JP2007263922A - Navigation system, road deciding method, and map data structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a navigation system capable of accurately determining start road, without imposing the user with a load. <P>SOLUTION: This navigation system comprises a first road acquisition means for retrieving map data, by using information indicative of an origin and for acquiring at least one of information on a road around the origin; a first distance calculation means for calculating a distance on the map information between a point closest to the origin on the road acquired by the first road acquisition means and the origin; a first road determination means for determining whether there is a place that vehicles cannot pass through, on a straight line connecting the origin and the closest point on the map data; and a start road determination means for determining the start road based on the calculation result by the first distance calculation means and the determination result by the first road determination means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a navigation system that performs route search with reference to predetermined map data. The present invention also relates to a road determination method for determining a departure road when searching for a route with reference to predetermined map data. Further, the present invention relates to a map data structure for causing a computer to determine a starting road and a destination road for route search.

Navigation systems that provide route guidance from the current position of a vehicle to a destination are widely known and put into practical use. For example, Patent Document 1 below discloses a navigation system that can perform route search while avoiding inaccessible places such as steep mountains and deep rivers.
Japanese Patent Application No. 2005-265464

  In various navigation systems including the above-mentioned Patent Document 1, route search is generally performed based on a logic called Dijkstra method. More specifically, the route search in the Dijkstra method is performed by calculation based on a link cost indicating a work amount required to pass through the links constituting the road. Each link connecting two branch points is weighted differently depending on the distance and the type of road. In addition, in the Dijkstra method, a route that minimizes the sum of the link costs (that is, a series of links connecting the current location to the destination) is selected as the optimum route.

  When performing a route search by the Dijkstra method, first, a road where the vehicle is located (or its vicinity) (hereinafter abbreviated as “departure road”) and a road near its destination (hereinafter abbreviated as “destination road”). ) Need to be determined. In determining these departure roads and destination roads, if the vehicle or destination is not located on the road existing in the map data of the navigation system, the current position of the vehicle is selected from the road data included in the map data. The closest road is set as the departure road, and the road closest to the destination is set as the destination road. The point closest to the vehicle on the departure road is set as the start point of the route, and the point closest to the destination on the destination road is set as the end point of the route, and the route search is executed.

  However, when the departure road and the destination road are determined as described above, the following problems may occur. This problem will be described with reference to FIG.

According to the example shown in FIG. 1, the vehicle is stopped at the position P. A river r flows beside it. Roads R ₁ , R ₂ , R ₃ are laid so as to surround three sides of the vehicle. When a route search according to the above algorithm is executed in such a situation, the distance between each of the roads R ₁ , R ₂ , R ₃ and the position P (more precisely, the position is determined) in order to determine the departure road. The distances d ₁ , d ₂ , d ₃ ) between the points P ₁ , S ₂ , S ₃ on each road that intersect the normal of each road passing through P and the position P are determined. In the example shown in FIG. 1, d ₁ <d ₂ <d ₃ . Therefore starting road is determined on the road R _1, the starting point of the path is set to a point S _1. As a result, the search path that starts from the point S ₁ is executed.

However river r is flowing between the vehicle and the road R _1. As shown in FIG. 1, for the vehicle to reach the point S ₁ include a method over directly to the other side enters the example river r. But this is not practical. Therefore, in order for the vehicle to reach the point S1, _first , there is nothing but driving on another road. In other words it can be said that the path that starts from the point S ₁ is one in which the wrong.

This problem can also occur at the destination. For example, when the position P of Figure 1 considered by replacing the destination, before as well as also the road R ₁ is determined on the purpose roads, it can be seen that the point S ₁ is set to the end point of the path. In practice should such a point S ₂ and S ₃ is set to the end point can be said to be those also incorrect route to the point S ₁ and the end point.

  That is, in the above algorithm, an incorrect route may be presented to the user. That is, in the conventional navigation system as described above, the start point and the end point of the route are set in error, and as a result, the correct route guidance may not be provided to the user.

