JP4668588B2 - Navigation device and route search method - Google Patents

Description

  The present invention relates to a navigation device, and more particularly to a route search technique for an in-vehicle navigation device.

  Some conventional navigation devices hold road data configured to be able to distinguish between a paved road and an unpaved road, and perform a route search after increasing the cost (for example, travel time) of the unpaved road ( For example, Patent Document 1). In Patent Document 1, by configuring in this way, the possibility that an unpaved road is included in the searched route is reduced.

JP 2000-74682 A

  However, the method of costing an unpaved road in Patent Document 1 has the following problems. Specifically, in Patent Document 1, the cost of a link constituting a route to a destination is calculated, and a link with an advantageous cost is selected. Therefore, for example, even if a cost is imposed on an unpaved road, the unpaved road may be more advantageous than the paved road. In such a case, a route including an unpaved road is searched. That is, in Patent Document 1, even if the user does not want to pass through an unpaved road, the user may be guided to an unpaved road.

  Moreover, a user may think that it does not want to enter an unpaved road again when it passes from an unpaved road to a paved road. However, since Patent Document 1 employs a method of selecting a route using the cost of a link, a route including an unpaved road may be selected again when the route goes out to a paved road. It is also conceivable that the unpaved road is not selected as the road constituting the route from the beginning. However, with this method, a route search cannot be performed when the periphery of the departure place is surrounded by an unpaved road.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the possibility that an unpaved road is included in a route to be searched for in a navigation device, and from the paved road to the unpaved road. It is to reduce the possibility of searching for a route entering the route.

  In order to solve the above-described problem, in the present invention, in the navigation device, when a link of a paved road is selected once during a route search, an unpaved link is not selected as a road constituting a subsequent route. To.

  For example, one aspect of the present invention is applied to a navigation device that searches for a recommended route from a departure point to a destination using link information included in map data.

  The link information includes road information indicating whether or not the link is a paved road for each link, and the navigation device uses the link information to determine the starting point and the destination. A route search means for searching for a recommended route composed of a plurality of links connecting the two, and the route search means uses the road information and is unpaved as a link connected to the exit of the link of the paved road. The recommended route is searched without selecting a route link.

  As described above, according to the present invention, when the navigation device selects a link indicating a paved road during the route search, the navigation device indicates an unpaved road as a link connected to the link indicating the paved road. A link constituting a recommended route to the destination is searched without selecting a link.

  Therefore, according to the present invention, even when there is an unpaved road that is advantageous in cost, a route including the unpaved road is not searched once after entering the paved road.

  Further, the present invention merely selects the unpaved road link as the link connected to the exit of the paved road link, and the unpaved road link as the link connected to the unpaved road link exit. There are no restrictions on the choice. In other words, the present invention does not restrict the selection of an unpaved road link until a paved road link is selected. Therefore, even when the periphery of the current position is surrounded by an unpaved road, a route search to the destination can be performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a schematic configuration of an in-vehicle navigation device to which the first embodiment of the present invention is applied will be described with reference to FIG.

  FIG. 1 is a schematic configuration diagram of an in-vehicle navigation device (hereinafter simply referred to as “navigation device”) to which the first embodiment of the present invention is applied.

  As shown in the figure, the navigation device includes an arithmetic processing unit 1, a display 2, a storage device 3 in which map data and the like are stored, a voice input / output device 4, an input device 5, a wheel speed sensor 6, and a geomagnetism. It has a sensor 7, a gyro 8, and a GPS (Global Positioning System) receiver 9.

  The arithmetic processing unit 1 is a central unit for processing various types of information provided to the user by the navigation device. For example, the current position is detected based on information output from the various sensors 6 to 8 and the GPS receiver 9. The arithmetic processing unit 1 reads out map data around the detected current position from the storage device 3, develops the read map data in graphics, and displays a mark indicating the current position on the display 2 in a superimposed manner. In addition, the arithmetic processing unit 1 searches for a recommended route connecting the current position and the destination instructed by the user, and guides the user using the voice input / output device 4 and the display 2. As will be described later, the arithmetic processing unit 1 of the present embodiment selects a link indicating a paved road when searching for a recommended route, and then selects a link indicating an unpaved road to the destination. Search for recommended routes.

