WO2004111972A1 - Method and system for finding path for navigation service - Google Patents

Method and system for finding path for navigation service Download PDF

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Publication number
WO2004111972A1
WO2004111972A1 PCT/KR2003/002221 KR0302221W WO2004111972A1 WO 2004111972 A1 WO2004111972 A1 WO 2004111972A1 KR 0302221 W KR0302221 W KR 0302221W WO 2004111972 A1 WO2004111972 A1 WO 2004111972A1
Authority
WO
WIPO (PCT)
Prior art keywords
path
predetermined
searching
road information
destination
Prior art date
Application number
PCT/KR2003/002221
Other languages
French (fr)
Inventor
Jin Beom Kim
Hee Back Lee
Original Assignee
Thinkware Systems Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thinkware Systems Corporation filed Critical Thinkware Systems Corporation
Priority to JP2005500790A priority Critical patent/JP2006527837A/en
Priority to AU2003273090A priority patent/AU2003273090A1/en
Publication of WO2004111972A1 publication Critical patent/WO2004111972A1/en

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/09—Arrangements for giving variable traffic instructions
    • G08G1/0962—Arrangements for giving variable traffic instructions having an indicator mounted inside the vehicle, e.g. giving voice messages
    • G08G1/0968—Systems involving transmission of navigation instructions to the vehicle
    • G08G1/096833—Systems involving transmission of navigation instructions to the vehicle where different aspects are considered when computing the route
    • G08G1/096838—Systems involving transmission of navigation instructions to the vehicle where different aspects are considered when computing the route where the user preferences are taken into account or the user selects one route out of a plurality
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B9/00—Steam boilers of fire-tube type, i.e. the flue gas from a combustion chamber outside the boiler body flowing through tubes built-in in the boiler body
    • F22B9/10—Steam boilers of fire-tube type, i.e. the flue gas from a combustion chamber outside the boiler body flowing through tubes built-in in the boiler body the boiler body being disposed substantially horizontally, e.g. at the side of the combustion chamber
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B37/00—Component parts or details of steam boilers
    • F22B37/02—Component parts or details of steam boilers applicable to more than one kind or type of steam boiler
    • F22B37/40—Arrangements of partition walls in flues of steam boilers, e.g. built-up from baffles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F22—STEAM GENERATION
    • F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
    • F22B9/00—Steam boilers of fire-tube type, i.e. the flue gas from a combustion chamber outside the boiler body flowing through tubes built-in in the boiler body
    • F22B9/18—Component parts thereof; Accessories therefor, e.g. stay-bolt connections
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
    • G01C21/26—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 specially adapted for navigation in a road network
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/09—Arrangements for giving variable traffic instructions
    • G08G1/0962—Arrangements for giving variable traffic instructions having an indicator mounted inside the vehicle, e.g. giving voice messages
    • G08G1/0968—Systems involving transmission of navigation instructions to the vehicle
    • G08G1/096833—Systems involving transmission of navigation instructions to the vehicle where different aspects are considered when computing the route
    • G08G1/096844—Systems involving transmission of navigation instructions to the vehicle where different aspects are considered when computing the route where the complete route is dynamically recomputed based on new data
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/09—Arrangements for giving variable traffic instructions
    • G08G1/0962—Arrangements for giving variable traffic instructions having an indicator mounted inside the vehicle, e.g. giving voice messages
    • G08G1/0968—Systems involving transmission of navigation instructions to the vehicle
    • G08G1/096877—Systems involving transmission of navigation instructions to the vehicle where the input to the navigation device is provided by a suitable I/O arrangement
    • G08G1/096883—Systems involving transmission of navigation instructions to the vehicle where the input to the navigation device is provided by a suitable I/O arrangement where input information is obtained using a mobile device, e.g. a mobile phone, a PDA
    • G—PHYSICS
    • G08—SIGNALLING
    • G08G—TRAFFIC CONTROL SYSTEMS
    • G08G1/00—Traffic control systems for road vehicles
    • G08G1/09—Arrangements for giving variable traffic instructions
    • G08G1/0962—Arrangements for giving variable traffic instructions having an indicator mounted inside the vehicle, e.g. giving voice messages
    • G08G1/0968—Systems involving transmission of navigation instructions to the vehicle
    • G08G1/096877—Systems involving transmission of navigation instructions to the vehicle where the input to the navigation device is provided by a suitable I/O arrangement
    • G08G1/096894—Systems involving transmission of navigation instructions to the vehicle where the input to the navigation device is provided by a suitable I/O arrangement where input is assisted by the navigation device, i.e. the user does not type the complete name of the destination, e.g. using zip codes, telephone numbers, progressively selecting from initial letters

Definitions

  • the present invention relates to a method and system for searching a path, and more particularly, to a method and system for searching a path capable of reducing time and load of the system taken to search a path based on road information by using layers associated with the road information.
  • a navigation system is a system that provides traffic information to vehicles such as automobiles using an artificial satellite and is also referred to as an automatic navigation system.
  • a navigation system receives predetermined data from Global Positioning System (GPS) satellites orbiting the earth using a GPS receiver and calculates its own position based on the received data.
  • GPS Global Positioning System
  • a navigation system can receive GPS signals from three GPS satellites no matter where the vehicle is located on the earth and calculate its own position based on the GPS signals received from the three GPS satellites.
  • the navigation system provides a variety of traffic information to vehicles such automobiles based on the information on its own position calculated as such.
  • the navigation system provides a user with a variety of information including the current position information of a vehicle, routing information from the current position to the destination of a vehicle, map information related to the position and routing information, traffic information and the like. Since using a map allows the user to easily understand the information on the current position and the like when the user receives the current position and other information from the navigation system, the map information is generally provided to the user together with the current position information and the like.
  • map information has been provided to a user via a storage medium such as CD ROM or DVD ROM.
  • a storage medium such as CD ROM or DVD ROM.
  • Such a conventional navigation system reads, if necessary, the map information stored in the storage medium such as CD ROM and then displays the read information on a predetermined display means.
  • the storage medium itself such as CD ROM should be replaced, and thus, this is very troublesome whenever the map information is updated later on. In other words, financial and time losses occur because the user should continue to purchase the CD ROM containing updated map information from a CD ROM provider.
  • the updated map information (for example, when roads, buildings and the like are newly created or destroyed) cannot be provided to the user in real time.
  • navigation services using mobile devices such as mobile phones have been provided.
  • the telematics services can guide a user to a destination using voice data.
  • the telematics services automatically track the position of the accident car using GPS satellites and transmit the information on the position of the accident car to rescue services, hospitals or the like that are located nearest to the position of the accident, so that rescue activities can be promptly performed.
  • a navigation system that can reflect updated map information related to roads, etc. in real time by providing the map information to a mobile device via a communication network.
  • map information is provided to the mobile device via a wireless communication network, it is an important issue to reduce the time taken in providing a map in order to provide the mobile device with map information in real time.
  • one of main services required by users is to provide path information obtained as a result of a path search.
  • the path search generally includes the steps of calculating a plurality of paths from a source to a destination based on map information stored in a predetermined numerical map database and then selecting an appropriate path (for example, the shortest path) from the calculated paths. At this time, since there are usually a plurality of paths from the source to the destination, some time is required to calculate the plurality of the paths until the appropriate path is selected. Such calculation of the path may cause a time delay or load in a predetermined system for searching a path until the result of the path search is provided to the mobile device.