Note For the start point of the route, the vehicle is acquired correct starting point by traveling to approach the road R ₂ and R _3, is performed immediately sama path modification. However, this means that the route search is initially performed at least twice, which can be extremely burdensome on the control system of the navigation system. In addition, the error at the end of the route is still not resolved.

  In order to avoid such a problem, for example, there is a method in which the user himself / herself designates the departure road and the destination road by manual operation. However, such an operation is a burden on the user and is not a desirable solution.

  In view of the above circumstances, an object of the present invention is to provide a navigation system and a road determination method that can determine a departure road more accurately without imposing a burden on the user. Another object of the present invention is to provide a navigation system and a road determination method that can determine the destination road more accurately. It is another object of the present invention to provide a map data structure suitable for realizing such a navigation system and road determination method.

  A navigation system for performing a route search with reference to predetermined map data according to an aspect of the present invention that solves the above-described problem searches the map data using information representing a departure place, and A first road acquisition means for acquiring at least one road information; and a closest point closest to the departure point, which is a distance on the map data, which is a point on the road acquired by the first road acquisition means A first distance calculating means for calculating a distance between the starting point and the starting point, and determining whether or not there is a place where the vehicle cannot pass on a straight line connecting the starting point and the closest point on the map data A system comprising: a first road determination unit; and a departure road determination unit that determines a departure road based on a calculation result by the first distance calculation unit and a determination result by the first road determination unit. is there

  According to the navigation system configured as described above, a road that can be directly entered without passing through another road is reliably determined as a departure road. As a result, a more accurate starting road determination is realized.

  In the navigation system, the departure road determining means operates to determine a road closest to the departure place as a departure road among roads where there is no place where the vehicle is prevented from passing between the departure place and the nearest point of contact. can do.

  The road determined by the starting road determining means that operates as described above has a very high possibility of actually becoming a starting road, and can be said to be suitable for route search.

  In addition, the navigation system searches the map data using destination acquisition means for acquiring destination information set by a predetermined user operation, and destination information acquired by the destination acquisition means, Second road acquisition means for acquiring at least one piece of road information around the destination, and the distance on the map data, the distance between the road acquired by the second road acquisition means and the destination A second distance calculating means for calculating the second road determining means for determining whether or not the destination can be reached from the road without passing through another road on the map data; The system may further include a destination road determination unit that determines a destination road based on a calculation result by the distance calculation unit and a determination result by the second road determination unit.

  According to the navigation system configured as described above, a road that can reach the destination without passing through another road is reliably determined as the destination road. As a result, more accurate determination of the destination road is realized.

  In the navigation system, the destination road determination means can operate to determine the road closest to the destination among the roads that can reach the destination without passing through other roads.

  The road determined by the destination road determination means that operates as described above is very likely to be a destination road, and can be said to be suitable for route search.

  A road determination method for determining a departure road when searching for a route with reference to predetermined map data according to an aspect of the present invention that solves the above-described problems is provided by using the map data using information representing a departure place. A first road acquisition step of acquiring at least one piece of road information around the departure place, and a distance on the map data, the point on the road acquired by the first road acquisition step A first distance calculating step for calculating a distance between the nearest point closest to the starting point and the starting point, and a place where the vehicle cannot pass on a straight line connecting the starting point and the closest point on the map data A first road determination step for determining whether there is a departure road, a departure road determination step for determining a departure road based on the calculation result of the first distance calculation step and the determination result of the first road determination step A method comprising the flop.

  According to such a road determination method, a road that can be directly entered without passing through another road is reliably determined as a departure road. As a result, a more accurate starting road determination is realized.

  In the departure road determination step, the road closest to the departure place may be determined as the departure road among roads where there is no place that prevents the vehicle from passing between the departure place and the closest point.

  The road determined in the departure road determination step is very likely to be a departure road, and can be said to be suitable for route search.

