Systems and methods for a navigational device with forced layer switching based on memory constraints

• US 6,581,003 B1
• Filed: 12/20/2001
• Issued: 06/17/2003
• Est. Priority Date: 12/20/2001
• Status: Active Grant

• Current Assignee: Garmin Limited
• Original Assignee: Garmin Limited
• Inventors: Childs, Michael, Beesley, Darin J.
• Primary Examiner(s): Beaulieu, Yonel
• Application Number:
  US10/027,159
• Time in Patent Office: 544 Days
• Field of Search: 701/202, 701/209, 701/25, 701/208
• US Class Current: 701/209
• CPC Class Codes: G01C 21/3446 Details of route searching algorithms, e.g. Dijkstra, A*, arc-flags, using precalculated routes

Abstract

Systems, devices and methods are provided for more efficient use of RAM and other resources in connection with a route calculation algorithm which quickly obtains a best or reasonable best path between two locations. The navigational aid device includes forced layer switching capabilities. The navigational aid device includes a processor and a memory adapted to communicate with the processor. The memory has cartographic data including any number of locations and data indicative of thoroughfares of a plurality of types connecting certain ones of the locations. The plurality of thoroughfares are organized in a hierarchy of detail levels. The processor operates on a route calculation algorithm to find a path between any two of the number of locations and the route calculation algorithm dynamically forces switching between different levels in the hierarchy of detail levels based on a set of criteria.

Claims

1. An electronic navigational aid device, comprising:

a processor;

a memory adapted to communicate with the processor, the memory having cartographic data including any number of locations, a set of criteria, and data indicative of thoroughfares of a plurality of types connecting certain ones of the locations;

wherein the plurality of thoroughfares are organized in a hierarchy of detail levels; and

wherein the processor operates on a route calculation algorithm to find a path between any two of the number of locations, and wherein the route calculation algorithm forces switching between different levels in the hierarchy of detail levels based on said set of criteria.

2. The device of claim 1, wherein the memory has a size of 512 Kilobytes or less.

3. The device of claim 1, wherein the hierarchy of detail levels includes a hierarchy of ever-decreasing detail levels such that a lowest level includes the greatest amount of detail.

4. The device of claim 1, wherein the set of criteria includes:

a number of jump segments requirement;

a distance requirement;

a minimum memory usage requirement;

a maximum memory usage requirement; and

an at least one jump segment requirement.

5. The device of claim 4, wherein the distance requirement includes a minimum distance requirement, the minimum distance requirement being at least 3 kilometers.

6. The device of claim 4, wherein the set of criteria are independently variable in order to tailor an aggressiveness with which the route calculation algorithm forces switching between different levels in the hierarchy of detail levels.

7. The device of claim 1, wherein device includes a portable electronic navigational aid device.

8. The device of claim 7, wherein the portable electronic navigational aid device includes a personal digital assistant (PDA).

9. The device of claim 7, wherein the portable electronic navigational aid device includes a wireless communications device.

10. An electronic navigational aid device with forced layer switching based on memory constraints, comprising:

a processor;

a memory in communication with the processor, the memory having cartographic data including any number of locations and data indicative of thoroughfares of a plurality of types connecting certain ones of the locations;

wherein the plurality of types of thoroughfares are contained in a data structure organized in a hierarchy of detail layers; and

wherein the processor operates on a route calculation algorithm and the hierarchy of detail layers to find a convergence between any two of the number of locations, and wherein the route calculation algorithm forces switching to another layer in the hierarchy of detail layers based on a set of criteria, the set of criteria including a maximum memory usage requirement and an at least one jump segment requirement.

11. The device of claim 10, wherein the hierarchy of detail layers includes a hierarchy of ever-decreasing details such that a lowest layer includes the greatest amount of detail.

12. The device of claim 11, wherein the maximum memory usage requirement for the lowest layer is no greater than 35% of available space on the memory.

13. The device of claim 10, wherein the set of criteria further includes:

a number of jump segments requirement;

a distance requirement; and

a minimum memory usage requirement.

14. The device of claim 13, wherein the minimum memory usage requirement at a greatest layer of detail in the hierarchy of detail layers is at least 2% of available space on the memory.

15. The device of claim 10, wherein the presence of a type of thoroughfare in any given layer of the hierarchy of detail layers is determined by a traversability of the thoroughfare.

16. The device of claim 10, wherein the device further includes a display in communication with the processor and the memory and adapted to display a solution between any two of the number of locations.

17. A navigation aid method for forced layer switching based on memory constraints, comprising:

organizing in memory data indicative of thoroughfares of a plurality of types according to a hierarchy of detail layers, the thoroughfares of the plurality of types connecting a number of locations;

using a route calculation algorithm to find a convergence between any two of the number of locations; and

wherein using the route calculation algorithm includes forcing layer switching to another layer in the hierarchy of detail layers by assigning a set of criteria to the algorithm, the set of criteria including a maximum memory usage requirement and an at least one jump segment requirement.