  • path information and map information are received from a predetermined map providing server via a wireless communication network
  • the above method may be needed for the same reason even in a case where map information is provided from a predetermined map providing server via a wired communication network without providing map information through a wireless communication network as in the prior art, or a case where a path is searched in a user terminal by using map information stored in a recording medium.
  • An object of the present invention is to provide a method and system for searching a path capable of reducing time taken to search a path based on predetermined road information and reducing load in a system for searching the path.
  • a method for searching a path comprising the steps of maintaining road information corresponding to roads and layers which are associated with the road information and determined according to a predetermined criterion, in a predetermined numerical map database; searching a first path within a predetermined first distance from a source based on the road information associated with a predetermined first layer set including the one or more layers; searching a second path from the source from the predetermined first distance from a destination to a predetermined second distance based on the road information associated with a predetermined second layer set including the one or more layers; searching a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers; and generating a path from the source to the destination by using the first path, the second path, and the third path.
  • a method for searching a path of the present invention further comprises the steps of receiving the source and the destination from a user's mobile device, and transmitting the generated path to the mobile device.
  • a system for searching a path of the present invention performs the steps of receiving a current position of the mobile device from a GPS receiver of the mobile device; determining whether the mobile device deviates from the transmitted path based on the transmitted path and the current position; and if the user deviates from the transmitted path, setting the current position as the source.
  • a method for searching a path of the present invention may further comprise the steps of receiving a current position of the mobile device from a GPS receiver of the mobile device; determining whether the mobile device deviates from the transmitted path based on the transmitted path and the current position; and if the user deviates from the transmitted path, setting the current position as a source.
  • a method for searching a path which comprises the steps of maintaining road information in a predetermined numerical map database; calculating one or more first candidate paths from a source to a destination based on the road information; determining, as a second candidate path, a predetermined number of first candidate paths that reach a critical point located at a certain distance away from the destination, among the first candidate paths; stopping calculation of the first candidate paths that are not determined as the second candidate path; calculating the second candidate path from the critical point to the destination; and determining the second candidate path for which the calculation is completed as a path.
  • a system for searching a path which comprises a numerical map database for maintaining road information corresponding to roads and layers which are associated with the road information and determined according to a predetermined criterion; a user receiving unit for receiving a source and destination from a mobile device of a user; a path search unit for searching a path from the source to the destination based on the road information; and a user transmission unit for transmitting the searched path to the mobile device, wherein the path search unit is configured to search a first path within a predetermined first distance from the source based on the road information associated with a predetermined first layer set including one or more layers, to search a second path from the source from the predetermined first distance from a destination to a predetermined second distance based on the road information associated with a predetermined second layer set including the one or more layers, to search a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers, and to generate a
  • FIG. 1 is a flowchart illustrating the steps for embodying a method for searching a path according to an embodiment of the present invention.
  • FIG. 2 shows a network configuration of a system for searching a path that performs a method for searching a path according to an embodiment of the present invention.
  • FIG. 3 is a view illustrating an example of road information, in a method for searching a path according to an embodiment of the present invention.
  • FIG. 4 is a view illustrating an example of road information maintained in a numerical map database and layers associated with the road information, in a method for searching a path according to an embodiment of the present invention.
  • FIG. 5 is a view illustrating a case where a layer for a predetermined road is determined so as to secure the integrity of path search information, in a method for searching a path according to an embodiment of the present invention.
  • FIG. 6 (a) to (f) are views illustrating examples of input windows for inputting a source and destination, which are provided in a user's mobile device
  • FIG. 6 (g) to (i) are views illustrating paths displayed in the mobile device, in the method for searching a path according to an embodiment of the present invention.
  • FIG. 7 is a view illustrating a method for searching a path according to an embodiment of the present invention.
  • FIG. 8 is a view illustrating a path searched based on road information associated with first to third layer sets, in a method for searching a path according to an embodiment of the present invention.
  • FIG. 9 is a flowchart illustrating the steps for embodying a method for searching a path according to another embodiment of the present invention.
  • FIG. 10 is a view illustrating a method for searching a path according to another embodiment of the present invention.
  • FIG. 11 is a block diagram showing the configuration of a system for searching a path according to another embodiment of the present invention.
  • FIG. 12 is an inner block diagram showing a typical computer system in accordance with an embodiment of the present invention.
  • FIG. 1 is a flowchart illustrating the steps for embodying a method for searching a path according to an embodiment of the present invention.
  • the method for searching a path according to this embodiment can be performed in a predetermined system for searching a path.
  • FIG. 2 shows the network configuration of a system for searching a path that performs the method for searching a path according to an embodiment of the present invention.
  • Reference numeral 210 indicates a system for searching a path and reference numeral 230 indicates a mobile device connected to the system for searching a path 210 via a communication network 220.
  • the system for searching a path 210 searches a path corresponding to a predetermined source and destination and then provides the searched path to the mobile device 230.
  • the system for searching a path 210 maintains road information and layers, which are associated with the road information and determined according to a predetermined criterion, in a predetermined numerical map database (SlOl).
  • the road information is data for specifying the road on a map and may be defined in various modes.
  • FIG. 3 is a view for explaining exemplary road information.
  • the road information includes a node, a link and an interpolation point. Dark points as indicated by Nl designate nodes, and lines for connecting the nodes as indicated by Ll 3 L2 and L3 designate links.
  • the node is information for indicating an intersecting point where roads cross or a dead place on a road, and the link provides information for indicating roads between the nodes.
  • interpolation points provide information for indicating points, on a curved road, through which the road passes.
  • a greater number of interpolation points are required in order to display the road.
  • road information corresponding to a road can be defined.
  • road information may be defined in a variety of manners.
  • FIG. 4 shows exemplary road information and layers associated with the road information, which are maintained in a numerical map database.
  • the layer associated with the road information is determined on the basis of one or more road types, the traffic of vehicles using the road and the number of lanes.
  • a layer associated with an express highway or an urbanized express highway may be determined as layer 2
  • a layer associated with common roads or civil roads may be determined as layer 3.
  • a national road of 4 or more lanes may be defined as layer 3 and a provincial road of 4 or less lanes may be defined as layer 4.
  • a layer for a regional road having a high coefficient of utilization i.e. a provincial road having a lot of traffic, may be defined as layer 3.
  • the average value of vehicles that employ the provincial road a day, the average value of vehicles that employ the provincial road in a specific time interval, or the like is calculated and is then reflected to determine layer. If the average value in a specific time interval is used, a search may be performed based on different layers depending on the time interval where users request paths, in a state where each layer in each time interval for single road information is maintained.
  • a layer associated with a road can be determined based on the type of road.
  • the layer may be changed according to a variety of criteria. Further, the layer may be determined in order to secure the integrity of "path search information".
  • FIG. 5 is a view for explaining a case where a layer for a predetermined road is determined so as to secure the integrity of path search information.
  • the system for searching a path 210 searches a path based on road information associated with a predetermined layer set. Therefore, road information associated with layers included in the layer set is used as material for a path search, but road information associated with layers not included in the layer set is not used as material for the path search.
  • a certain road may consist of four lanes except for some sections that are two lanes.
  • respective links indicated by reference numerals L521 to L523 are classified by respective nodes, which are indicated by reference numerals N511 and N512.
  • layer 3 is maintained in the numerical map database
  • layer 4 is maintained in the numerical map database.
