232, 5231, 5233 are changed. Only the corresponding detailed data is copied from the map data storage medium to the external DRAM 19.

  When the control circuit 20 executes such a map data saving program 200, the vehicle navigation apparatus 1 obtains hierarchical map data in units of meshes and copies it from the map data storage medium to the external DRAM 19. Since all of the sub-mesh that does not pass the selected guide route among the child meshes and grandchild meshes of the copied wide-area mesh are excluded from the copy target, it corresponds to the child meshes and grandchild meshes of the copied wide-area mesh. Compared with the case where all map data is copied to the external DRAM 19, the amount of copy data is greatly reduced.

  In the above embodiment, the map data reader 18 is an example of a road data acquisition device, the map data storage medium is an example of a road data storage medium and an example of a hierarchical structure data storage medium, and the external DRAM 19 is an example of a storage medium. An example. Further, the control circuit 20 functions as an example of a guidance route selection unit by executing the guidance route selection program 100, and functions as an example of a road data recording unit by executing the map data saving program 200. By executing the route guidance function, it functions as an example of a road map display control means.

  The map data is an example of road data and an example of hierarchical road data, and the wide area mesh, the intermediate area mesh, and the detailed mesh are examples of meshes. In addition, in the relationship between the wide area data and the middle area data, the wide area data is an example of the upper layer data, the middle area data is an example of the lower layer data, the wide area mesh is an example of the upper mesh, and the middle area mesh is the lower layer data. An example. In addition, in the relationship between the mid range data and the detailed data, the mid range data is an example of the upper layer data, the detailed data is an example of the lower layer data, the mid region mesh is an example of the upper mesh, and the detailed mesh is the lower layer data. An example. In addition, in the relationship between the wide area data and the detailed data, the wide area data is an example of the upper layer data, the detailed data is an example of the lower layer data, the wide area mesh is the 0 example of the upper mesh, and the detailed mesh is an example of the lower mesh. Become.

Further, regarding the relationship between the wide area data and the intermediate area data, the control circuit 20 executes step 210 of the map data saving program 200, thereby functioning as an example of the upper layer data recording means and executing step 220. Thus, it functions as an example of the lower layer data recording means. Further, regarding the relationship between the mid-range data and the detailed data, the control circuit 20 executes step 220 of the map data saving program 200, thereby functioning as an example of the upper layer data recording means and executing step 230. Thus, it functions as an example of the lower layer data recording means. Further, regarding the relationship between the wide area data and the detailed data, the control circuit 20 executes step 220 of the map data saving program 200, thereby functioning as an example of upper layer data recording means, and executing step 230. It functions as an example of the lower layer data recording means.
(Other embodiments)
As mentioned above, although embodiment of this invention was described, the scope of the present invention is not limited only to the said embodiment, The various form which can implement | achieve the function of each invention specific matter of this invention is included. It is.

  For example, the sections separating the meshes in each layer do not necessarily have to be rectangular, and may have any shape, and need not have the same shape or the same size in the same layer. . Also, the geographic section may change (eg, depending on the average speed of the guidance route).

  Further, the cover areas of the hierarchical data of the map data do not have to coincide with each other, and are sufficient if they overlap.

  Further, the hierarchy of the map data may be two or four or more. If attention is paid only to the function of selecting the guidance route, the map data does not necessarily have a hierarchical structure.

  The control circuit 20 executes steps 120 to 160 in the execution of the guidance route selection program 100 based on the user's predetermined operation on the operation switch group 12 for executing the corridor function. The map data saving program 200 may be executed prior to the route guidance process.

  In addition, in the execution of the map data saving program 200, the control circuit 20 is configured to copy the mesh road data including any of the entire routes of the guidance route. The mesh road data including any one of the half steps of the guide route may be copied.

  Further, in the execution of the map data saving program 200, the control circuit 20 selects only the mesh including the guidance route selected by the guidance route selection process and the adjacent mesh among the meshes of the hierarchy in each layer. Alternatively, only the hierarchical data corresponding to the selected meshes may be read from the map data storage medium using the map data reader 18 and copied to the external DRAM 19. That is, the vehicle navigation apparatus 1 acquires map data corresponding to a plurality of lower meshes from which a part or all of the lower meshes that do not pass the guidance route selected by the guidance route selection means are excluded from the lower meshes. It would be enough if it was to be recorded on a storage medium.

  Further, the object for recording the road data acquired from the map data reader 18 does not need to be the external DRAM 19, and any storage medium that can be accessed by the control circuit 20 in the vehicle can be used. It may be a thing.