  The road determination method also includes a destination acquisition step for acquiring destination information set by a predetermined user operation and a search for the map data using the destination information acquired by the destination acquisition step. A second road acquisition step for acquiring at least one piece of road information around the destination, and a distance on the map data between the road acquired in the second road acquisition step and the destination A second distance calculating step for calculating a distance; a second road determining step for determining whether or not the destination can be reached from the road without passing through another road on the map data; A destination road determination step for determining a destination road based on the calculation result of the distance calculation step and the determination result of the second road determination step. There.

  According to such a road determination method, a road that can reach the destination without passing through another road is reliably determined as the destination road. As a result, more accurate determination of the destination road is realized.

  In the destination road determining step, the road closest to the destination may be determined as the destination road among the roads that can reach the destination without passing through other roads.

  A map data structure according to an aspect of the present invention that solves the above problem is for causing a computer to determine a departure road and a destination road for route search. The map data structure is associated with a predetermined coordinate system, includes a map image in which at least a road and a terrain are drawn, the road is defined by a first polyline corresponding to the coordinate system, and the vehicle passes. In order to make the computer recognize a place where the vehicle cannot travel, a boundary between a place where the vehicle can pass and a place where the vehicle cannot pass is defined by a second polyline corresponding to the coordinate system.

  According to such a map data structure, it is possible to make a computer recognize a place where a vehicle cannot pass. Therefore, by adopting this map data structure, it is possible to accurately determine the departure road and the destination road by a computer.

  According to the navigation system and the road determination method of the present invention, it is possible to determine the departure road more accurately without imposing a burden on the user. Further, according to the map data structure of the present invention, such a navigation system and road determination method can be suitably realized.

  The configuration and operation of the navigation system according to the embodiment of the present invention will be described below with reference to the drawings.

  FIG. 2 is a block diagram showing a configuration of the navigation system 100 according to the embodiment of the present invention. The navigation system 100 has a navigation function for guiding a user to a destination.

  The navigation system 100 includes a control unit 1, a GPS (Global Positioning System) receiver 2, a gyro sensor 3, a vehicle speed sensor 4, a recording medium 5, an input unit 6, a display unit 7, a ROM (Read Only Memory) 8, a DRAM (Dynamic Random An access memory (SRAM) 9, a static random access memory (SRAM) 10, a video random access memory (VRAM) 11, an FM signal processing unit 12, a beacon processing unit 13, a user interface 14, and an image processing unit 15. The control unit 1 operates to control the entire system in an integrated manner. Each component of the navigation system 100 executes various processes under the control of the control unit 1.

  The GPS receiver 2 captures and tracks some of the plurality of GPS satellites that orbit the earth. Then, position and velocity positioning is executed using the GPS signals from the respective GPS satellites received during acquisition / tracking. The GPS receiver 2 passes the calculated positioning result (hereinafter referred to as “GPS positioning” for convenience) to the control unit 1.

  The gyro sensor 3 and the vehicle speed sensor 4 are sensors for known dead reckoning (hereinafter abbreviated as “DR”). The gyro sensor 3 measures an angular velocity related to the direction of the vehicle on which the navigation system 100 is mounted, and outputs the measurement result to the control unit 1. The vehicle speed sensor 4 detects the rotational speeds of the left and right drive wheels of the vehicle, generates a vehicle speed pulse signal corresponding to the average speed, and outputs the vehicle speed pulse signal to the control unit 1. For convenience, these sensor outputs are referred to as “DR sensor outputs”.

  The recording medium 5 contains, for example, a CD (Compact Disc) or a DVD (Digital Versatile Disk) or a built-in HDD (Hard Disk Drive). The recording medium 5 stores navigation data necessary when the navigation system 100 performs navigation, for example.

  FIG. 3 shows a conceptual diagram of navigation data stored in the recording medium 5. The navigation data has a data structure having “map data”, “highway route / fare data”, and “facility search data” as the highest hierarchy. In the “map data”, data relating to maps of all regions covered by the navigation data is managed. In the “highway route / charge data”, data related to the charges of all toll roads in the above-mentioned area are managed. In the “facility search data”, data of symbols that can be destinations such as restaurants, convenience stores, and stations in the region are managed. Note that the header of each hierarchy includes metadata relating to that hierarchy.

