Model based method to assess road curvature effect on travel time and comfort for route planning

• US 8,306,732 B2
• Filed: 08/20/2009
• Issued: 11/06/2012
• Est. Priority Date: 08/18/2009
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Hoffmann, Gabriel M.
• Primary Examiner(s): Mawari, Redhwan k
• Application Number:
  US12/544,706
• Publication Number:
  US 20110046877A1
• Time in Patent Office: 1,174 Days
• Field of Search: 701/201, 701/408, 701/410, 701/424, 701/425, 701/468, 701/467, 340/995.19, 340/995.22, 340/995.23
• US Class Current: 701/408
• CPC Class Codes: G01C 21/3461 Preferred or disfavoured areas, e.g. dangerous zones, toll or emission zones, intersections, manoeuvre types, segments such as motorways, toll roads, ferries
• CPC Class Codes: G01C 21/3492 employing speed data or traffic data, e.g. real-time or historical traffic control systems for road vehicles involving transmission of navigation instructions to the vehicle G08G1/0968

Abstract

Methods and systems for assessing the effect of road curvature on the travel time and the comfort level of a path determined by a ground based route planning system. The methods and systems identify a path and determine an allowable speed profile of the path, wherein the allowable speed profile satisfies a cross track acceleration constraint. Thereafter, the methods and systems determine an optimal speed profile of the path, wherein the optimal speed profile satisfies both an along track acceleration constraint and a speed constraint. Using the optimal speed profile, the road curvature of a path may be factored into a determination of the traversal time of the path. Additionally, using the optimal speed profile, the road curvature of a path may be used to derive a comfort level of the path and/or to provide driver assistance.

Claims

1. A method for assessing road curvature of a path, including a plurality of waypoints, said method comprising the steps of:

a) receiving a pre-path, including a plurality of waypoints;

b) generating the path from the pre-path, the generating including generating a finer sampling of waypoints from the plurality of waypoints of the pre-path to create the plurality of waypoints of the path;

c) determining an allowable speed profile of the path, wherein said allowable speed profile includes an allowable speed for the each of the plurality of waypoints, wherein the allowable speed for the each of the plurality of waypoints satisfies a cross track acceleration constraint; and

,

d) determining an optimal speed profile of the path, wherein said optimal speed profile includes an optimal speed for the each of the plurality of waypoints, wherein the optimal speed for the each of the plurality of waypoints satisfies both an along track acceleration constraint and a speed constraint, wherein said speed constraint is a minimum of the desired speed and the allowable speed, wherein determining the optimal speed profile includes;

sweeping through the plurality of waypoints in a first direction to determine an along track acceleration profile, wherein the along track acceleration profile satisfies a negative acceleration constraint; and

,

sweeping through the plurality of waypoints in a second direction to update the along track acceleration profile, wherein the updated along track acceleration profile satisfies both a negative acceleration constraint and a positive acceleration constraint;

wherein the method is performed by use of at least one processor.

2. The method of claim 1, wherein the path is a space-indexed path.

3. The method of claim 1, wherein the desired speed of the each of the plurality of waypoints is a driving speed limit.

4. The method of claim 1, wherein the allowable speed profile is determined using an approximate path curvature of the path.

5. The method of claim 1, further comprising determining an optimal travel time of the path based upon the optimal speed profile.

6. The method of claim 1, further comprising determining a comfort level of the path based upon a frequency response of the path.

7. The method of claim 6, wherein the frequency response of the path is based upon the optimal speed profile.

8. The method of claim 1, wherein the optimal speed profile is determined simultaneously with the path.

9. A system for assessing road curvature of a path, wherein said path includes a plurality of waypoints, wherein each of said plurality of waypoints includes a desired speed, said system comprising:

at least one processor performing the method according to claim 1.

11. The method of claim 6, wherein the frequency response of the path is a frequency response of one of:

1) an along track acceleration profile of the optimal speed profile; and

     2) a cross track acceleration profile of the optimal speed profile.

10. A method for assessing road curvature of a path, including a plurality of waypoints, said method comprising the steps of:

a) determining an allowable speed profile of the path, wherein said allowable speed profile includes an allowable speed for the each of the plurality of waypoints, wherein the allowable speed for the each of the plurality of waypoints satisfies a cross track acceleration constraint;

b) determining an optimal speed profile of the path, wherein said optimal speed profile includes an optimal speed for the each of the plurality of waypoints, wherein the optimal speed for the each of the plurality of waypoints satisfies both an along track acceleration constraint and a speed constraint, wherein said speed constraint is a minimum of the desired speed and the allowable speed;

c) determining a frequency response of each of an along track acceleration profile of the optimal speed profile and a cross track acceleration profile of the optimal speed profile;

d) determining whether the acceleration profiles include frequencies between approximately 0.15 hertz and approximately 0.25 hertz to determine a comfort level of traversing the path according to the optimal speed profile; and

,

e) generating the path from a plurality of potential sub-paths, wherein each of the potential sub-paths is penalized based on a frequency response, the frequency response being a frequency response of one of;

     1) an along track acceleration profile of an optimal speed profile of the potential sub-path; and

     2) a cross track acceleration profile of an optimal speed profile of the potential sub-path;

wherein the method is performed by use of at least one processor.

12. The method of claim 10, further including:

notifying a user in response to the comfort level being less than a predetermined level.

13. The method of claim 10, further including:

receiving a request from a user for the comfort level; and

,

providing an indication of the comfort level to the user in response to receiving the request.

14. The method of claim 10, further including:

generating a new path including a comfort level less than a predetermined level in response to the comfort level of the path being less than the predetermined level.