  The road data recorded in the storage medium accessible by the control circuit 20 does not necessarily have to be acquired from the map data reader 18. For example, when road data is recorded on a hard disk, the guidance route calculation processing of the present invention is also performed when road data is recorded in advance from the hard disk to the RAM 16 or the external DRAM 19 having a higher reading speed than the hard disk. And data saving processing is applicable. In this case, the hard disk drive is an example of a road data acquisition device, and the RAM 16 or the external DRAM 19 is an example of a storage medium.

  Further, for example, the vehicle navigation device 1 uses a wireless communication circuit (for example, a wireless LAN interface) (not shown) to transfer map data from a road data server on a data communication network such as the Internet to the hard disk or the external DRAM 19 of the vehicle navigation device 1. Even when downloading, the guidance route calculation processing and data saving processing of the present invention can be applied. In this case, the wireless communication circuit is an example of a road data acquisition device, and the hard disk and the external DRAM 19 are examples of a storage medium.

  Further, the control circuit 20 does not execute steps 150 and 160 in the execution of the guidance route calculation program 100, and if a negative determination is made in step 130, the control circuit 20 may subsequently execute step 170. Good.

  In addition, in the execution of the guidance route calculation program 100, the control circuit 20 turns back when the provisional guidance route having no return partial route on the middle mesh has the return partial route on the detailed mesh. The process of replacing the partial route with the alternative partial route is repeated until there is no return partial route on the detailed mesh from the provisional guidance route, and the return partial route on the wide area mesh generated as a result is also returned on the intermediate mesh. A temporary guidance route that does not have a partial route or a return partial route on the detailed mesh may be selected as a fixed guidance route.

  Further, in steps 130 to 170, when the partial route corresponding to the return partial route includes an expressway, the control circuit 20 may not consider the partial route as the return partial route. By doing so, the highway is not replaced by the alternative partial route.

  In addition, the control circuit 20 does not execute Steps 130 to 170, selects the guide route calculated in Step 120 as a confirmed guide route, and sets the cost of the link as a condition of the above embodiment in the calculation. In addition, it may be calculated as a value that increases as the number of times the link crosses the boundary between meshes.

  In other words, the guidance route selection process is to select a guidance route to the input destination in such a way that a route with a small number of meshes to pass is more easily selected as a guidance route. It ’s enough.

  Further, the guidance for the specified destination may not be guidance along the route as in the above-described embodiment, for example, simple guidance only in the relative direction to the destination with respect to the direction of the host vehicle. However, it may be guidance that only displays the destination on the road map.

  The navigation device of the present invention is not limited to the vehicle navigation device 1 as in the above-described embodiment, and may be a navigation device that can be carried by a person.

It is a hardware block diagram of the vehicle navigation apparatus 1 which concerns on embodiment of this invention. It is a figure which shows notionally the hierarchical structure of map data. 3 is a flowchart of a guidance route selection program 100 executed by a control circuit 20; It is a figure which shows the temporary guidance path | route 27 which passes along the wide area meshes 31-34. It is a figure which shows the temporary guidance path | route 28 which passes along the wide area meshes 31-33. It is a figure which shows notionally how a return partial path | route is replaced with a temporary guidance path | route repeatedly. It is a figure which shows the temporary guidance path | route 28 which passes along the mid-range mesh 321-324. It is a figure which shows the guidance path | route 29 which passes along the mid range mesh 322-324. 3 is a flowchart of a map data saving program 200 executed by a control circuit 20; It is a figure which shows the guidance path | route 43 which passes along the wide area meshes 51-54. It is a figure which shows the distinction of the mesh read to the external DRAM 19, and the mesh which is not read. It is a figure which shows the guidance path | route 73 which passes the meshes 81-84. It is a figure which shows notionally the hierarchical structure of road data. It is a figure which shows the guidance path | route 933 which passes along the meshes 81-84. It is a figure which shows the mesh read to a storage medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vehicle navigation apparatus, 11 ... Position detector, 12 ... Operation switch group,
13 ... Image display device, 14 ... Audio circuit, 14a ... Speaker, 14b ... Microphone,
15 ... VICS receiver, 16 ... RAM, 17 ... ROM, 18 ... Map data reader,
19 ... External DRAM, 20 ... Control circuit, 25, 41 ... Current position, 26,42 ... Destination,
27-29, 64-66 ... provisional guidance route,
31-34, 51-54, 61-63 ... wide area mesh,
100: Guide route calculation program, 200 ... Map data saving program,
321 to 324, 521 to 524, 531 to 534, 541 to 544...
5311-5411 ... Detailed mesh.

