Junction guide device for providing guidance concerning looped branch road

• US 6,597,986 B2
• Filed: 04/25/2001
• Issued: 07/22/2003
• Est. Priority Date: 04/27/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Mikame, Masami
• Primary Examiner(s): Chin, Gary
• Application Number:
  US09/841,003
• Publication Number:
  US 20010037176A1
• Time in Patent Office: 818 Days
• Field of Search: 701/207, 701/208, 701/209, 701/211, 340/988, 340/990, 340/995
• US Class Current: 701/211
• CPC Class Codes: G01C 21/3632 Guidance using simplified or iconic instructions, e.g. using arrows G01C21/365 takes precedence

Abstract

A vehicle navigation system stores road data and a plurality of schematic diagrams of junctions. Each schematic diagram represents a common pattern of a road forking to a loop road at a junction and includes a representation of the loop road and the forking pattern at the junction. When a motor vehicle approaches a junction, the system automatically determines by using road data whether a guide route forks to a loop road at the junction, and displays an appropriate schematic diagram selected from the stored schematic diagrams. The displayed diagram enables the driver to know the forking direction of the guide route at the next junction and whether the guide route forks to a loop road at the junction.

Claims

1. A junction guide device for a vehicle comprising:

storage means storing road data;

control means programmed to set a guide route from a point of departure to a destination by referring to the stored road data; and

display means for displaying a forking direction of the guide route at least at a next junction concerning which guidance should be provided when the vehicle approaches a junction on the guide route,

wherein the storage means further stores a plurality of pictorial diagrams which pictorially represent predetermined common patterns of a road forking to a plurality of loop roads at a junction for every similar road pattern, each diagram pictorially representing an entire shape of the loop road, and

wherein the control mean is further programmed to determine by using the stored road data whether the guide route fork to a loop road at a junction concerning which guidance should be provided, and cause the display means to select and display the pictorial diagram closest corresponding to the junction upon determination that the guide route forks to the loop road at the junction after specifying a road pattern of the loop road.

2. A junction guide device as set forth in claim 1,

wherein the control means is further programmed to determine, by referring to the stored road data, which direction the guide route forks at each junction, and select and store the pictorial diagram that represents he determined forking direction at each junction,

wherein the control means is further programmed to determine, by using the stored road data, whether the guide route forks to the loop road at a junction concerning which guidance should be provided, and identify a pictorial diagram which corresponds to the junction and includes a representation of the loop road by referring to not only the pictorial diagram which corresponds to the junction and represents the forking direction at the junction but also another pictorial diagram which corresponds to another junction included in the loop road and represents the forking direction at the junction included in the loop road upon determination that the guide route forks to the loop road at the junction, and

wherein the display mean displays the identified pictorial diagram.

3. A junction guide device as set forth in claim 1,

wherein the storage means stores, as the road data, nodes and links which constitute a road, and the nodes and link which constitute a connection road have attributes of the connection road, and

wherein the control means determines whether the guide route forks to a loop road at a junction by using the links obtained by sequentially searching links that have the attributes of the connection road from a link that includes a node corresponding to the junction and has the attributes of the connection road to an end of a chain of links when the node corresponding to the junction has the attributes of the connection road.

4. A junction guide device as set forth in claim 1, wherein the pictorial diagram of a common pattern of road forking to a loop road at a junction represents the forking direction of the guide route at the junction and the looping direction of the loop road.

5. A junction guide device as set forth in claim 4, wherein when the pictorial diagram of a common pattern of a road forking to a loop road at a junction corresponds to a junction at which the guide route forks to a loop road and there exists a junction beyond the loop road, the display means also represents the forking direction of the guide route at a junction beyond the loop road.

6. A junction guide device as set forth in claim 4, wherein when the control means determines that another junction is within a predetermined distance from the junction, the display means also represents the direction from which another road joins the guide route at the another junction.

7. A junction guide device as set forth in claim 1, wherein the control means selects, based on an estimated shape of the junction, the nearest one of the pictorial diagrams to be displayed by the display means.

8. A junction guide device as set forth in claim 3, wherein the control means determines the loop road by checking whether an angular difference between an initial direction at a start point of the link and a present direction is equal to or greater than a reference angle.