  The display 2 is a unit that displays the image data generated by the arithmetic processing unit 1 and includes a CRT, a liquid crystal display, or the like. The signal S1 between the arithmetic processing unit 1 and the display 2 is generally connected by an RGB signal or an NTSC (National TV Standards Committee) signal.

  The storage device 3 is a unit that stores data such as map data corresponding to a multi-stage scale map from an overall view of the Japanese archipelago to detailed views of municipalities throughout the country. As the storage device 3, for example, a DVD device or a hard disk device can be used.

  Here, the structure of the map data will be described.

  FIG. 2 is a diagram schematically showing the data structure of map data stored in the storage device 3 according to the embodiment of the present invention.

  As shown in the drawing, the map data 310 is classified for each mesh region obtained by dividing the map into a plurality of parts. The map data 310 includes a mesh ID 311 for identifying a mesh area, and link data 312 of each link constituting a road included in the mesh area.

  The link data 312 includes a link ID 3121 for identifying a link, coordinate information 3122 of two nodes (start node and end node) constituting the link, and whether the road to which the link belongs is a “toll road” or “general road”. A road type 3123 indicating whether there is a link, a link type 3124 indicating whether the road indicated by the link is “paved road (referred to as paved road)” or “unpaved road (referred to as unpaved road)”, Link length information 3125 indicating the link length, link travel time (or travel time) information 3126, link ID (connection link ID) 3127 of each link connected to two nodes (start node, end node), etc. Have.

  In addition to the map data described above, the storage device 3 has a table (referred to as a conversion table) for specifying a mesh ID of a mesh region including a point specified by the coordinate information from the coordinate information. It is remembered.

  Returning to FIG. 1, the description will be continued. The voice input / output device 4 converts the message to the user generated by the arithmetic processing unit 1 into a voice signal and outputs it, recognizes the voice uttered by the user, and transfers the recognized content to the arithmetic processing unit 1. To do.

  The input device 5 is a unit that receives instructions from the user for selecting various functions of the navigation device, setting a destination, and the like. Hard switches such as a scroll key and a scale change key, Joystick, a touch panel pasted on the display 2, and the like Consists of.

  The sensors 6 to 8 and the GPS receiver 9 are used by the navigation device to detect the current position. The wheel speed sensor 6 measures the distance from the circumference of the wheel and the measured rotational speed of the wheel, and further measures the angle at which the moving body is bent from the rotational speed of the paired wheel. The geomagnetic sensor 7 detects the magnetism held by the earth and detects the direction in which the moving body is heading. The gyro 8 is composed of an optical fiber gyro and a vibration gyro, and detects an angle at which the moving body rotates. The GPS receiver 9 receives a signal from a GPS satellite and measures the distance between the mobile body and the GSP satellite and the rate of change of the distance with respect to three or more satellites to thereby determine the current position, travel direction, and travel of the mobile body. Measure orientation.

  Next, functions of the arithmetic processing unit 1 of the navigation device described above will be described with reference to FIG.

  FIG. 3 is a diagram for explaining a functional configuration of the arithmetic processing unit 1 according to the first embodiment of the present invention.

  As shown in the figure, the arithmetic processing unit 1 includes a setting unit 10, a current position detection unit 11, a data reading unit 12, a map match processing unit 13, a route search unit 14, a route guidance unit 15, a map display processing unit 16, and a graphic. A processing unit 17 is provided.

  The setting unit 10 receives a request from a user input to the input device 5 or the voice input / output device 4, and controls the arithmetic processing unit 1 so that processing corresponding to the requested content is executed. For example, when the user requests a search for a recommended route to go to the destination via the input device 5, the user requests the route search unit 14 to search for a recommended route from the current position to the destination.