  • the system for searching a path 210 searches a path based on only road information associated with a layer set including only the layer 3 not the layer 4, the road (corresponding to the links L521 to L523 among road information) corresponds to a case where a road portion corresponding to the link L523 does not exist. Accordingly, there is a problem in that a path from the link L521 to a road corresponding to the link L522 is not searched. Therefore, in such a case, even when the type of road or the number of lanes differs, a layer associated with the link L523 needs to be set as layer 3 like the layer associated with the links L521 and L522.
  • layer 2 layer 3 and the like are used to identify respective layers. Modes for storage and representing each layer may be quite different from the above case.
  • the system for searching a path 210 receives a source and destination from a user's mobile device 230 via the communication network 220 (S102).
  • FIG. 6 (a) to (f) illustrate exemplary input windows for inputting source and destination information, which are provided in the mobile device 230.
  • the user selects "Guide New Road", which is a menu provided for a path search.
  • "Name Search” for example, "Seoul City Hall”
  • an "Address Search” for example, "142, Nonhyun-Dong'
  • FIG. 6 (b) the system for searching a path 210 provides one or more methods for allowing the user to input a source and destination.
  • FIG. 6 (c) if the user inputs
  • the system for searching a path 210 further provides a function of setting a transit point.
  • the user can select a transit point, as shown in FIG. 6 (e). If the transit point is input, the system for searching a path 210 searches a path through the transit point among a path from the source to the destination and then provides the searched path to the user.
  • FIG. 6 (f) shows an input window for allowing the user to input a source.
  • FIG. 6 (f) shows a case where the current position of the mobile device 230 (corresponding to a current position of the mobile device 230 received by a GPS receiver associated with the mobile device 230) is set as a source, the same method as the method for inputting the aforementioned destination can be used even in case of a source.
  • the system for searching a path 210 searches a path from the source to the destination (S 103 to S 105), if the source and destination are input by the mobile device 230.
  • an area within a predetermined first distance dl from the source is defined as a first area
  • an area within a predetermined second distance d2 from the destination is defined as a third area
  • areas other than the first and third areas are defined as a second area.
  • the system for searching a path 210 searches a path from the source based on the road information associated with a predetermined first layer set including one or more layers, which are maintained in the numerical map database, in the first area (S103).
  • the system for searching a path 210 searches a second path based on the road information associated with a second layer set including one or more layers in the second area (S 104).
  • the system for searching a path 210 searches a third path up to the destination based on the road information associated with a predetermined third layer set including one or more layers in the third area (S 105).
  • a path is searched based on all or most road information in an area around a source and destination.
  • a path is searched based on road information corresponding to an express highway, a national road and so on in the remaining areas. For example, if a user requests a path from "Seoul City Hall" to "Sasang-Gu
  • the first layer set and the third layer set are set to include a large number of layers.
  • a path that is same as or similar to a path obtained based on all the road information containing residential streets in addition to main roads, etc. around the source and destination is provided to a user.
  • the second layer set is set to include a layer associated with road information corresponding to an express highway, main roads and the like. Consequently, it is possible to reduce the amount of calculation in the system for searching a path 210, while providing substantially the same path as a case where paths for the entire areas are searched based on the whole road information.
  • the values of the first and second distance dl and d2 may be the ⁇ same as or different from each other.
  • the first and second distances dl and d2 are values input from the mobile device 230.
  • a user may input the dl as a small value regarding to the vicinity of a source that the user knows well its geographical features, whereas he/she may input the d2 as large value regarding a destination that the user knows little about its geographical features. By doing so, the user can receive a detailed path even for an area that is away from the destination.
  • the first and second distances may be distances that are set by an operator of the system for searching a path 210.
  • the user may select one of what the system for searching a path 210 automatically sets the first and second distances and what the user directly inputs the first and second distances.
  • the first layer set or the third layer set contains all the layers maintained in the numerical map database.
  • FIG. 8 is a view for explaining a path searched based on road information associated with the first to third layer sets.
  • FIG. 8 (a) shows the vicinity of "Seoul City
  • FIG. 8 (b) shows the vicinity of "Sasang-Gu Office" being a destination.
  • FIG. 8 (a) and (b) show a case where the first and third layer sets include all the sets of layers. Therefore, the system for searching a path 210 searches a path by using the whole road information (each node, link and interpolation point) in first and third areas.
  • FIG. 8 (c) and (d) show the second areas between the source and the destination.
  • the system for searching a path 210 searches a path by using only road information on main roads, which appear to be highly used by users.
  • the system for searching a path 210 generates a path from the source ("Seoul City Hall”) to the destination ("Sasang-Gu Office") by using the first to third paths obtained by performing the steps S 103 to S 105 (S 106).
  • FIG. 6 (g) shows a map displayed in the mobile device 230 during the transmission time taken until when the system for searching a path 210 transmits the path to the mobile device 230.
  • the transmission time is significantly reduced compared to the prior art.
  • the width of the area reduced becomes increasingly large as an area to be searched becomes wider.
  • the user of the mobile device 230 may be provided with a requested path.
  • a variety of services associated with a path search such as "Simulation Driving”, “View Driving Path”, “Destination Information” and “Reset Path” may be provided to a user.
  • Such services may be performed by receiving predetermined data from the system for searching a path 210 or may be performed in the mobile device 230 such as "View Driving Path” and the like.
  • the system for searching a path 210 performs steps (S 108 to Sl 10) in preparation for a case where the user deviates from the transmitted path without moving along the path.
  • the system for searching a path 210 receives the current position of the mobile device 230 from the mobile device 230 (S108).
  • the current position may be obtained from a GPS receiver associated with the mobile device 230.
  • the GPS receiver may be built in the mobile device 230 or may be separately installed so as to transmit predetermined information to the mobile device 230.
  • the system for searching a path 210 frequently receives the current position of the mobile device 230 from the GPS receiver and determines whether the mobile device 230 deviates from the path based on the current position (S 109). According to another embodiment of the present invention, the system for searching a path 210 determines "Deviation of Path" when the mobile device 230 deviates from the path by a predetermined distance in a straight distance. Furthermore, a variety of decision methods using the current position may be employed.
  • FIG. 9 is a flowchart illustrating the steps for embodying a method for searching a path according to another embodiment of the present invention. As in the aforementioned embodiment, this method may be performed in a predetermined system for searching a path. The method for searching a path according to this embodiment will now be described with reference to FIG. 10.
  • the system for searching a path has road information maintained in a predetermined numerical map database (S901), and calculates one or more first candidate paths from a source to a destination based on the road information (S902).
  • the source and destination are data input by a user using a mobile device.
  • the number of paths from the source to the destination may be only one, the number of paths is usually plural, including a path corresponding to the shortest distance. For this reason, a number of first candidate paths are calculated in step S902.
  • the system for searching a path determines, as a second candidate path, a predetermined number of first candidate paths that reached a critical point located at a certain distance (d3 in FIG. 10) from the destination among the first candidate paths (S903).
  • a critical point is a point located on a circle indicated by dotted lines in FIG. 10.
  • the system for searching a path can solve an error problem with an actual distance due to error, etc. on map information, by determining whether the user reaches a critical point within an error range.
  • the system for searching a path determines the critical point from a point, which is away from the destination by 1.98 km, to a point, which is away from the destination by 2.02 km.