  Here, the lower hierarchy of “map data” will be described in detail. In the lower hierarchy of “map data”, there are “map division information data”, a plurality of “region data” (“region # 0 data”, “region # 1 data”, “region # 2 data”, etc. in FIG. 3). It is managed. “Map division information data” indicates how an area covered by the navigation data is divided and stored as data. In the “region data”, data on each divided region is managed.

  “Road data”, “background data”, and “character string data” are managed in a lower hierarchy of “regional data”. In the “road data”, data on roads included in the area is managed. In “background data”, map images of the terrain, buildings, roads, etc. in the area are managed. This map image is managed in association with a predetermined coordinate system, for example. In the “character string data”, text data representing names such as place names and facility names on the map is managed. These text data are also managed in association with the predetermined coordinate system.

  In the lower hierarchy of “road data”, “road data section” and “crossing prohibited line data section” are managed. In the lower hierarchy of the “road data section”, a plurality of road detailed data having detailed data of each road (“road # 0 data”, “road # 1 data”, “road # 2 data”, etc. in FIG. 3). Is managed. In each road detailed data, the road of the area currently treated as a single link is defined by the polyline, for example. That is, each road detailed data consists of a set of coordinates plotted on the road corresponding to the road detailed data in the map image. The “crossing prohibited line data section” manages detailed data on each crossing prohibited line (hereinafter referred to as “crossing prohibited line detailed data”). The “crossing prohibited line data section” will be described in detail later.

  Returning to the description of FIG. The input unit 6 is for performing a user operation, and is, for example, a mechanical input key installed on a front panel (not shown) of the navigation system 100. Alternatively, it is a remote control device (not shown) that realizes user operation by performing infrared communication with the user interface 14. For example, the power switch is one element constituting the input unit 6.

  The display unit 7 is for displaying a navigation screen, for example. An image displayed on the display unit 7 is generated by the image processing unit 15. In addition, the display unit 7 is a known touch panel such as a pressure-sensitive type or an electrostatic type, and also serves as an input unit. When the input unit 6 or the display unit 7 is operated, a signal corresponding thereto is input to the control unit 1 via the user interface 14. And the control part 1 controls each component so that the process corresponding to user operation may be performed.

  The ROM 8 stores programs and various data for realizing the navigation function. The DRAM 9 and the SRAM 10 are development destinations of programs and data stored in, for example, the recording medium 5 and the ROM 8. For example, the control unit 1 reads out a program stored in the recording medium 5 or the ROM 8 and develops the program in a predetermined area of the DRAM 9 or the SRAM 10 for execution. Thereby, for example, a navigation function is realized. The SRAM 10 is backed up by a battery when the power is turned off, and can retain the memory contents. The VRAM 11 is an image memory for holding an image displayed on the display unit 7.

  The FM signal processing unit 12 is an apparatus that receives, for example, FM multiplex broadcasting, extracts a desired signal from the received signal, and processes the extracted signal. The beacon processing unit 13 is a device that receives and processes a signal transmitted from, for example, an optical beacon installed on a main road or a radio beacon installed on an expressway. The signal received by the FM signal processing unit 12 or the beacon processing unit 13 is, for example, road traffic information (VICS (Vehicle Information and Communication System) signal) distributed by the road traffic information communication system center.

  Here, the processing of the control unit 1 when receiving the GPS positioning result from the GPS receiver 2 and the DR sensor output from each sensor will be described.

  The control unit 1 performs DR positioning calculation based on the DR sensor output output by each sensor, and obtains the traveling direction and the moving distance of the vehicle. Next, the control unit 1 compares the calculated DR positioning result and the GPS positioning result with the error estimation value for each positioning result. And based on this comparison result, the positioning result determined to be highly accurate is selected, and the selected positioning result is map-matched. Further, the control unit 1 extracts a map image around the current position from the navigation data of the recording medium 5 based on each positioning result. Next, the image processing unit 15 is operated so that the vehicle position mark indicating the current position of the vehicle is superimposed on the extracted map image. As a result, various information including navigation information is output and displayed on the display unit 7.