  The current position detection unit 11 uses the distance data and the angle data obtained as a result of integrating the distance pulse data S5 measured by the wheel speed sensor 6 and the angular velocity data S7 measured by the gyro sensor 8, respectively. By integrating with the shaft, the current position (X ′, Y ′), which is the position after the vehicle travels, is periodically calculated from the initial value (X, Y). The current position detection unit 11 outputs the calculated current position to the map display processing unit 16 and outputs the calculated current position to the map match processing unit 13 every predetermined number of calculations. When the current position detection unit 11 acquires correction data for the current position from the map match processing unit 13 described later, the current position detection unit 11 outputs the correction data for the current position to the map display processing unit 16. Further, when the current position is requested from the route guidance unit 15, the current position detection unit 11 outputs the current position (or correction data for the current position) to the route guidance unit 15.

  Here, the current position detection unit 11 integrates the azimuth data S6 obtained from the geomagnetic sensor 7 and the angular velocity data S7 obtained from the gyro 8 in order to match the relationship between the rotation angle of the host vehicle and the traveling direction. With reference to the angle data, the absolute direction of the direction in which the vehicle is traveling is estimated. As the current position detector 11 integrates the data S5 of the wheel speed sensor 6 and the data S7 of the gyro 8 respectively, errors accumulate, so that the position data S8 obtained from the GPS receiver 9 in a certain time is also stored. A process for canceling the accumulated error is performed to obtain data on the current position.

  The data reading unit 12 reads, from the storage device 3, map data 31 in an area requested to be displayed on the display 2 or an area required for route search (including the current position and destination).

  The map match processing unit 13 performs map match processing for combining the map data around the current position read by the data reading unit 12 and the current position periodically detected by the current position detection unit 11. The map match processing unit 13 periodically corrects the current position and outputs data indicating the corrected current position to the current position detection unit 11.

  The route search unit 14 uses the Dijkstra method or the like to search for a route that reaches the destination at an optimal cost connecting the two specified points (current position, destination) using the link data 312 (see FIG. 2). To do. As will be described later, the route search unit 14 of the present embodiment considers whether a road is paved when performing a route search. Then, the route search unit 14 prevents a route that enters an unpaved road from a paved road from being searched. The processing performed by the route search unit 14 will be described in detail later.

  The route search unit 14 outputs data indicating the recommended route to the map display processing unit 16 in order to display the route obtained as a result of the search as a recommended route on the display 2. Further, the route search unit 14 outputs data indicating the searched recommended route to the route guidance unit 15.

  The route guidance unit 15 guides the user so as to reach the destination through the searched recommended route. Specifically, the route guidance unit 15 periodically acquires the current position from the vehicle position detection unit 11. Then, the route guidance unit 15 uses the acquired current position, the data indicating the recommended route acquired from the route search unit 14, and the map data read from the storage device 3 via the data reading unit 12. To the destination.

  The map display processing unit 16 receives the map data 310 in the area requested to be displayed on the display 2 from the storage device 3 via the data reading unit 12. The map display processing unit 16 receives the recommended route searched from the route search unit 14 and receives information on the current position from the current position detection unit 11. Then, the map display processing unit 16 generates a map drawing command for drawing a road, other map components, a current position, a destination, and a mark such as an arrow for route guidance on the screen of the display 2, The result is output to the graphics processing unit 17.

  The graphics processing unit 17 displays image data on the screen of the display 2 using the map drawing command generated by the map display processing unit 16.

  Next, the hardware configuration of the arithmetic processing unit 1 according to the present embodiment will be described.

  FIG. 4 is a diagram illustrating a hardware configuration of the arithmetic processing unit 1.

  As shown in the figure, the arithmetic processing unit 1 includes a CPU (central processing unit) 21, a RAM (Random Access Memory) 22 that temporarily stores programs and data executed by the CPU 21, and the above-described units (setting unit 10, A program for executing the functions of the current position detection unit 11, the data reading unit 12, the map matching processing unit 13, the route searching unit 14, the route guiding unit 15, the map display processing unit 16, and the graphics processing unit 17). A ROM (Read Only Memory) 23 stored in advance, a DMA (Direct Memory Access) 24 that transfers data between the memories and between the memory and each device, and a drawing controller that executes graphic drawing and performs display control 25, a video random access memory (VRAM) 26 for storing graphics image data, and converting the image data into RGB signals. A color palette 27 for conversion, an A / D converter 28 for converting an analog signal into a digital signal, an SCI (Serial Communication Interface) 29 for converting a serial signal into a parallel signal synchronized with the bus, and a parallel signal synchronized with the bus And a PIO (Parallel Input / Output) 30 mounted on the bus and a counter 31 for integrating the pulse signal. Then, each of the above units (setting unit 10, current position detection unit 11, data reading unit 12, map match processing unit 13, route search unit 14, route guidance unit 15, map display processing unit 16, and graphics processing unit 17). The function is realized by the CPU 21 loading a program for executing the function of each of the above units stored in the ROM 23 into the RAM 22 and executing it.