  • the system for searching a path stops calculating the first candidate paths that are not determined as the first candidate path (S904) and calculates the second candidate path from the critical point to the destination (S905).
  • the first candidate path that is determined as the second candidate path in step (S903) may be 1 or more in number.
  • the system for searching a path may stop calculation for the remaining first candidate paths if there is a first candidate path that reaches the critical point at the fastest time. If the certain number is set to 2, the system for searching a path may stop calculation for the first candidate paths except for a first candidate path that reaches the critical point at the fastest time and a first candidate path that reaches the critical point at the second fastest time.
  • a path from a source to a destination is calculated without stopping calculating the path. If a path up to the destination is completely calculated for the second candidate path, the system for searching a path determines the second candidate path as "Path" (S906). The determined path may be then provided to the user.
  • first candidate paths from a source to a destination may be plural in nature.
  • Most of the paths are ones not selected according to a predetermined criterion and by the system for searching a path.
  • the predetermined criterion may include various factors such as total length of the path, the number of lanes corresponding to the path and the like.
  • the system for searching a path may select a path that will be provided to a user in various manners such as selecting a path whose total length is simply the shortest, or a path whose total length is the shortest among paths having the number of 2 or more lanes corresponding to a path.
  • a second candidate path for which a path up to the vicinity of the destination is completely calculate is usually determined as a path.
  • To continue to calculate the remaining first candidate paths may cause the load of the system for searching a path to increase and the time until the completion of a path search to be delayed.
  • the computer-readable recording medium may contain program instructions, data files, data structures, or a combination thereof.
  • the program instructions may be ones that are specially designed or written for the present invention or may be ones that are well known to those skilled in the field of computer software.
  • the computer-readable recording medium includes a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, an optical medium such as CD-ROM and DVD, a magneto-optical medium such as a floptical disk, and hardware devices such as read only memory (ROM), random access memory (RAM) and flash memory that are specially configured to store and execute the program instructions.
  • the medium may be a transfer medium such as an optical or metal line and waveguide, including a carrier wave that transmits signals for specifying the program instructions, data structures and the like.
  • Examples of the program instructions may include high-level language codes executable by a computer using an interpreter as well as machine language codes such as those written by a compiler.
  • FIG. 11 is a block diagram illustrating the configuration of a system for searching a path according to another embodiment of the present invention.
  • a numerical map database 1101 stores therein road information and layers that are associated with the road information and determined according to a predetermined criterion.
  • a receiving unit 1102 receives a source and destination from a user's mobile device 1110 via a communication network 1120.
  • a path search unit 1103 searches a path up to the destination based on the road information.
  • a transmission unit 1104 transmits the searched path to the mobile device 1110 via the communication network
  • the path search unit 1103 searches a first path within a predetermined first distance from a source based on the road information associated with a predetermined first layer set including one or more layers, searches a second path from the predetermined first distance away from the source to a predetermined second distance away from the destination based on the road information associated with a predetermined second layer set including the one or more layers, searches a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers, and generates a path from the source to the destination by using the first path, the second path and the third path.
  • the first and third layer sets, the first and second distances, and a path search and generating process in the path search unit 1103 are same as those described with reference to the aforementioned embodiment. Therefore, detailed explanation on them will be omitted for simplicity.
  • FIG. 12 shows an inner block diagram of a typical computer system in accordance with an embodiment of the present invention.
  • the computer system 1200 includes any number of processors 1201 (also referred to as central processing units, or CPUs) that are coupled to storage devices including primary storage 1202 (typically a random access memory, or "RAM"), primary storage 1203 (typically a read only memory, or "ROM").
  • primary storage 1202 typically a random access memory, or "RAM”
  • primary storage 1203 typically a read only memory, or "ROM”
  • primary storage 1203 acts to transfer data and instructions uni-directionally to the CPU and primary storage 1202 is used typically to transfer data and instructions in a bi-directional manner. Both of these primary storage devices may include any suitable type of the computer-readable media described above.
  • a mass storage device 1204 is also coupled bi-directionally to CPU 1201 and provides additional data storage capacity and may include any of the computer-readable media described above.
  • the mass storage device 1204 may be used to store programs, data and the like and is typically a
  • processor 1201 is also coupled to an interface 1205 that includes one or more input/output devices such as such as video monitors, track balls, mice, keyboards, microphones, touch-sensitive displays, transducer card readers, magnetic or paper tape readers, tablets, styluses, voice or handwriting recognizers, or other well-known input devices such as, of course, other computers.
  • processor 1201 optionally may be coupled to a computer or telecommunications network using a network connection as shown generally at 1207.
  • the CPU might receive information from the network, or might output information to the network in the course of performing the above-described method steps.
  • the above-described devices and materials will be familiar to those of skill in the computer hardware and software arts.
  • the hardware elements described above may be configured (usually temporarily) to act as one or more software modules for performing the operations of this invention.
  • a path that is the same as or similar to a case where a path is searched based on the entire road information is provided to a user. Furthermore, it is possible to reduce the time needed for a path search and load in a system for searching a path that performs the path search. As such, as the time needed for the path search is shortened, the time from when a user requests a path search to when the user receives the requested path is shortened.
  • a path if the user deviates from the path, a current position of the user is set as a source and a new path is provided to the user.
  • calculation for candidate paths except for candidate paths having a high possibility that will be selected as a path is stopped before its calculation is completed. It is therefore possible to reduce the time needed for a path search and load in a system for searching a path.

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Abstract

The present invention relates to a method and system for searching a path, and more particularly, to a method and system for searching a path capable of reducing time and load of the system taken to search a path based on road information by using layers associated with the road information A method for searching a path according to the present invention comprising the steps of maintaining road information corresponding to roads and layers which are associated with the road information and determined according to a predetermined criterion, in a predetermined numerical map database; searching a first path within a predetermined first distance from a source based on the road information associated with a predetermined first layer set including the one or more layers; searching a second path from the source from the predetermined first distance from a destination to a predetermined second distance based on the road information associated with a predetermined second layer set including the one or more layers; searching a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers; and generating a path from the source to the destination by using the first path, the second path, and the third path. According to the present invention, it is possible to reduce the time needed for a path search based on road information and load in a system for a path search.

Description

Method and System for Finding Path for Navigation Service
Technical Field
The present invention relates to a method and system for searching a path, and more particularly, to a method and system for searching a path capable of reducing time and load of the system taken to search a path based on road information by using layers associated with the road information.
Background Art Recently, due to the provision of services through communication networks, opportunities to search information in a wireless communication environment such as portable computers and mobile phones have increased. Thus, a user can search desired information and obtain desired services anywhere or anytime while freely moving.
A navigation system is a system that provides traffic information to vehicles such as automobiles using an artificial satellite and is also referred to as an automatic navigation system. Such a navigation system receives predetermined data from Global Positioning System (GPS) satellites orbiting the earth using a GPS receiver and calculates its own position based on the received data. There are a number of GPS satellites orbiting the earth. A navigation system can receive GPS signals from three GPS satellites no matter where the vehicle is located on the earth and calculate its own position based on the GPS signals received from the three GPS satellites. The navigation system provides a variety of traffic information to vehicles such automobiles based on the information on its own position calculated as such. Although this navigation system has been usually employed in the position determination for and the navigation of large carriers such as aircrafts or ships, it has recently been widely used even in the automobiles and the like. The navigation system provides a user with a variety of information including the current position information of a vehicle, routing information from the current position to the destination of a vehicle, map information related to the position and routing information, traffic information and the like. Since using a map allows the user to easily understand the information on the current position and the like when the user receives the current position and other information from the navigation system, the map information is generally provided to the user together with the current position information and the like.