  The map matching here means correcting an error such as a vehicle position mark being displayed at a position off the road in the map displayed on the display unit 7. By performing map matching, the vehicle position can be matched with the map, and the user can accurately grasp the current position of the vehicle. Map matching is always performed regardless of the execution of navigation.

  Next, a road determination process for determining a departure road and a destination road, which is a process executed by the navigation system 100 of the present embodiment, will be described. FIG. 4 is a flowchart showing the road determination process.

  The flowchart shown in FIG. 4 is started when a user operation is performed such that a navigation function toward a desired destination is realized. That is, for example, when a destination name or the like is input and a search start operation is performed, the control unit 1 acquires the current position information of the vehicle using the DR positioning result, the GPS positioning result, and the like, and also obtains the navigation data. The information of the input destination is also acquired by referring to (step 1, abbreviated as “S” in the following specification and drawings). For convenience of explanation, “PP” is added to the current position acquired in the process of S1, and “T” is added to the destination.

  Next, the control unit 1 refers to the current position PP and reads “road data” of “region data” including the current position PP (S2). Then, with reference to the “crossing prohibited line data part” included in the “road data”, all crossing prohibited line detailed data included in the “crossing prohibited line data part” is extracted (S3).

  Here, the “crossing prohibition line data portion” will be described with reference to FIG. FIG. 5A shows a conceptual diagram of the “crossing prohibited line data portion”. The “crossing prohibited line data section” manages a plurality of detailed crossing prohibited line data (“crossing prohibited line # 0 data”, “crossing prohibited line # 1 data”, etc. in FIG. 5A). In the header, for example, the number of crossing prohibition line detailed data in its own lower hierarchy is described.

  Each crossing prohibition line detailed data is data for defining a boundary (hereinafter referred to as “crossing prohibition line”) between a place where the vehicle can pass and a place where the vehicle cannot pass. In addition, these crossing prohibition line detailed data are defined by defining, for example, the above crossing prohibition line with a polyline, similarly to the road detailed data described above. The control unit 1 recognizes that the vehicle cannot cross the crossing prohibited line defined by the crossing prohibited line detailed data. The crossing prohibition line is drawn on a map drawn based on “background data”, for example, along a river center line, along a lake coastline, along a coastline, or along a railway line that is not a three-dimensional intersection. It can also be drawn on a mountain ridgeline. Still further, it may be drawn to surround an impassable area in the mountains.

  For example, FIG. 5B shows a diagram for explaining the crossing prohibition line. According to the example of FIG. 5B, “crossing prohibited line # 0 data” and “crossing prohibited line # 1 data” are, for example, polylines drawn on a river drawn in “background data”. In other words, it is a polyline that defines a river. Since this river is on the crossing prohibition line defined by the crossing prohibition line detailed data, the control unit 1 can recognize that the vehicle cannot cross the river.

  Returning to the flowchart of FIG. After extracting the crossing prohibited line detailed data, the control unit 1 executes the processes of S4 to S7 for each road detailed data included in the “road data” read in the process of S2. In addition, the processing of S4 to S7 is performed in a predetermined order (for example, “road # 0 data”, “road # 1 data”, “road # 2 data”,...).

  In the process of S4, the control unit 1 calculates a nearest point An that is a point on the road defined by the detailed road data to be processed (hereinafter referred to as “processing target road”) and is closest to the current position PP. . The nearest point An is a point on the road that intersects the normal of the processing target road passing through the current position PP. At the same time as calculating the nearest point An, the control unit 1 makes a straight line LAn (that is, the normal line) connecting the current position PP and the nearest point An, and its straight line distance SAAn (distance between the current position PP and the nearest point An). Is calculated.