  Next, route search processing performed by the route search unit 14 of the navigation device of this embodiment will be described.

  First, an outline of the route search process will be described with reference to FIG.

  FIG. 5 is a diagram for explaining a flow of a route search process performed by the navigation device of the present embodiment.

  First, the route search part 14 receives the input of the destination from a user via the setting part 10 (S100). In this step, the route search unit 14 acquires the current position of the vehicle via the current position detection unit 11. In the following description, the case where the current position of the vehicle is the departure point is taken as an example, but the present invention is not particularly limited thereto. The route search unit 14 may accept an input of a departure place from the user via the setting unit 10.

  Subsequently, the route search unit 14 reads the link data 312 necessary for searching the recommended route from the storage device 3 via the data reading unit 12 (S101), and proceeds to the process of S102. Specifically, the route search unit 14 reads the conversion table from the storage device 3 and specifies the mesh ID of the mesh region including the point specified by the coordinate information from the coordinate information indicating the current position and the destination. Next, the route search unit 14 obtains each link data 312 registered in each map data having the identified mesh ID from the storage device 3 via the data reading unit 12.

  In S102, using the link data 312 read in S101, a link whose start node is the end node of the link (referred to as an incoming link) extracted from the heap table in S106, which will be described later, is a candidate for a link that constitutes a recommended route. Selected as a link (called an escape link). In addition, when there are a plurality of links having the end node of the entry link as a start node, a plurality of exit links are selected. In the case where the processing in S106 is not performed, that is, in the initial stage where the link is not registered in the heap table, instead of selecting the link having the end node of the extracted ingress link as the start node as a candidate link At least one link having the current position (or starting point) or close to the current position is selected as the exit link.

  Here, the heap table is a table for registering link data of a candidate link together with the total cost (for example, travel time) from the departure place to the end node of the candidate link, and is stored in a storage device such as a memory. Remembered.

  Subsequently, the route search unit 14 performs a paved / unpaved determination process for the selected escape link (S103), and proceeds to the process of S104. The pavement / unpaved determination process refers to a process of determining whether or not to adopt the escape link selected in S102. The paved / unpaved determination process will be described with reference to FIGS.

  In S104, the route search unit 14 calculates the total cost (total cost from the departure point to the end node of the exit link) of each exit link employed in S103. Specifically, using each link data 312 read in S101, the cost of the exit link adopted in S103 is added to the total cost of the link registered in the heap table, and the addition result is used as the exit link. The total cost of However, at the initial stage where no link is registered in the heap table, the cost of the exit link adopted in S103 is set as the total cost of the exit link. Then, the route search unit 14 adds the link data and the total cost of each candidate link to the heap table.

  Next, the route search unit 14 determines whether there is a link where the destination exists or is close to the destination (called a destination link) among the links newly added to the heap table in S104 performed immediately before. It is checked whether or not (S105). If it is determined that there is no destination link in S105, the route search unit 14 proceeds to the process of S106, and if it is determined that there is a destination link, the path search unit 14 proceeds to the process of S107.

  In S106, the route search unit 43 sorts the information on the links registered in the heap table in ascending order of the total cost, extracts the link located first, and so on, to obtain the link with the minimum total cost from the heap table. Extract. Then, the process returns to S1002.

