Method for adaptively constructing and revising road maps
View Patent ↗A method for constructing and revising road maps in a vehicle map database using vehicle location signals to provide traffic flow information for recognized vehicle patterns from past vehicle travel. The method includes identifying vehicle travel segments as a series of exemplar points from the location signals. Exemplar points in each travel segment are eliminated to define the travel segment by a beginning exemplar point and an ending exemplar point. A potential ending exemplar point may be redefined if an average location of the exemplar points from a line connecting the beginning point and the potential ending point is outside of a threshold distance. The travel segments are stored in a database, where each stored travel segment includes a travel time. The method compares new vehicle travel segments to the stored vehicle travel segments to identify a match, and then revise the vehicle travel time for the stored travel segments.
1. A method for constructing and revising road maps in a database for a vehicle, said method comprising:
identifying vehicle travel segments of the vehicle as a series of exemplar points using signals from a system that provides vehicle position;
eliminating intermediate exemplar points in each travel segment to define the travel segment by a beginning exemplar point and an ending exemplar point of the travel segment;
storing the travel segments in the database;
identifying a travel time associated with each stored travel segment;
comparing new vehicle travel segments to the stored vehicle travel segments to identify matches between the new travel segments and the stored travel segments, and wherein comparing new vehicle travel segments to the stored vehicle travel segments includes projecting points on the new travel segment to the stored travel segment using a line perpendicular to the stored travel segment;
replacing a potential ending exemplar point of a travel segment with a new ending exemplar point if the potential ending point causes an average distance between the exemplar points identifying the travel segment and a straight line between the beginning exemplar point and the potential ending exemplar point to be greater than a threshold distance; and
revising the travel time of a stored travel segment if a new travel segment does match a stored travel segment.
2. The method according to claim 1 wherein comparing new vehicle travel segments to the stored vehicle travel segments includes comparing and matching new travel segments to stored travel segments where a new travel segment is shorter than a stored travel segment and has different end points, or the stored travel segment is shorter than a new travel segment and has different end points.
3. The method according to claim 1 wherein comparing new travel segments to the stored travel segments includes projecting points on the new travel segment to the stored travel segment that are within a predetermined distance of the stored travel segment.
4. The method according to claim 1 further comprising identifying locations in the stored vehicle travel segments that define travel speeds where the flow of traffic changes.
5. The method according to claim 4 wherein the location where the flow of traffic changes identify a traffic signal location.
6. The method according to claim 4 wherein identifying locations where the flow of traffic changes include using the exemplar points in the travel segment to identify how fast the vehicle is traveling.
7. The method according to claim 1 wherein the system that provides the vehicle location signals is a GPS system.
8. The method according to claim 1 wherein the beginning exemplar point is a location where the vehicle is turned on or determined from a vehicle stay at a fixed point for a predetermined period of time.
9. A method for construction and revising road maps in a database for a vehicle, said method comprising:
identifying vehicle travel segments of the vehicle as a series of exemplar points using signals from a system that provides vehicle position;
eliminating intermediate exemplar points in each travel segment to define the travel segment by a beginning exemplar point and an ending exemplar point of the travel segment;
replacing a potential ending exemplar point of a travel segment with a new ending exemplar point if the potential ending point causes an average distance between the exemplar points identifying the travel segment and a straight line between the beginning exemplar points and the potential ending exemplar point to be greater than a threshold distance;
storing the travel segments in the database;
comparing new vehicle travel segments to the stored vehicle travel segments to identify matches between the new travel segments and the stored travel segments; and
revising statistical data associated with the stored vehicle travel segment if a new travel segment is found to match a stored travel segment.
10. The method according to claim 9 wherein comparing new vehicle travel segments to the stored vehicle travel segments includes comparing travel segments that only partially overlap.
11. The method according to claim 9 wherein comparing new vehicle travel segments to the stored vehicle travel segments includes comparing and matching new travel segments to stored travel segments where a new travel segment is shorter than a stored travel segment and has different end points, or the stored travel segment is shorter than a new travel segment and has different end points.
12. The method according to claim 9 wherein comparing new vehicle travel segments to the stored vehicle travel segments includes projecting points on the new travel segment to the stored travel segment using a line perpendicular to the stored travel segment.
13. The method according to claim 12 wherein comparing new travel segments to the stored travel segments includes projecting points on the new travel segment to the stored travel segment that are within a predetermined distance of the stored travel segment.
14. The method according to claim 12 wherein comparing new vehicle travel segments to the stored vehicle travel segments includes projecting a point from the new vehicle travel segment to the stored travel segment that identifies a curve or bend in the travel segment.
15. The method according to claim 9 wherein the system that provides the vehicle location signals is a GPS system.
16. The method according to claim 9 wherein the beginning exemplar point is a location where the vehicle is turned on or determined from a vehicle stay at a fixed point for a predetermined period of time.
17. The method according to claim 1 wherein comparing new vehicle travel segments to the stored vehicle travel segments includes comparing travel segments that only partially overlap.