  Next, the control unit 1 determines whether or not the straight line distance SAn is shorter than the other straight line distances SAn already calculated in the current road determination process (S5). Here, when it is determined that the distance is other than the straight line distance SAn (S5: NO), the control unit 1 determines that the other road is more suitable as the starting road than the current processing target road, and the process of S8 is performed. Transition. On the other hand, when it determines with it being shorter than other linear distance SAn (S5: YES), the control part 1 judges that the present process target road can become a departure road, and transfers to the process of S6. Further, when the straight line distance is calculated for the first time in the process of S4 (that is, no straight line distance has been calculated), the control unit 1 determines “YES” in the process of S5 and proceeds to the process of S6. .

  In the process of S6, the control unit 1 refers to each crossing prohibition line detailed data extracted in the process of S3, and determines whether or not the straight line LAn intersects the crossing prohibition line defined by each crossing prohibition line detailed data. Determine whether. Here, when it is determined that there is a forbidden crossing line that intersects with the straight line LAn (S6: YES), the control unit 1 indicates that a crossing forbidden line exists between the current position PP and the current processing target road. Detecting and determining that the vehicle cannot be located on the road to be processed beyond the forbidden crossing line. Then, according to the determination result, the current processing target road cannot be a departure road, and the process proceeds to S8. On the other hand, when it is determined that the straight line LAn does not intersect any crossing prohibition line (S6: NO), the control unit 1 indicates that the vehicle is located on the current processing target road or the vehicle is present. It is determined that the processing target road is in a position where it can directly enter without passing through another road. Then, according to the determination result, the current processing target road is stored as a departure road candidate in, for example, the SRAM 10 (S7), and the process proceeds to S8. In the process of S7, when another road is held as a departure road candidate in the SRAM 10, the control unit 1 overwrites and saves the current road to be processed. For this reason, the candidate of the departure road currently hold | maintained at SRAM10 is always one.

  In the process of S8, the control unit 1 determines whether or not the processes of S4 to S7 have been executed for all the road detailed data included in the “road data” read in the process of S2. When it is determined in the process of S8 that there is road detailed data that has not been subjected to the processes of S4 to 7 (S8: NO), the control unit 1 returns to the process of S4 and performs the process for the next process target road. Execute. On the other hand, when it is determined in the process of S8 that the processes of S4 to S7 have been executed for all the road detailed data (S8: YES), the control unit 1 departs the candidate of the departure road held in the SRAM 10 The road is determined (S9). If there is no departure road candidate, the control unit 1 gradually expands the range for searching for the departure road until the candidate is found, for example. That is, the control unit 1 searches for a candidate for a departure road with reference to “road data” of other “region data” (that is, data other than “region data” including the current position PP). If there is no departure road candidate even if the search range is expanded to a predetermined level, the control unit 1 determines that there is an error, for example, and ends the process of this flowchart.

  Next, the control unit 1 performs a process for determining a destination road. First, the control unit 1 refers to the destination T and reads “road data” of “region data” including the destination T (S10). Then, referring to the “crossing prohibited line data part” included in the “road data”, all the crossing prohibited line detailed data included in the “crossing prohibited line data part” is extracted (S11).

  After extracting the crossing prohibited line detailed data, the control unit 1 executes the processes of S12 to S15 for each of the road detailed data included in the “road data” read in the process of S10. In addition, the processing of S12 to S15 is performed in a predetermined order (for example, “crossing prohibited line # 0 data”, “crossing prohibited line # 1 data”,...).

  In the process of S12, the control unit 1 calculates a nearest point Bn that is a point on the processing target road and is closest to the destination T. This nearest neighbor point Bn is a point on the road that intersects the normal line of the processing target road passing through the destination T. At the same time as calculating the nearest point Bn, the control unit 1 makes a straight line LBn (that is, the normal line) connecting the destination T and the nearest point Bn, and its length SBn (distance between the destination T and the nearest point Bn). Is calculated.