  Next, the process of S107 that is performed when it is determined in S105 that there is a destination link will be described. In S107, the route search unit 14 performs recommended route determination processing. Specifically, a link that generates a destination link (referred to as a link having a destination link start node as an end node) is searched from the heap table, and the detected link is a link (configuration link) that constitutes a recommended route. Called). Next, it is checked whether or not the constituent link is a link where the departure place exists or is close to the departure place (referred to as a departure place link). If not, the link that generated this constituent link is searched. Then, the detected link is determined as a constituent link, and it is further checked whether or not it is a departure link. By repeating this process until it is determined that the configuration link is the departure link, each configuration link that constitutes the recommended route is determined. The route search unit 14 ends the process when the recommended route is determined.

  Next, the pavement / unpaved determination process in S103 of FIG. 5 will be described with reference to FIGS.

  FIG. 6 is a flowchart of the paved / unpaved determination process in the route search process performed by the navigation device of the present embodiment. FIG. 7 is a diagram for explaining the relationship between the entry link and the exit link. In the following description, as shown in FIG. 7, the case where the exit links 53 and 54 are extracted from the entrance link 52 in the above-described S103 will be described as an example.

  First, the route search unit 14 specifies one exit link from the exit links extracted in S102 of FIG. 5 (S200), and proceeds to the process of S201. Here, it is assumed that the route search unit 14 has identified the escape link 53.

  In S201, the route search unit 14 acquires the link type 3124 of the exit link from the link data 312 and proceeds to the process of S202.

  In S202, the route search unit 14 determines whether or not the escape link specified using the acquired link type 3124 is a paved road. The route determination unit 14 proceeds to the process of S203 when determining that the escape link is a paved road, and proceeds to the process of S210 when determined that the escape link is an unpaved road.

  In S210, the route search unit 14 acquires the link type 3124 of the entry link 52, and proceeds to the process of S211.

  In S211, the route search unit 14 determines whether the approach link is an unpaved road using the acquired link type 3124. The route determination unit 14 proceeds to the process of S203 when determining that the approach link is an unpaved road, and proceeds to the process of S212 when it is determined that the approach link is not an unpaved road.

  In S212, the exit link specified in S200 is not adopted as the link constituting the recommended route, and the process proceeds to S213.

  Subsequently, the process of S203 that is performed when it is determined that the escape link specified in S202 is a paved road and when the approach link is determined to be unpaved in S211 will be described. In S203, the route search unit 14 employs the escape link specified in S200 as a link constituting the recommended route.

  Thereafter, the route search unit 14 determines whether or not the above-described determination process (S200 to S212) has been performed for all the escape links extracted in S102 of FIG. 5, and ends the process when all the escape links are determined. To do. On the other hand, the route search part 14 returns to the process of S200, when determination about all the escape links extracted by S102 is not performed (S213). In the example of FIG. 7, the process ends when it is determined whether or not both the escape link 53 and the escape link 54 are adopted as links constituting the recommended route.

  Here, the process of FIG. 6 will be described with a specific example. For example, in the example shown in FIG. 7, it is assumed that the escape link 53 is an unpaved road and the approach link 52 is an unpaved road. In this case, the route search unit 14 performs the processing of S202, S210, and S211 and then proceeds to the processing of S203, and adopts the escape link 53 as a link constituting the recommended route. For example, it is assumed that the escape link 53 is an unpaved road and the entry link 52 is a paved road. In this case, the route search unit 14 proceeds to the processing of S212 after executing the processing of S202, S210, and S211, and does not employ the escape link 53 as a link constituting the recommended route.

  As described above, in the route search process, the route search unit 14 of the present embodiment does not use an unpaved road as a link connected to the paved road when the paved road is used as a link constituting the recommended route. Therefore, once a paved road link is selected, an unpaved road is not searched as a path following the link. In the present embodiment, selection of an unpaved link is permitted until a paved road link is selected in the route search. This is because the route search cannot be performed when all the links on the unpaved road are disabled.

  Subsequently, a second embodiment of the present invention will be described.

The second embodiment is a modification of the route search unit 14 included in the navigation device of the first embodiment. Specifically, in addition to the function of the route search unit 14 of the first embodiment, the route search unit 14 of the second embodiment has a function of selecting a route that enters a non-paved road from a paved road under predetermined requirements. It is what. In addition, 2nd Embodiment has the same structure except 1st Embodiment and the function of the route search part 14. FIG. In the description of the second embodiment, the same reference numerals are used for the same components as those in the first embodiment. In the description of the second embodiment, the description will focus on parts that are different from the first embodiment.