9. A junction guide device for a vehicle comprising:

storage means storing road data;

control means programmed to set a guide route from a point of departure to a destination by referring to the stored road data; and

display means for displaying a forking direction of the guide route at least at a next junction concerning which guidance should be provided when the vehicle approaches a junction on the guide route,

wherein the storage means further stores a plurality of pictorial diagrams which pictorially represent predetermined common patterns of a road forking to a plurality of loop roads at a junction for every similar road pattern, each diagram pictorially representing an entire shape of the loop road, and

wherein the control means is further programmed to determine by using the stored road data whether the guide route forks to a loop road at each junction concerning which guidance should be provided, and determine and store a pictorial diagram corresponding to the junction upon determination that the guide route forks to the loop road at the junction, and

wherein the control means is further programmed to select and cause the display means to display the stored pictorial diagram closest corresponding to a junction after specifying a road pattern of the loop road.

10. A junction guide device as set forth in claim 9,

wherein the storage means stores, as the road data, nodes and links which constitute a road, and the stored nodes and links which constitute a connection road have attributes of the connection road, and

wherein the control means determines whether the guide route forks to a loop road at a junction by using the links obtained by sequentially searching links that have the attributes of the connection road from a link that includes a node corresponding to the junction and has the attributes of the connection road to an end of a chain of links when the node corresponding to the junction has the attributes of the connection road.

11. A junction guide device as set forth in claim 9, wherein the pictorial diagram of a common pattern of road forking to a loop road at a junction represents the forking direction of the guide route at the junction and the looping direction of the loop road.

12. A junction guide device as set forth in claims 11, wherein when the pictorial diagram of a common pattern of a road forking to a loop road at a junction corresponds to a junction at which the guide route forks to a loop road and there exists a junction beyond the loop road, the display means also represents the forking direction of the guide route at the junction beyond the loop road.

13. A junction guide device as set forth in claim 11, wherein when the control means determines that another junction is within a predetermined distance from the junction, the display means also represents the direction from which another road joins the guide route at the another junction.

14. A junction guide device as set forth in claim 10, wherein the control means determines the loop road by checking whether an angular difference between an initial direction at a start point of the link and a present direction is equal to or greater than a reference angle.

15. A navigation method for a vehicle comprising the steps of:

setting a guide route to destination by using road data stored in a memory device, the guide route including junction of roads;

checking whether a junction in the set guide route is a looped type by using the stored road data;

selecting, based on an estimated loop shape of the checked junction, the nearest one of a plurality of fixed looped road patterns stored in the memory device in generalized common forms respectively, when the checked junction is the looped type; and

displaying on a display device the set guide route along with the selected near one of the fixed looped road patterns based on an actual loop shape of the checked junction.

16. A navigation method as set forth in claim 15, wherein the checking step determines if the junction is the looped type by checking if a difference between an initial direction at a start of the junction and a present direction is greater than a reference.

17. A junction guide device comprising:

a position detector for detecting the present position of a motor vehicle;

a storage memory for storing road data, the road data including a plurality of guide route fork patterns, a plurality of guide route loop patterns and a plurality of pictorial junction representations;

a displaying means for displaying one of the plurality of pictorial junction representations;

a controller for controlling the displaying means, wherein the controller is further for;

determining a first angular distance between an approach road to a junction and a first exit road from the junction an a second angular distance between the approach road and a second exit road from the junction and also for determining a classification of the approach road, the first exit road and the second exit road;

selecting one of the plurality of guide route fork patterns based upon the classification, first angular distance and second angular distance;

selecting one of the plurality of guide route loop patterns when another junction in close proximity to the junction is a loop exit and combining the one of the plurality of guide route fork patterns and the one of the plurality of guide route loop patterns to form a combined pattern; and

selecting the one of the plurality of pictorial junction representations for display based upon the combined pattern if the another junction in close proximity to the junction is the loop exit.

18. A junction guide device as set forth in claim 17, wherein the controller is further for determining if the another junction is a loop exit by determining if an angular difference between a starting point of an exit link and a current point of the exit link is greater than or equal to a predetermined reference angle.