  Next, the control unit 1 determines whether or not the straight line distance SBn is shorter than another straight line distance SBn that has already been calculated in the current road determination process (S13). Here, when it is determined that the distance is equal to or longer than the other straight distance SBn (S13: NO), the control unit 1 determines that the other road is more suitable as the destination road than the current processing target road, and performs the process of S16. Transition. On the other hand, when it determines with it being shorter than other linear distance SBn (S13: YES), the control part 1 judges that the present process target road can become a destination road, and transfers to the process of S14. Further, when the calculation of the straight line distance in the process of S12 is the first time (that is, no straight line distance has been calculated), the control unit 1 determines “YES” in the process of S13 and proceeds to the process of S14. .

  In the process of S14, the control unit 1 refers to each crossing prohibition line detailed data extracted in the process of S11, and determines whether or not the straight line LBn intersects the crossing prohibition line defined by each crossing prohibition line detailed data. Determine whether. Here, when it is determined that there is a crossing prohibited line that intersects with the straight line LBn (S14: YES), the control unit 1 determines that a crossing prohibited line exists between the destination T and the current processing target road. It is determined that the vehicle cannot reach the processing target road immediately beyond the forbidden crossing line. Then, according to this determination result, it is determined that the current processing target road is inappropriate as the destination road, and the process proceeds to S16. On the other hand, when it is determined that the straight line LBn does not intersect any crossing prohibition line (S14: NO), the control unit 1 indicates that the current processing target road is in the vicinity of the destination T and the river is in the meantime. It is judged that there are no obstruction factors such as. Then, according to the determination result, the current processing target road is stored as a destination road candidate in, for example, the SRAM 10 (S15), and the process proceeds to S16. In the process of S15, when another road is held as a destination road candidate in the SRAM 10, the control unit 1 overwrites and saves the current process target road. For this reason, there is always one destination road candidate held in the SRAM 10.

  In the process of S16, the control unit 1 determines whether or not the processes of S12 to S15 have been executed for all the road detailed data included in the “road data” read in the process of S10. When it is determined in the process of S16 that there is road detailed data that has not been subjected to the processes of S12 to 15 (S16: NO), the control unit 1 returns to the process of S12 and performs the process for the next process target road. Execute. On the other hand, when it is determined in the process of S16 that the processes of S12 to S15 have been executed for all the road detailed data (S16: YES), the control unit 1 sets the target road candidates held in the SRAM 10 as the target. The road is determined (S17). As a result, the departure road and the destination road are determined, and the processing of this flowchart ends. When there is no destination road candidate, the control unit 1 gradually expands the range for searching for the destination road until the candidate is found, for example. That is, the control unit 1 searches for destination road candidates with reference to “road data” of other “region data” (that is, data other than “region data” including the destination T). If there is no destination road candidate even if the search range is expanded to a predetermined level, the control unit 1 determines, for example, an error and ends the processing of this flowchart.

When the processing of the flowchart of FIG. 4 is completed, the control unit 1 executes a search for a route using the nearest neighbor point An on the confirmed departure road as the start point and the nearest neighbor point Bn on the destination road as the end point using the Dijkstra method. . Thus even in a situation where the starting location of the vehicle is shown in FIG. 1, for example, the route search that starting from the point S ₂ instead of the point S ₁ is executed. That is, a point closest to the current position PP on a road where no crossing prohibition line exists between the current position PP and the current position PP is set as the starting point of the route. The same applies to the end point. That is, the point closest to the destination T on the road where there is no crossing prohibition line with the destination T is set as the end point of the route. That is, according to this embodiment, the departure road and the destination road are reachable and are determined as more appropriate roads. In addition, according to the navigation system 100 of the present embodiment, the road having the highest possibility of entering the vehicle after departure is set as the departure road. Further, the road that is most likely to travel last when the vehicle reaches the destination is set as the destination road. As a result, the start point and end point of the route become more accurate, and accordingly, the route obtained by the search can also become more accurate.

  The above is the embodiment of the present invention. The present invention is not limited to these embodiments and can be modified in various ranges.