According to the prior art, such map information has been provided to a user via a storage medium such as CD ROM or DVD ROM. Such a conventional navigation system reads, if necessary, the map information stored in the storage medium such as CD ROM and then displays the read information on a predetermined display means. However, when the map information is updated in the conventional navigation system, the storage medium itself such as CD ROM should be replaced, and thus, this is very troublesome whenever the map information is updated later on. In other words, financial and time losses occur because the user should continue to purchase the CD ROM containing updated map information from a CD ROM provider. Further, since it is impossible for the map information provider to provide a user with a CD ROM in which the updated map information has been reflected in real time, the updated map information (for example, when roads, buildings and the like are newly created or destroyed) cannot be provided to the user in real time. In addition, according to another prior art referred to as so-called "telematics", navigation services using mobile devices such as mobile phones have been provided. The telematics services can guide a user to a destination using voice data. Further, when a traffic accident happens to the user's car, the telematics services automatically track the position of the accident car using GPS satellites and transmit the information on the position of the accident car to rescue services, hospitals or the like that are located nearest to the position of the accident, so that rescue activities can be promptly performed. In the conventional navigation services using mobile phones, however, there is a problem in that the map information cannot be stored in the mobile phone due to its limited memory capacity. Therefore, since the vehicle position information, traffic information and the like have been provided to the user in the form of voice or text without map information, it causes inconvenience to the user when utilizing this conventional navigation system.
Accordingly, there is a need for a navigation system that can reflect updated map information related to roads, etc. in real time by providing the map information to a mobile device via a communication network.
If map information is provided to the mobile device via a wireless communication network, it is an important issue to reduce the time taken in providing a map in order to provide the mobile device with map information in real time.
Meanwhile, in the navigation service, one of main services required by users is to provide path information obtained as a result of a path search.
The path search generally includes the steps of calculating a plurality of paths from a source to a destination based on map information stored in a predetermined numerical map database and then selecting an appropriate path (for example, the shortest path) from the calculated paths. At this time, since there are usually a plurality of paths from the source to the destination, some time is required to calculate the plurality of the paths until the appropriate path is selected. Such calculation of the path may cause a time delay or load in a predetermined system for searching a path until the result of the path search is provided to the mobile device.
As such, as the amount of works required in a path search increases, there is inconvenience in that the user of the mobile device should wait until information on the appropriate path is received. Further, a service company that provides navigation services should also have an apparatus of a sufficient capacity considering the load of a system for searching a path. Therefore, there is a need for a new method of shortening the time taken to search a path and reducing load of a system for searching a path.
Although it has been described above that path information and map information are received from a predetermined map providing server via a wireless communication network, the above method may be needed for the same reason even in a case where map information is provided from a predetermined map providing server via a wired communication network without providing map information through a wireless communication network as in the prior art, or a case where a path is searched in a user terminal by using map information stored in a recording medium.
Disclosure of Invention
The present invention is conceived to solve the aforementioned problems in the prior art. An object of the present invention is to provide a method and system for searching a path capable of reducing time taken to search a path based on predetermined road information and reducing load in a system for searching the path.
According to an aspect of the present invention for achieving the objects and solving the problems in the prior art, there is provided a method for searching a path, comprising the steps of maintaining road information corresponding to roads and layers which are associated with the road information and determined according to a predetermined criterion, in a predetermined numerical map database; searching a first path within a predetermined first distance from a source based on the road information associated with a predetermined first layer set including the one or more layers; searching a second path from the source from the predetermined first distance from a destination to a predetermined second distance based on the road information associated with a predetermined second layer set including the one or more layers; searching a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers; and generating a path from the source to the destination by using the first path, the second path, and the third path.
Preferably, a method for searching a path of the present invention further comprises the steps of receiving the source and the destination from a user's mobile device, and transmitting the generated path to the mobile device.
Preferably, a system for searching a path of the present invention performs the steps of receiving a current position of the mobile device from a GPS receiver of the mobile device; determining whether the mobile device deviates from the transmitted path based on the transmitted path and the current position; and if the user deviates from the transmitted path, setting the current position as the source.
In addition, a method for searching a path of the present invention may further comprise the steps of receiving a current position of the mobile device from a GPS receiver of the mobile device; determining whether the mobile device deviates from the transmitted path based on the transmitted path and the current position; and if the user deviates from the transmitted path, setting the current position as a source.
According to another aspect of the present invention, there is provided a method for searching a path which comprises the steps of maintaining road information in a predetermined numerical map database; calculating one or more first candidate paths from a source to a destination based on the road information; determining, as a second candidate path, a predetermined number of first candidate paths that reach a critical point located at a certain distance away from the destination, among the first candidate paths; stopping calculation of the first candidate paths that are not determined as the second candidate path; calculating the second candidate path from the critical point to the destination; and determining the second candidate path for which the calculation is completed as a path.
According to a further aspect of the present invention, there is provided a system for searching a path which comprises a numerical map database for maintaining road information corresponding to roads and layers which are associated with the road information and determined according to a predetermined criterion; a user receiving unit for receiving a source and destination from a mobile device of a user; a path search unit for searching a path from the source to the destination based on the road information; and a user transmission unit for transmitting the searched path to the mobile device, wherein the path search unit is configured to search a first path within a predetermined first distance from the source based on the road information associated with a predetermined first layer set including one or more layers, to search a second path from the source from the predetermined first distance from a destination to a predetermined second distance based on the road information associated with a predetermined second layer set including the one or more layers, to search a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers, and to generate a path from the source to the destination by using the first path, the second path, and the third path.
Brief Description of Drawings
FIG. 1 is a flowchart illustrating the steps for embodying a method for searching a path according to an embodiment of the present invention. FIG. 2 shows a network configuration of a system for searching a path that performs a method for searching a path according to an embodiment of the present invention.
FIG. 3 is a view illustrating an example of road information, in a method for searching a path according to an embodiment of the present invention. FIG. 4 is a view illustrating an example of road information maintained in a numerical map database and layers associated with the road information, in a method for searching a path according to an embodiment of the present invention. FIG. 5 is a view illustrating a case where a layer for a predetermined road is determined so as to secure the integrity of path search information, in a method for searching a path according to an embodiment of the present invention.
FIG. 6 (a) to (f) are views illustrating examples of input windows for inputting a source and destination, which are provided in a user's mobile device, and FIG. 6 (g) to (i) are views illustrating paths displayed in the mobile device, in the method for searching a path according to an embodiment of the present invention.
FIG. 7 is a view illustrating a method for searching a path according to an embodiment of the present invention. FIG. 8 is a view illustrating a path searched based on road information associated with first to third layer sets, in a method for searching a path according to an embodiment of the present invention.
FIG. 9 is a flowchart illustrating the steps for embodying a method for searching a path according to another embodiment of the present invention. FIG. 10 is a view illustrating a method for searching a path according to another embodiment of the present invention.
FIG. 11 is a block diagram showing the configuration of a system for searching a path according to another embodiment of the present invention.
FIG. 12 is an inner block diagram showing a typical computer system in accordance with an embodiment of the present invention.