  The route search process according to the second embodiment will be described with reference to FIG.

  Now, the route search part 14 of 2nd Embodiment performs each process step shown in FIG. 5, and searches the recommended route to the destination. Specifically, the route search unit 14 of the second embodiment performs the processing of S100 to 103 according to the same procedure as that of the first embodiment. If one or more escape links can be employed in S103, the same processing as in the first embodiment described above is performed in S104. On the other hand, when no exit link can be employed in S103, the route search unit 14 retains data specifying an entrance link that cannot employ the exit link in S104. For example, the route search unit 14 registers a flag in association with an “entry link” that is registered in the heap table and cannot adopt an escape link. In the following, an example of registering flags in association with each other will be described. Subsequently, the route search unit 14 performs the process of S105 described above.

  When the process proceeds to S106 by the process of S105, the route search unit 14 extracts a link other than the link associated with the flag when extracting the link from the heap table, and returns to the process of S102. In S106, S102 to S105 performed when a link other than the link associated with the flag is extracted is the same as described above.

  Here, in S106, there is a case where there is no link that can be extracted (that is, a route search to the destination cannot be performed). In this case, the route search unit 14 deletes the flag registered in the heap table, performs link extraction, and proceeds to the processing of S102 to S103. When the link is extracted after deleting the flag registered in the heap table in S106, the route search unit 14 performs the pavement / unpaved determination process performed in S103 from the process illustrated in FIG. Change to the process shown in.

  Here, FIG. 9 shows an example in which a route search to the destination cannot be performed. FIG. 9 is a diagram illustrating a case where the destination is connected only to a link on an unpaved road. FIG. 9 shows a case where it is necessary to pass through either the unpaved road link 63 or the unpaved road link 64 in order to reach the destination 70. Also, a paved road link 62 and a paved road link 65 are connected to the unpaved road link 63 and the unpaved road link 64, respectively. In the illustrated example, it is assumed that the route search unit 14 performs the paved / unpaved determination process shown in FIG. In this case, the link 63 is not adopted as an exit link when the link 62 is routed. Similarly, the link 64 is not adopted as the exit link when the link 65 is routed. This is because, in the paved / unpaved judgment process of FIG. 6, the route that enters the unpaved road link from the paved road link is not selected. As a result, the route to the destination cannot be searched. Therefore, in the second embodiment, when the route to the destination cannot be searched, a process of selecting an unpaved link from the paved road links is performed. A route search retry process performed when a route to the destination cannot be searched will be described below.

  FIG. 8 is a flowchart of the paved / unpaved determination process performed by the navigation device of the second embodiment.

  First, the route search unit 14 performs processing for specifying the escape link extracted in S102 of FIG. Specifically, the exit link is specified by the same procedure as S200 in FIG. 6 (S300).

  Next, the route search unit 14 specifies the type of the approach link using the link data 312 and determines whether the approach link is a paved road (S301 to 302). As a result of the determination, if the approach link is a paved road, the process proceeds to S303, and if the approach link is not a paved road, the process proceeds to S310.

  In S310, the route search unit 14 acquires the type of the exit link using the link data 312. The route search unit 14 determines whether or not the escape link is a paved road, and proceeds to S312 when it is determined that the escape link is a paved road, and when it is determined that the escape link is not a paved road S303. Proceed to In S312, the route search unit 14 determines not to adopt the exit link as a link constituting the recommended route, and proceeds to the process of S313 (S312).

  Next, the process of S303 that proceeds when it is determined in S302 that the approach link is a paved road and when it is determined that the escape link is not a paved road in S311 will be described. In S303, the route search unit 14 employs the exit link specified in S300 as a link constituting the recommended route.

  Thereafter, the route search unit 14 determines whether or not the above-described determination process (S300 to S312) has been performed for all the escape links extracted in S102 of FIG. 5, and ends the process when all the escape links are determined. To do. On the other hand, the route search part 14 returns to the process of S300, when the determination about all the escape links extracted by S102 is not performed (S313).