Claims (8)

A road data acquisition device;
A storage medium;
A guide route selection means for selecting a guide route to the input destination,
Road data including road data including a guidance route selected by the guidance route selection means using the road data acquisition device as a unit based on a geographical division (hereinafter referred to as a mesh) and recorded in the storage medium Recording means;
Road map display control means for displaying a road map on a display device based on road data including the guidance route recorded in the storage medium,
The navigation device characterized in that the guidance route selection means selects a guidance route to the input destination in such a way that a route having a smaller number of meshes to pass is more easily selected as a guidance route. . The road data acquisition device is obtained by reading the road data recorded in a road data storage medium,
The navigation device according to claim 1, wherein the road data storage medium is a storage medium removable by a user. The guidance route selection means selects a provisional guidance route to the destination, and the provisional guidance route enters the second mesh next to the first mesh and passes through another mesh. Without having a turn-back partial path that enters the first mesh from the second mesh, the turn-back partial path of the temporary guidance path is changed to an alternative partial path that passes only through the first mesh. The navigation device according to claim 1 or 2, wherein the replaced route is selected as a guidance route. The road data acquisition device acquires hierarchical structure road data having upper hierarchy data including link and node data, and lower hierarchy data including link and node data not including the upper hierarchy data,
The navigation device
Using the road data acquisition device, the upper layer data including the guide route selected by the guide route selection means is acquired in units of areas (hereinafter referred to as upper meshes) based on the geographical division for the upper layer, and Upper layer data recording means for recording in a storage medium;
Using the road data acquisition device, the lower hierarchy data including the guidance route selected by the guidance route selection means is obtained in units of areas (hereinafter referred to as lower meshes) based on the geographic division for the lower hierarchy, and A lower layer data recording means for recording on a storage medium,
The guidance route selection means guides the route to the input destination in such a way that a route with a smaller number of upper meshes passing through and a number of lower meshes passing through is more easily selected as a guidance route. The navigation device according to any one of claims 1 to 3, wherein a route is selected. Road data acquisition apparatus for acquiring hierarchical structure road data having upper hierarchy data including link and node data, and lower hierarchy data including link and node data not including the upper hierarchy data;
A storage medium;
A guide route selection means for selecting a guide route to the input destination,
Using the road data acquisition device, the upper layer data including the guide route selected by the guide route selection means is acquired in units of areas (hereinafter referred to as upper meshes) based on a geographical section for the upper layer, and Upper layer data recording means for recording in a storage medium;
Using the road data acquisition device, the geographical segment for the lower layer that is geographically overlapped with the upper mesh that is acquired and recorded from the lower layer data by the upper layer recording means and that is smaller than the upper layer geographical segment Lower layer data recording that acquires and records in the storage medium a plurality of lower meshes excluded from lower meshes that do not pass through the guide route selected by the guide route selection means in the area based on (hereinafter referred to as lower mesh) Means,
A navigation apparatus comprising: road map display control means for displaying a road map on a display device based on road data including the guidance route recorded in the storage medium. The road data acquisition device acquires by reading the hierarchical road data recorded in the hierarchical road data storage medium,
6. The navigation apparatus according to claim 5, wherein the hierarchical road data storage medium is a storage medium removable by a user. Computer
Road data recording means for acquiring road data including a selected guidance route using a road data acquisition device as a unit based on a geographical section (hereinafter referred to as a mesh) and recording it on a storage medium; and
A program for functioning as road map display control means for displaying a road map on a display device based on road data including the guide route recorded in the storage medium,
The guide route selecting means selects a guide route to an input destination in such a way that a route having a smaller number of meshes to pass is more easily selected as a guide route. Computer
Selected using a road data acquisition device for acquiring hierarchical road data having upper hierarchy data including link and node data and lower hierarchy data including link and node data not including the upper hierarchy data Upper layer data recording means for acquiring the upper layer data including the guide route as a unit based on a geographical division for the upper layer (hereinafter referred to as upper mesh) and recording it in a storage medium;
Using the road data acquisition device, an area based on a geographical division for a lower hierarchy that is geographically overlapped with an upper mesh acquired by the upper hierarchy recording means from the lower hierarchy data and smaller than the upper hierarchical geographic division A lower layer data recording means for acquiring a plurality of lower meshes from which a lower mesh that does not pass through the guidance route selected by the guidance route selection means is recorded and recorded in the storage medium; ,
A program for functioning as road map display control means for displaying a road map on a display device based on road data including the guide route recorded in the storage medium.

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