Best Mode for Carrying Out the Invention
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a flowchart illustrating the steps for embodying a method for searching a path according to an embodiment of the present invention. The method for searching a path according to this embodiment can be performed in a predetermined system for searching a path. FIG. 2 shows the network configuration of a system for searching a path that performs the method for searching a path according to an embodiment of the present invention. Reference numeral 210 indicates a system for searching a path and reference numeral 230 indicates a mobile device connected to the system for searching a path 210 via a communication network 220. The system for searching a path 210 searches a path corresponding to a predetermined source and destination and then provides the searched path to the mobile device 230.
The system for searching a path 210 maintains road information and layers, which are associated with the road information and determined according to a predetermined criterion, in a predetermined numerical map database (SlOl).
The road information is data for specifying the road on a map and may be defined in various modes. FIG. 3 is a view for explaining exemplary road information. In FIG. 3, the road information includes a node, a link and an interpolation point. Dark points as indicated by Nl designate nodes, and lines for connecting the nodes as indicated by Ll3 L2 and L3 designate links. The node is information for indicating an intersecting point where roads cross or a dead place on a road, and the link provides information for indicating roads between the nodes.
Furthermore, interpolation points provide information for indicating points, on a curved road, through which the road passes. Generally, as the curvature of a road increases, a greater number of interpolation points are required in order to display the road.
As such, road information corresponding to a road can be defined. In addition, road information may be defined in a variety of manners.
FIG. 4 shows exemplary road information and layers associated with the road information, which are maintained in a numerical map database. According to another embodiment of the present invention, the layer associated with the road information is determined on the basis of one or more road types, the traffic of vehicles using the road and the number of lanes.
For example, regarding the type of road, a layer associated with an express highway or an urbanized express highway may be determined as layer 2, and a layer associated with common roads or provincial roads may be determined as layer 3.
Furthermore, even in case of the same provincial road depending on the number of lanes, a provincial road of 4 or more lanes may be defined as layer 3 and a provincial road of 4 or less lanes may be defined as layer 4. In addition, even in case of a provincial road of 4 or less lanes, a layer for a provincial road having a high coefficient of utilization, i.e. a provincial road having a lot of traffic, may be defined as layer 3. The average value of vehicles that employ the provincial road a day, the average value of vehicles that employ the provincial road in a specific time interval, or the like is calculated and is then reflected to determine layer. If the average value in a specific time interval is used, a search may be performed based on different layers depending on the time interval where users request paths, in a state where each layer in each time interval for single road information is maintained.
In other words, in principle, a layer associated with a road can be determined based on the type of road. The layer may be changed according to a variety of criteria. Further, the layer may be determined in order to secure the integrity of "path search information". FIG. 5 is a view for explaining a case where a layer for a predetermined road is determined so as to secure the integrity of path search information. As will be described later, the system for searching a path 210 searches a path based on road information associated with a predetermined layer set. Therefore, road information associated with layers included in the layer set is used as material for a path search, but road information associated with layers not included in the layer set is not used as material for the path search.
As shown in FIG. 5, a certain road may consist of four lanes except for some sections that are two lanes. At this time, respective links indicated by reference numerals L521 to L523 are classified by respective nodes, which are indicated by reference numerals N511 and N512. At this time, if a layer corresponding to road information is determined according to the type of road and the number of lanes, for example, for the links L521 and L522, layer 3 is maintained in the numerical map database, and for the link L523, layer 4 is maintained in the numerical map database.
As described later, however, if the system for searching a path 210 searches a path based on only road information associated with a layer set including only the layer 3 not the layer 4, the road (corresponding to the links L521 to L523 among road information) corresponds to a case where a road portion corresponding to the link L523 does not exist. Accordingly, there is a problem in that a path from the link L521 to a road corresponding to the link L522 is not searched. Therefore, in such a case, even when the type of road or the number of lanes differs, a layer associated with the link L523 needs to be set as layer 3 like the layer associated with the links L521 and L522. As such, by determining a layer associated with each type of road information on the basis of actual road conditions, it is possible to secure "the integrity of path search information". In other words, the same path search result as a case where a path is searched based on the whole road information can be obtained, while reducing the amount of calculation in a path search process by using layers.
Meanwhile, layer 2, layer 3 and the like are used to identify respective layers. Modes for storage and representing each layer may be quite different from the above case.
The system for searching a path 210 receives a source and destination from a user's mobile device 230 via the communication network 220 (S102). FIG. 6 (a) to (f) illustrate exemplary input windows for inputting source and destination information, which are provided in the mobile device 230.
In the input window of FIG. 6 (a), the user selects "Guide New Road", which is a menu provided for a path search. Like a "Name Search" (for example, "Seoul City Hall") method or an "Address Search" (for example, "142, Nonhyun-Dong') method in
FIG. 6 (b), the system for searching a path 210 provides one or more methods for allowing the user to input a source and destination. In FIG. 6 (c), if the user inputs
"Sasang-Gu Office" which is a keyword of a destination according to the name search method, a search result as in FIG. 6 (d) is displayed. The user can then select a desired destination from the search result.
Meanwhile, according to another embodiment of the present invention, the system for searching a path 210 further provides a function of setting a transit point.
The user can select a transit point, as shown in FIG. 6 (e). If the transit point is input, the system for searching a path 210 searches a path through the transit point among a path from the source to the destination and then provides the searched path to the user.
FIG. 6 (f) shows an input window for allowing the user to input a source. In this embodiment, although FIG. 6 (f) shows a case where the current position of the mobile device 230 (corresponding to a current position of the mobile device 230 received by a GPS receiver associated with the mobile device 230) is set as a source, the same method as the method for inputting the aforementioned destination can be used even in case of a source.
According to the above-mentioned method, the system for searching a path 210 searches a path from the source to the destination (S 103 to S 105), if the source and destination are input by the mobile device 230.
At this time, as shown in FIG. 7, it is assumed that an area within a predetermined first distance dl from the source is defined as a first area, an area within a predetermined second distance d2 from the destination is defined as a third area, and areas other than the first and third areas are defined as a second area.
The system for searching a path 210 searches a path from the source based on the road information associated with a predetermined first layer set including one or more layers, which are maintained in the numerical map database, in the first area (S103).
Similarly, the system for searching a path 210 searches a second path based on the road information associated with a second layer set including one or more layers in the second area (S 104). The system for searching a path 210 searches a third path up to the destination based on the road information associated with a predetermined third layer set including one or more layers in the third area (S 105).
In the method for searching a path according to this embodiment, a path is searched based on all or most road information in an area around a source and destination. A path is searched based on road information corresponding to an express highway, a national road and so on in the remaining areas. For example, if a user requests a path from "Seoul City Hall" to "Sasang-Gu
Office, Busan", it would be highly unnecessary to search a path for, for example, provincial roads, etc. around provincial cities other than a path corresponding to an express highway from Seoul Toll Gate to Busan Toll Gate, in areas except for the vicinity of Seoul City Hall and Sasang-Gu Office. In other words, according to the method for searching a path according to this embodiment, only a path for a road "having a high possibility that users may actually use" such as an express highway, a provincial road, etc. is searched in the second area. Consequently, it is possible to reduce the time taken for the system for searching a path 210 to search a path and reduce the amount of work necessary to search the path. Therefore, in the method for searching a path according to this embodiment, the first layer set and the third layer set are set to include a large number of layers. Thus, a path that is same as or similar to a path obtained based on all the road information containing residential streets in addition to main roads, etc. around the source and destination, is provided to a user. The second layer set is set to include a layer associated with road information corresponding to an express highway, main roads and the like. Consequently, it is possible to reduce the amount of calculation in the system for searching a path 210, while providing substantially the same path as a case where paths for the entire areas are searched based on the whole road information.
