Method of assisting driver to negotiate a roadway

• US 20070050127A1
• Filed: 08/26/2005
• Published: 03/01/2007
• Est. Priority Date: 08/26/2005
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Sadekar, Varsha, Kellum, Carroll, Hermiz, Sarmad, Grimm, Donald
• Granted Patent: US 7,266,438 B2
• Time in Patent Office: Days
• US Class Current: 701/200
• CPC Class Codes: G01C 21/26 specially adapted for navigation in a road network
• CPC Class Codes: G01C 21/3697 Output of additional, non-guidance related information, e.g. low fuel level G01C21/3679 takes precedence

Abstract

A method of assisting a driver to negotiate a roadway by identifying a curve from a map database (12); calculating an estimated negotiable speed for the curve (14); advising the driver of the upcoming curve (16); warning the driver if he attempts to negotiate the curve at a speed that is greater than the estimated negotiable speed (18); and controlling the vehicle (10) in order to attempt to safely negotiate the curve (20). When the curve is identified in advance rather in real-time, identification of the curve, and possibly one or more characteristics of the curve as well as the estimated negotiable speed, may be stored for subsequent access and use (22). Furthermore, the advisory, warning, and control behaviors may be varied based on pre-established or determined conditions (24). Additionally, the actual vehicle state as it pertains to entering and exiting the curve may be determined (26).

Claims

1. A method of assisting a driver of a vehicle to negotiate a roadway, the method comprising the steps of:

(a) substantially automatically accessing an electronic map database, wherein the electronic map database represents a geometry of the roadway using a plurality of data points containing spatial information;

(b) estimating a heading and a curvature of a particular portion of the roadway on which the vehicle is traveling using the plurality of data points to identify a curve; and

(c) calculating an estimated negotiable speed for the identified curve based at least on one or more characteristics of the curve.

2. The method as set forth in claim 1, wherein in step (b) the heading is estimated by connecting straight line segments between at least three consecutive data points of the plurality of data points and averaging a heading into and out of a data point to represent the heading at that point.

3. The method as set forth in claim 1, wherein in step (b) the curvature is estimated by fitting a circle onto at least three consecutive data points of the plurality of data points, wherein the inverse of the radius of the circle represents an average curvature along the three consecutive data points.

4. The method as set forth in claim 1, wherein in step (b) the plurality of data points further contain information regarding a rate of directional change associated with the particular portion of the roadway, and wherein the curvature is estimated using the rate of directional change.

5. The method as set forth in claim 1, wherein step (b) further includes—

sequentially analyzing each point along the roadway, including comparing a curvature magnitude with a curve start threshold value;

identifying a curve start when a point has a curvature magnitude that is greater than the curve start threshold;

comparing subsequent points with an in-curve threshold value;

identifying a curve end when the curvature magnitude is less than the in-curve threshold;

identifying the curve start, curve end, and points therebetween as a candidate curve; and

collecting and processing information regarding the candidate curve to determine whether the candidate curve is a true curve.

6. The method as set forth in claim 1, wherein in step (c) the estimated negotiable speed is calculated as the square root of a radius of the curve multiplied by an acceptable lateral acceleration for the vehicle.

7. The method as set forth in claim 1, wherein in step (c) the estimated negotiable speed is adjusted based on a number of vehicular accidents associated with the curve.

8. The method as set forth in claim 1, wherein in step (c) the estimated negotiable speed is adjusted based on a current weather condition.

9. The method as set forth in claim 1, further including the step of advising the driver of the identified curve.

10. The method as set forth in claim 9, wherein the advisory is communicated to the driver a pre-established time before the vehicle reaches the curve.

11. The method as set forth in claim 9, wherein the advisory includes communicating to the driver one or more characteristics of the curve.

12. The method as set forth in claim 1, further including the step of warning the driver if the driver attempts to negotiate the curve at a speed that is greater than the estimated negotiable speed.

13. The method as set forth in claim 1, further including the step of controlling the vehicle as necessary to attempt to safely negotiate the curve.

14. The method as set forth in claim 13, wherein controlling the vehicle includes substantially automatically applying a brake in order to slow the vehicle to the estimated negotiable speed.

15. The method as set forth in claim 13, wherein controlling the vehicle includes substantially automatically at least partially disregarding an accelerator input by the driver in order to slow the vehicle to the estimated negotiable speed.

16. The method as set forth in claim 13, wherein controlling the vehicle includes substantially automatically at least partially reducing a fuel flow to an engine of the vehicle in order to slow the vehicle to the estimated negotiable speed

17. The method as set forth in claim 1, further including the step of varying an automatic response to the identified curve based on a condition.

18. The method as set forth in claim 17, wherein the condition is a pre-established driver preference.

19. The method as set forth in claim 17, wherein the condition is a time of day when the curve is encountered.

20. The method as set forth in claim 17, wherein the condition is whether the driver is familiar with the curve.

21. The method as set forth in claim 17, wherein the condition is a weather condition when the curve is encountered.

22. The method as set forth in claim 1, further including the step of storing information concerning the curve in a database for subsequent access and use.

23. The method as set forth in claim 22, wherein the curve and one or more characteristics of the curve are identified in advance and stored in a map database located on the vehicle.

24. The method as set forth in claim 22, wherein the curve and one or more characteristics of the curve are identified in advance and stored in a map database which is remote from the vehicle and which is accessed by the vehicle during operation of the vehicle.

25. The method as set forth in claim 1, further including the step of determining an actual state of the vehicle pertaining to entering and exiting the curve.

26. The method as set forth in claim 25, further including identifying in real-time an actual end of the curve.

27. The method as set forth in claim 26, wherein the actual end of the curve is identified based on a yaw rate of the vehicle.

28. The method as set forth in claim 26, wherein the actual end of the curve is identified based on a comparison between an absolute vehicle heading at the end of the curve and a curve heading at the end of the curve, wherein a convergence of the absolute vehicle heading and the curve heading indicates the actual end of the curve.

29. A method of assisting a driver of a vehicle to negotiate a roadway, the method comprising the steps of:

(a) substantially automatically accessing an electronic map database, wherein the electronic map database represents a geometry of the roadway using a plurality of data points containing spatial information;

(b) estimating a heading and a curvature of a particular portion of the roadway on which the vehicle is traveling using the plurality of data points to identify a curve;

(c) calculating an estimated negotiable speed for the identified curve based at least on one or more characteristics of the curve;

(d) advising the driver with respect to the upcoming curve;

(e) warning the driver if the driver attempts to negotiate the curve at a speed that is greater than the estimated negotiable speed; and

(f) controlling the vehicle as necessary to attempt to safely negotiate the curve.

30. A method of assisting a driver of a vehicle to negotiate a roadway, the method comprising the steps of:

(a) identifying a curve from an electronic map database;

(b) calculating an estimated negotiable speed for the identified curve based at least on one or more characteristics of the curve;

(c) advising the driver with respect to the upcoming curve;

(d) warning the driver if the driver attempts to negotiate the curve at a speed that is greater than the estimated negotiable speed;

(e) controlling the vehicle as necessary to attempt to safely negotiate the curve; and

(f) varying the advisory behavior of step (c), the warning behavior of step (d), and the control behavior of step (e) in response to one or more conditions.