18. The method of claim 17, wherein organizing in memory data indicative of thoroughfares of a plurality of types according to a hierarchy of detail layers includes organizing the thoroughfares of a plurality of types by layers ever-decreasing detail such that a lowest layer includes the greatest amount of detail.

19. The method of claim 18, wherein assigning a maximum memory usage requirement includes assigning a maximum memory usage requirement for the lowest layer equal to or less than 35% of available space on the memory.

20. The method of claim 17, wherein assigning a set of criteria to the algorithm includes assigning a set of criteria which further includes:

a number of jump segments requirement;

a distance requirement; and

a minimum memory usage requirement.

21. The method of claim 17, wherein the set of criteria are independently variable at each layer in the hierarchy of detail layers.

22. The method of claim 20, wherein assigning the minimum memory usage requirement at a greatest layer of detail in the hierarchy of detail layers is at least 2% of available space on the memory.

23. The method of claim 20, wherein organizing in memory data indicative of thoroughfares of a plurality of types according to a hierarchy of detail layers includes organizing the thoroughfares of a plurality of types by a traversability of the thoroughfares.

24. The method of claim 17, wherein the method includes a computer-accessible medium having executable instructions stored thereon capable of directing a processor to perform the method.

25. A navigation aid method for forced layer switching, comprising:

using a data structure indicative of thoroughfares of a plurality of types organized according to a hierarchy of detail layers and having node locations connecting the thoroughfares of the plurality of types;

beginning at a first node location, evaluating a number of adjacent nodes for a convergence between a first node location and a second node location;

for each evaluated adjacent nodes, evaluating a next adjacent node;

maintaining a list of nodes having a jump segment to a next layer in the hierarchy of detail layers and maintaining a running total of nodes explored from a

given jump segment node;

maintaining a set of criteria; and

forcing a layer switch in the hierarchy of detail layers based on said set of criteria.

26. The method of claim 25, wherein forcing a layer switch in the hierarchy of detail layers based on a set of criteria includes forcing a layer switch when at least one jump segment has been found and a maximum memory allowance has been utilized for a given layer, the maximum memory allowance for each given layer being independently variable.

27. The method of claim 26, wherein the method further includes preventing a layer switch in the hierarchy of detail layers until a requisite number of jump segments have been found in combination with a requisite number in the running total of nodes explored from a given jump segment node, a minimum distance from the first node location has been explored, and a minimum memory space has been utilized for a given layer.

28. The method of claim 27, wherein, in the method, forcing a layer switch preempts preventing a layer switch.

29. The method of claim 27, wherein the requisite number of jump segments in combination with a requisite number in the running total of nodes explored from a given jump segment node, the minimum distance from the first node location that has been explored, and the minimum memory space utilization are all independently variable for each given layer.

30. The method of claim 29, wherein each given layer includes a number of alternatives for the requisite number of jump segments and requisite number in the running total of nodes explored from a given jump segment node combinations.

31. The method of claim 25, wherein the method further includes, simultaneous with evaluating a number of adjacent nodes beginning at a first node location, beginning at a second node location and evaluating a number of adjacent nodes thereto for a convergence between a first node location and the second node location.

32. The device of claim 31, wherein the method further includes selecting a solution from a number of convergences between the first node location and the second node location.

33. A navigation system for forced layer switching, comprising:

a server having a processor and memory, the memory having cartographic data including any number of locations and data indicative of thoroughfares of a plurality of types connecting certain ones of the locations, and wherein the plurality of types of thoroughfares are contained in a data structure organized in a hierarchy of detail layers;

wherein the processor operates on a route calculation algorithm and the hierarchy of detail layers to find a convergence between any two of the number of locations; and

wherein the route calculation algorithm dynamically forces switching to another layer in the hierarchy of detail layers based on a set of criteria, the set of criteria including a maximum memory usage requirement which is independently variable on a per layer basis.

34. The navigation system of claim 33, wherein the system further includes:

a mass data storage adapted to store navigation data; and

a navigation device adapted to communicate with and retrieve navigation data from the server via a communication channel, wherein the navigation device includes a display adapted to display a convergence between any two of the number of locations.

35. The navigation system of claim 34, wherein the communication channel includes a wireless channel.

36. The navigation system of claim 34, wherein the server includes a processor adapted to respond to a request from the navigation device by performing calculations on the cartographic data and transmitting results to the navigation device.

37. The navigation system of claim 34, wherein the navigation device adapted to communicate with and retrieve navigation data from the server using cellular communication technology.