Furthermore, the values of the first and second distance dl and d2 may be the ■ same as or different from each other.
According to another embodiment of the present invention, the first and second distances dl and d2 are values input from the mobile device 230. For example, a user may input the dl as a small value regarding to the vicinity of a source that the user knows well its geographical features, whereas he/she may input the d2 as large value regarding a destination that the user knows little about its geographical features. By doing so, the user can receive a detailed path even for an area that is away from the destination.
Furthermore, the first and second distances may be distances that are set by an operator of the system for searching a path 210. Also, according to another embodiment of the present invention, the user may select one of what the system for searching a path 210 automatically sets the first and second distances and what the user directly inputs the first and second distances.
In addition, according to another embodiment of the present invention, the first layer set or the third layer set contains all the layers maintained in the numerical map database.
FIG. 8 is a view for explaining a path searched based on road information associated with the first to third layer sets. FIG. 8 (a) shows the vicinity of "Seoul City
Hall" being a source, and FIG. 8 (b) shows the vicinity of "Sasang-Gu Office" being a destination. FIG. 8 (a) and (b) show a case where the first and third layer sets include all the sets of layers. Therefore, the system for searching a path 210 searches a path by using the whole road information (each node, link and interpolation point) in first and third areas.
Furthermore, FIG. 8 (c) and (d) show the second areas between the source and the destination. As a second layer set for a second area has a small number of layers compared to the first and third layer sets, the system for searching a path 210 searches a path by using only road information on main roads, which appear to be highly used by users.
The system for searching a path 210 generates a path from the source ("Seoul City Hall") to the destination ("Sasang-Gu Office") by using the first to third paths obtained by performing the steps S 103 to S 105 (S 106).
The generated path is transmitted to the user's mobile device 230 (S 107). FIG. 6 (g) shows a map displayed in the mobile device 230 during the transmission time taken until when the system for searching a path 210 transmits the path to the mobile device 230. According to the method for searching a path depending on this embodiment, the transmission time is significantly reduced compared to the prior art. In particular, as in a case where a path from a Seoul area to a Busan area is searched, it will be evident that the width of the area reduced becomes increasingly large as an area to be searched becomes wider. After the path is transmitted, if the user clicks on "Start Road Guide" through the input window provided on the mobile device 230 as shown in FIG. 6 (h), the user can be provided with map data on which the path is reflected, as shown in FIG. 6 (i). Thick lines on the road in FIG. 6 (i) designate the paths.
Through the above-mentioned procedure, the user of the mobile device 230 may be provided with a requested path.
Meanwhile, as shown in FIG. 6 (h), a variety of services associated with a path search such as "Simulation Driving", "View Driving Path", "Destination Information" and "Reset Path" may be provided to a user. Such services may be performed by receiving predetermined data from the system for searching a path 210 or may be performed in the mobile device 230 such as "View Driving Path" and the like.
The system for searching a path 210 according to another embodiment of the present invention performs steps (S 108 to Sl 10) in preparation for a case where the user deviates from the transmitted path without moving along the path.
The system for searching a path 210 receives the current position of the mobile device 230 from the mobile device 230 (S108). The current position may be obtained from a GPS receiver associated with the mobile device 230. The GPS receiver may be built in the mobile device 230 or may be separately installed so as to transmit predetermined information to the mobile device 230.
The system for searching a path 210 frequently receives the current position of the mobile device 230 from the GPS receiver and determines whether the mobile device 230 deviates from the path based on the current position (S 109). According to another embodiment of the present invention, the system for searching a path 210 determines "Deviation of Path" when the mobile device 230 deviates from the path by a predetermined distance in a straight distance. Furthermore, a variety of decision methods using the current position may be employed.
If the mobile device 230 deviates from the path, the system for searching a path 210 sets the received current position as a source (SI lO) and then transmits the set source to the mobile device 230 (Si l l). The system for searching a path 210 repeats steps (S 104 to S 107) to provide the user with a new path. Therefore, the user can be provided with a new path based on a new position even when the user deviates from a path. Thereafter, a method for searching a path according to another embodiment of the present invention will be described. FIG. 9 is a flowchart illustrating the steps for embodying a method for searching a path according to another embodiment of the present invention. As in the aforementioned embodiment, this method may be performed in a predetermined system for searching a path. The method for searching a path according to this embodiment will now be described with reference to FIG. 10.
The system for searching a path has road information maintained in a predetermined numerical map database (S901), and calculates one or more first candidate paths from a source to a destination based on the road information (S902). According to another embodiment of the present invention, the source and destination are data input by a user using a mobile device.
Although the number of paths from the source to the destination may be only one, the number of paths is usually plural, including a path corresponding to the shortest distance. For this reason, a number of first candidate paths are calculated in step S902.
The system for searching a path determines, as a second candidate path, a predetermined number of first candidate paths that reached a critical point located at a certain distance (d3 in FIG. 10) from the destination among the first candidate paths (S903). A critical point is a point located on a circle indicated by dotted lines in FIG. 10. According to another embodiment of the present invention, the system for searching a path can solve an error problem with an actual distance due to error, etc. on map information, by determining whether the user reaches a critical point within an error range. In other words, if the error range is set to 20 m when the certain distance is 2 km, the system for searching a path determines the critical point from a point, which is away from the destination by 1.98 km, to a point, which is away from the destination by 2.02 km.
The system for searching a path stops calculating the first candidate paths that are not determined as the first candidate path (S904) and calculates the second candidate path from the critical point to the destination (S905).
The first candidate path that is determined as the second candidate path in step (S903) may be 1 or more in number. In other words, the system for searching a path may stop calculation for the remaining first candidate paths if there is a first candidate path that reaches the critical point at the fastest time. If the certain number is set to 2, the system for searching a path may stop calculation for the first candidate paths except for a first candidate path that reaches the critical point at the fastest time and a first candidate path that reaches the critical point at the second fastest time.
Meanwhile, with respect to the first candidate path that is selected as the second candidate path, a path from a source to a destination is calculated without stopping calculating the path. If a path up to the destination is completely calculated for the second candidate path, the system for searching a path determines the second candidate path as "Path" (S906). The determined path may be then provided to the user.
As shown in FIG. 10, there is a high possibility that first candidate paths from a source to a destination may be plural in nature. Most of the paths are ones not selected according to a predetermined criterion and by the system for searching a path. The predetermined criterion may include various factors such as total length of the path, the number of lanes corresponding to the path and the like. For example, the system for searching a path may select a path that will be provided to a user in various manners such as selecting a path whose total length is simply the shortest, or a path whose total length is the shortest among paths having the number of 2 or more lanes corresponding to a path. As shown in FIG. 10, however, a second candidate path for which a path up to the vicinity of the destination is completely calculate is usually determined as a path.
To continue to calculate the remaining first candidate paths may cause the load of the system for searching a path to increase and the time until the completion of a path search to be delayed.
