Methods and systems for terrain-based localization of a vehicle

Patent metadata

Field	Value
Publication number	US-12474487-B2
Application number	US-202117477147-A
Country	US
Kind code	B2
Filing date	Sep 16, 2021
Priority date	Sep 17, 2020
Publication date	Nov 18, 2025
Grant date	Nov 18, 2025

Abstract

A method of terrain-based localization of a vehicle is provided. The method may include determining the vehicle is within a threshold distance of a road segment end point and comparing a measured road profile to a reference road profile associated with the road segment. A method of identifying a track (e.g., a lane) of a road segment road profile is provided. The method may include determining if a number of stored road profiles exceeds a threshold number of road profiles and identifying one or more clusters in the stored road profiles if the threshold number is exceeded.

First claim

The invention claimed is:

1 . A method for localizing a vehicle, the method comprising:
determining, using a terrain-based localization system, a first location of the vehicle at a first point in time; traveling a distance after the first point in time; and when the distance travelled by the vehicle after the first point in time exceeds a predetermined threshold distance from the first location: determining, using the terrain-based localization system, a second location of the vehicle at a second point in time; wherein the first location of the vehicle is determined by:
measuring vertical motion of one or more portions of the vehicle as the vehicle traverses a road;
based on the measured vertical motion, determining information about the road on which the vehicle is travelling;
comparing the determined information with reference road surface information; and
based at least partially on the comparison of the determined information and the reference road surface information, determining the first location of the vehicle, and
wherein determining the first location of the vehicle comprises determining a time point of correlation above a threshold between the determined information and the reference road surface information.

2 . The method of claim 1 , wherein the distance travelled by the vehicle since the first point in time is determined at least partially based on dead reckoning and/or global navigation satellite system (GNSS) measurements.

3 . The method of claim 1 , wherein the reference road surface information includes information about an aspect of the road as a function of position on the road.

4 . The method of claim 3 , wherein the reference road surface information includes information about variations in a surface of the road as a function of position on the road.

5 . The method of claim 1 , wherein the reference road surface information includes a road profile.

6 . The method of claim 1 , wherein the predetermined threshold distance is between 50 meters and 200 meters.

7 . A method for localizing a vehicle, the method comprising:
obtaining an approximate location of the vehicle with a first localization system; determining that the approximate location is within a threshold distance of an end point of a first road segment of a series of road segments extending along a length of a road, wherein the first road segment is associated with a first reference road profile; and measuring vertical motion of one or more portions of the vehicle as the vehicle traverses the first road segment; based on the measured vertical motion, determining information about the road segment on which the vehicle is travelling, the information including at least a measured road profile; and with a second localization system more precise than the first localization system, comparing the measured road profile with the first reference road profile when the approximate location of the vehicle is within the threshold distance of the end point and, based on the comparison of the measured road profile with the first reference road profile, determining a first time-point at which the vehicle is located at the end point of the first road segment, thereby localizing the vehicle to the end point of the first road segment at the first time-point; wherein determining the first time-point at which the vehicle is located at the end point of the first road segment comprises determining a time point of correlation above a threshold between the measured road profile and the first reference road profile.

8 . The method of claim 7 , wherein obtaining the approximate location of the vehicle with the first localization system is based at least in part on using a Global Navigation Satellite System (GNSS).

9 . The method of claim 7 , wherein obtaining the approximate location of the vehicle with the first localization system is based at least in part on using dead reckoning.

10 . The method of claim 7 , further comprising obtaining for each road segment:
an end point location of the respective road segment; and a reference road profile of the respective road segment.

11 . The method of claim 7 , further comprising using dead-reckoning to track further movement of the vehicle after the first time-point.

12 . The method of claim 7 , further comprising generating the measured road profile.

13 . The method of claim 12 , wherein generating the measured road profile comprises measuring vertical motion of one or more portions of the vehicle as the vehicle operates.

14 . The method of claim 13 , wherein generating the measured road profile further comprises filtering the measured vertical motion to remove effects of wheel-hop.

15 . The method of claim 13 , wherein generating the measured road profile further comprises differentiating the measured vertical motion with respect to time or distance.

16 . The method of claim 13 , wherein generating the measured road profile further comprises transforming the measured vertical motion from a time domain to a distance domain.

17 . The method of claim 7 , wherein the comparison of the measured road profile with the first reference road profile is carried out in response to the determination that the approximate location is within a threshold distance of the end point of the first road segment.

18 . The method of claim 7 , further comprising:
estimating a distance travelled by the vehicle since the first time-point; and upon determining that the distance travelled by the vehicle since the first time-point exceeds a predetermined distance:
comparing a second measured road profile with a second reference road profile, wherein the second reference road profile is associated with a second road segment that is geographically consecutive to the first road segment; and
based on the comparison between the second measured road profile and the second reference road profile, determining a second time-point at which the vehicle is located at the end point of the second road segment, thereby localizing the vehicle at the second time-point to the end point of the second road segment.

19 . The method of claim 7 , wherein each road segment has a predetermined length, and wherein comparing the measured road profile with the first reference road profile comprises comparing a last predetermined length of the measured road profile with the first reference road profile to identify a time of peak correlation, and wherein the first time-point is the time of peak correlation.

20 . The method of claim 1 , wherein determining the second location of the vehicle at the second point in time using the terrain-based localization system only occurs when the distance traveled by the vehicle after the first point in time exceeds the predetermined threshold distance.

21 . The method of claim 1 , wherein determining the first location of the vehicle comprises determining a time point of maximum correlation between the determined information and the reference road surface information.

22 . The method of claim 7 , wherein comparing the measured road profile with the first reference road profile only occurs when the approximate location of the vehicle is within the threshold distance of the end point.

23 . The method of claim 7 , wherein determining the first time-point at which the vehicle is located at the end point of the first road segment comprises determining a time point of maximum correlation between the measured road profile

Assignees

• Clearmotion Inc

Inventors

• Graves William
• Eisenmann John Parker

Classifications

• B60W60/001 Primary

  Planning or execution of driving tasks · CPC title

• B60W2552/53

  Road markings, e.g. lane marker or crosswalk · CPC title

• B60W2552/20

  Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments · CPC title

• B60W2554/4041

  Position · CPC title

• G01C21/3461

  Preferred or disfavoured areas, e.g. dangerous zones, toll or emission zones, intersections, manoeuvre types or segments such as motorways, toll roads or ferries · CPC title