POSITION ESTIMATION FOR GROUND VEHICLE NAVIGATION BASED ON LANDMARK IDENTIFICATION/YAW RATE AND PERCEPTION OF LANDMARKS

• US 20110054791A1
• Filed: 08/25/2009
• Published: 03/03/2011
• Est. Priority Date: 08/25/2009
• Status: Active Grant

• Current Assignee: Southwest Research Institute
• Original Assignee: Southwest Research Institute
• Inventors: Surampudi, Bapiraju, Steiber, Joe
• Granted Patent: US 8,301,374 B2
• Time in Patent Office: Days
• US Class Current: 701/216
• CPC Class Codes: G01C 21/005 with correlation of navigation data from several sources, e.g. map or contour matching G01C21/30 takes precedence
• CPC Class Codes: G01C 21/12 executed aboard the object being navigated; Dead reckoning
• CPC Class Codes: G01C 21/30 Map- or contour-matching

Abstract

A landmark-based method of estimating the position of an AGV (autonomous ground vehicle) or conventional vehicle, which has an onboard database of landmarks and their location coordinates. During travel, the AGV looks for and identifies landmarks. It navigates according to position estimations that are based on measured yaw rate and speed. When a landmark is encountered and recognized, its true location coordinates are looked up from the database. These true coordinates are then used to enhance position estimation accuracy between landmarks.

Claims

1. A method of estimating the position of a ground vehicle during travel along a route, comprising:

storing in a database, a set of landmarks and landmark location coordinates for each landmark;

initializing position with known location coordinates;

receiving current yaw rate (W) and vehicle speed data (v);

using visual perception equipment to identify landmarks;

when no landmark is identified, using the following calculations or other forms of state estimation to estimate the vehicle'"'"'s current position data;

y_est=∫

v cos(H_est)dt

x_est=∫

v sin(H_est)dt

H_est=∫

{dot over (ψ

)}dt

when a landmark is identified, using the following calculations or other forms of state adjustment to determine vehicle location data;

y_est=y_landmark+y_offset

x_est=x_landmark+x_offset

H_est=θ

_landmark+θ

_offset

using the landmark location coordinates to correct the current position data.

2. The method of claim 1, wherein the visual perception equipment is LIDAR, Optical Camera, or Sonar.

3. The method of claim 1, wherein the landmark location coordinates are GPS coordinates.

4. The method of claim 1, wherein the vehicle normally uses live GPS-based navigation, but is programmed to use the method when no GPS signal is available.

5. The method of claim 1, wherein the vehicle is always navigated without a live GPS signal.

6. The method of claim 1, wherein the method is performed by equipment onboard the vehicle.

7. The method of claim 1, wherein at least one landmark is an intersection.

8. The method of claim 1, wherein at least one landmark is a lane marking.

9. The method of claim 1, wherein at least one landmark is a lane width.

10. A control unit for estimating the position of an autonomous ground vehicle during travel along a route, the vehicle having visual perception equipment, a yaw rate sensor, and vehicle speed sensor, comprising:

a landmark database for storing a set of landmarks and each landmark'"'"'s location coordinates;

a processing unit programmed to perform the following tasks;

to initialize position with known location coordinates;

to receive current yaw rate (T) and vehicle speed data (v);

to use the visual perception equipment to look for landmarks;

when no landmark is identified, to use the following calculations or other state estimators to estimate the vehicle'"'"'s current position data;

y_est=∫

v cos(H_est)dt

x_est=∫

v sin(H_est)dt

H_est=∫

{dot over (ψ

)}dt

when a landmark is identified, to use the following calculations or other forms of state adjustment to determine vehicle location data;

y_est=y_landmark+y_offset

x_est=x_landmark+x_offset

H_est=θ

_landmark+θ

_offset

to use the landmark location coordinates to correct the current position data.

11. The control unit of claim 10, wherein the visual perception equipment is LIDAR or optical camera or sonar.

12. The control unit of claim 10, wherein the location coordinates are GPS coordinates.

13. The control unit of claim 10, wherein the landmark database and processing unit are onboard the vehicle.

14. The control unit of claim 10, wherein the processing unit is in data communications with a remote server programmed to store landmark data and to extract features of upcoming portions of the route.

15. The control unit of claim 10, wherein at least one landmark is an intersection.

16. The control unit of claim 10, wherein at least one landmark is a lane marking.

17. The control unit of claim 10, wherein at least one landmark is a lane width.