In other words, in a prior art, after all the candidate paths are completely calculated, a path is not selected from the candidate paths. In the present invention, however, calculation for candidate paths except for candidate paths having a high possibility that will be selected as a path is stopped before its calculation is completed. Accordingly, in a method for searching a path according to this embodiment, the time taken in searching a path is reduced and the load in a system for searching a path is reduced.
In addition, there is provided a computer-readable recording medium containing program for implementing a method for searching a path according to the embodiments of the present invention. The computer-readable recording medium may contain program instructions, data files, data structures, or a combination thereof. The program instructions may be ones that are specially designed or written for the present invention or may be ones that are well known to those skilled in the field of computer software. For example, the computer-readable recording medium includes a magnetic medium such as a hard disk, a floppy disk and a magnetic tape, an optical medium such as CD-ROM and DVD, a magneto-optical medium such as a floptical disk, and hardware devices such as read only memory (ROM), random access memory (RAM) and flash memory that are specially configured to store and execute the program instructions. The medium may be a transfer medium such as an optical or metal line and waveguide, including a carrier wave that transmits signals for specifying the program instructions, data structures and the like. Examples of the program instructions may include high-level language codes executable by a computer using an interpreter as well as machine language codes such as those written by a compiler.
A system for searching a path according to an embodiment of the present invention will now be described. FIG. 11 is a block diagram illustrating the configuration of a system for searching a path according to another embodiment of the present invention. A numerical map database 1101 stores therein road information and layers that are associated with the road information and determined according to a predetermined criterion.
A receiving unit 1102 receives a source and destination from a user's mobile device 1110 via a communication network 1120. A path search unit 1103 searches a path up to the destination based on the road information. A transmission unit 1104 transmits the searched path to the mobile device 1110 via the communication network
1120, whereby the searched path is provided to the user.
In the above, the path search unit 1103 searches a first path within a predetermined first distance from a source based on the road information associated with a predetermined first layer set including one or more layers, searches a second path from the predetermined first distance away from the source to a predetermined second distance away from the destination based on the road information associated with a predetermined second layer set including the one or more layers, searches a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers, and generates a path from the source to the destination by using the first path, the second path and the third path.
The first and third layer sets, the first and second distances, and a path search and generating process in the path search unit 1103 are same as those described with reference to the aforementioned embodiment. Therefore, detailed explanation on them will be omitted for simplicity.
FIG. 12 shows an inner block diagram of a typical computer system in accordance with an embodiment of the present invention. The computer system 1200 includes any number of processors 1201 (also referred to as central processing units, or CPUs) that are coupled to storage devices including primary storage 1202 (typically a random access memory, or "RAM"), primary storage 1203 (typically a read only memory, or "ROM"). As is well known in the art, primary storage 1203 acts to transfer data and instructions uni-directionally to the CPU and primary storage 1202 is used typically to transfer data and instructions in a bi-directional manner. Both of these primary storage devices may include any suitable type of the computer-readable media described above. A mass storage device 1204 is also coupled bi-directionally to CPU 1201 and provides additional data storage capacity and may include any of the computer-readable media described above. The mass storage device 1204 may be used to store programs, data and the like and is typically a secondary storage medium such as
- a hard disk that is slower than primary storage. A specific mass storage device such as a CD-ROM 1206 may also pass data uni-directionally to the CPU. Processor 1201 is also coupled to an interface 1205 that includes one or more input/output devices such as such as video monitors, track balls, mice, keyboards, microphones, touch-sensitive displays, transducer card readers, magnetic or paper tape readers, tablets, styluses, voice or handwriting recognizers, or other well-known input devices such as, of course, other computers. Finally, processor 1201 optionally may be coupled to a computer or telecommunications network using a network connection as shown generally at 1207. With such a network connection, it is contemplated that the CPU might receive information from the network, or might output information to the network in the course of performing the above-described method steps. The above-described devices and materials will be familiar to those of skill in the computer hardware and software arts.
The hardware elements described above may be configured (usually temporarily) to act as one or more software modules for performing the operations of this invention.
Industrial Applicability
According to a method and system for searching a path described above, a path that is the same as or similar to a case where a path is searched based on the entire road information is provided to a user. Furthermore, it is possible to reduce the time needed for a path search and load in a system for searching a path that performs the path search. As such, as the time needed for the path search is shortened, the time from when a user requests a path search to when the user receives the requested path is shortened.
Furthermore, according to the present method for searching, a path, if the user deviates from the path, a current position of the user is set as a source and a new path is provided to the user. In addition, according to the present method for searching a path, calculation for candidate paths except for candidate paths having a high possibility that will be selected as a path is stopped before its calculation is completed. It is therefore possible to reduce the time needed for a path search and load in a system for searching a path.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims

1. A method for searching a path, comprising the steps of: maintaining road information corresponding to roads and layers which are associated with the road information and determined according to a predetermined criterion, in a predetermined numerical map database; searching a first path within a predetermined first distance from a source based on the road information associated with a predetermined first layer set including the one or more layers; searching a second path from the source from the predetermined first distance from a destination to a predetermined second distance based on the road information associated with/a predetermined second layer set including the one or more layers; searching a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers; and generating a path from the source to the destination by using the first path, the second path, and the third path.
2. The method as claimed in claim 1, wherein the first or third layer set is a set including all the layers.
3. The method as claimed in claim 1, further comprising the steps of: receiving the source and the destination from a mobile device of a user; and transmitting the generated path to the mobile device.
4 The method as claimed in claim 3, wherein a system for searching a path performs the steps of: receiving a current position of the mobile device from the mobile device using a GPS receiver; determining whether the mobile device deviates from the transmitted path based on the transmitted path and the current position; and setting the current position as the source when it is determined that the user deviates from the transmitted path.
5 The method as claimed in claim 1, wherein the predetermined criterion is at least one of types of the roads, traffic of vehicles using the roads, and the number of lanes of the roads.
6 The method as claimed in claim 1, wherein the predetermined first and second distances are determined by one of a distance input by a user and a distance set by an operator.
7. A method for searching a path, comprising the steps of: maintaining road information corresponding to roads in a predetermined numerical map database; calculating one or more first candidate paths from a source to a destination based on the road information; determining a predetermined number of first candidate paths, which reach a critical point located at a certain distance away from the destination, among the first candidate paths as a second candidate path; stopping calculation of the first candidate paths that are not determined as the second candidate path; calculating the second candidate path from the critical point to the destination; and determining the second candidate path for which the calculation is completed, as a path.
8. A computer-readable recording medium in which a program for implementing a method according to any one of claims 1 to 7 is recorded.
9. A system for searching a path, comprising: a numerical map database for maintaining road information corresponding to roads and layers which are associated with the road information and determined according to a predetermined criterion; a user receiving unit for receiving a source and destination from a mobile device of a user; a path search unit for searching a path from the source to the destination based on the road information; and a user transmission unit for transmitting the searched path to the mobile device, wherein the path search unit is configured to search a first path within a predetermined first distance from the source based on the road information associated with a predetermined first layer set including one or more layers, to search a second path from the source from the predetermined first distance from a destination to a predetermined second distance based on the road information associated with a predetermined second layer set including the one or more layers, to search a third path within the second distance away from the destination based on the road information associated with a predetermined third layer set including the one or more layers, and to generate a path from the source to the destination by using the first path, the second path, and the third path.
PCT/KR2003/002221 2003-06-18 2003-10-22 Method and system for finding path for navigation service WO2004111972A1 (en)

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