  As described above, according to the second embodiment, the possibility that an unpaved road is included in the route to the destination can be reduced as in the first embodiment. Further, according to the second embodiment, the link that enters the unpaved road from the paved road when the destination is not reached without passing through the unpaved road is adopted. Therefore, as a result of performing the route search according to the same procedure as in the first embodiment, even when the route to the destination cannot be searched, the route can be searched by performing the above-described processing of FIG. Become.

  The present invention is not limited to the embodiment described above, and various modifications can be made within the scope of the gist of the present invention. For example, when the navigation device of the first embodiment performs a route search to a destination that does not reach unless the navigation device passes through an unpaved road, the route to the link that can be searched is held. Then, the route searching unit 14 may search for a route from the searched route to the destination regardless of a paved road or an unpaved road.

1 is a schematic configuration diagram of an in-vehicle navigation device to which an embodiment of the present invention is applied. It is a figure which shows the data structure of the map data memorize | stored in the memory | storage device 3 of embodiment of this invention in simulation. It is a figure for demonstrating the function structure of the arithmetic processing part 1 of embodiment of this invention. It is a figure which shows the hardware constitutions of the arithmetic processing part 1 of embodiment of this invention. It is a figure for demonstrating the flow of the process of the route search which the navigation apparatus of embodiment of this invention performs. It is a flowchart of the pavement / unpaved determination process in the process of the route search performed by the navigation device of the embodiment of the present invention. It is a figure for demonstrating the relationship between an approach link and an escape link. It is a flowchart of the pavement / unpaved judgment process in the process of the route search which the navigation apparatus of 2nd Embodiment performs. It is the figure which illustrated the case where the destination was connected only to the link of an unpaved road.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Arithmetic processing part, 2 ... Display, 3 ... Memory | storage device, 4 ... Voice input / output device, 5 ... Input device, 6 ... Wheel speed sensor, 7 ... Geomagnetic sensor, 8 ... Gyro, 9 ... GPS receiver, 10 ... Setting unit 11 ... Current position detection unit 12 Data reading unit 13 Map match processing unit 14 Route search unit 15 Route guidance unit 16 Map display processing unit 17 Graphics processing unit 21 ... CPU, 22 ... RAM, 23 ... ROM, 24 ... DMA, 25 ... Drawing controller, 26 ... VRAM, 27 ... Color palette, 28 ... A / D converter, 29 ... SCI, 30 ... PIO, 31 ... Counter

Claims (3)

A navigation device that searches for a recommended route from a starting point to a destination using link information included in map data,
The link information includes road information indicating whether the link is a paved road for each link,
Route search means for searching for a recommended route composed of a plurality of links connecting the departure point and the destination using the link information;
The route search means includes
Means for identifying one candidate link from among links that can be connected to the exit of an already searched link (entrance link);
Means for determining whether the candidate link is a paved road using the road information;
When the candidate link is a paved road, means for selecting the candidate link as a link constituting the recommended route;
If the candidate link is an unpaved road, means for further determining whether the approach link is a paved road using the road information;
When the approach link is an unpaved road, means for selecting the candidate link as a link constituting the recommended route;
And a means for not selecting the candidate link as a link constituting the recommended route when the approach link is a paved road. The navigation device according to claim 1,
The route search means includes
The navigation device, wherein when a recommended route from the starting point to the destination cannot be searched, the link of the unpaved road is selected as a link connected to the exit of the link of the paved road. A route search method performed by a navigation device that searches for a recommended route from a starting point to a destination using link information included in map data,
The link information includes road information indicating whether the link is a paved road for each link,
The navigation device
Using the link information, performing a step of searching a recommended route composed of a plurality of links connecting the departure place and the destination;
The step of searching for the recommended route includes:
Identifying one candidate link from among links that can be connected to the exit of an already searched link (entrance link);
Determining whether the candidate link is a paved road using the road information;
When the candidate link is a paved road, selecting the candidate link as a link constituting the recommended route;
If the candidate link is an unpaved road, further using the road information to determine whether the approach link is a paved road;
When the approach link is an unpaved road, selecting the candidate link as a link constituting the recommended route;
When the approach link is a paved road, a step of not selecting the candidate link as a link constituting the recommended route is performed.

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