It is a figure which shows the positional relationship of a vehicle, each road, a river, etc. It is the block diagram which showed the structure of the navigation system of embodiment of this invention. The conceptual diagram of the navigation data stored in the recording medium of embodiment of this invention is shown. It is the flowchart which showed the road determination process performed in embodiment of this invention. It is a figure for demonstrating the crossing prohibition line of embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control part 2 GPS receiver 3 Gyro sensor 4 Vehicle speed sensor 5 Recording medium 6 Input part 7 Display part 8 ROM
9 DRAM
10 SRAM
11 VRAM
12 FM signal processing unit 13 Beacon processing unit 14 User interface 15 Image processing unit 100 Navigation system

Claims (9)

In a navigation system that performs route search with reference to predetermined map data,
A first road acquisition means for searching the map data using information representing a departure place, and obtaining at least one road information around the departure place;
First distance calculation means for calculating a distance between the starting point and the nearest point that is a distance on the map data and is a point on the road acquired by the first road acquiring means. When,
First road determination means for determining whether or not there is a place where the vehicle cannot pass on a straight line connecting the starting point and the closest point on the map data;
A navigation system, comprising: a departure road determination unit that determines a departure road based on a calculation result by the first distance calculation unit and a determination result by the first road determination unit.   The departure road determining means determines a road closest to the departure place as a departure road among roads where there is no place that prevents vehicle traffic between the departure place and the closest point. The navigation system according to claim 1. Destination acquisition means for acquiring destination information set by a predetermined user operation;
Second road acquisition means for searching the map data using information on the destination acquired by the destination acquisition means, and acquiring at least one road information around the destination;
Second distance calculating means for calculating a distance between the road acquired by the second road acquiring means and the destination, which is a distance on the map data;
Second road determination means for determining whether or not the destination can be reached from the road without passing through another road on the map data;
The destination road determining means for determining the destination road based on the calculation result by the second distance calculation means and the determination result by the second road determination means, further comprising: Item 3. The navigation system according to any one of Items 2 to 3.   The said destination road determination means determines the road nearest to the said destination as the destination road among the roads which can reach this destination without passing through another road, The destination road is characterized by the above-mentioned. Navigation system. In a road determination method for determining a departure road when searching for a route with reference to predetermined map data,
A first road acquisition step of searching the map data using information representing a departure place, and obtaining at least one road information around the departure place;
A first distance calculating step of calculating a distance between the starting point and the closest point closest to the starting point which is a distance on the map data, which is a point on the road acquired by the first road acquiring step When,
A first road determination step for determining whether or not there is a place where the vehicle cannot pass on a straight line connecting the starting point and the closest point on the map data;
A road determination method, comprising: a departure road determination step for determining a departure road based on a calculation result of the first distance calculation step and a determination result of the first road determination step.   In the departure road determination step, a road closest to the departure place is determined as a departure road among roads where there is no place that prevents vehicle traffic between the departure place and the closest point. The road determination method according to claim 5. A destination acquisition step of acquiring destination information set by a predetermined user operation;
A second road acquisition step of searching the map data using the destination information acquired by the destination acquisition step, and acquiring at least one road information around the destination;
A second distance calculating step for calculating a distance between the road acquired by the second road acquiring step and the destination, which is a distance on the map data;
A second road determination step for determining whether or not the destination can be reached from the road without passing through another road on the map data;
6. The destination road determination step of further determining a destination road based on the calculation result of the second distance calculation step and the determination result of the second road determination step. The road determination method according to any one of 6.   8. The destination road determining step, wherein a road closest to the destination is determined as a destination road among roads that can reach the destination without passing through another road. Road decision method. A map data structure for causing a computer to determine a departure road and a destination road for route search,
A map image associated with a predetermined coordinate system and including at least a road and terrain,
Define the road with a first polyline corresponding to the coordinate system,
Furthermore, in order to make the computer recognize a place where the vehicle cannot pass, the map data is characterized in that a boundary between a place where the vehicle can pass and a place where the vehicle cannot pass is defined by a second polyline corresponding to the coordinate system. Construction.

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