Method of assisting driver to negotiate a roadway

• US 7,266,438 B2
• Filed: 08/26/2005
• Issued: 09/04/2007
• 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 (General Motors Company)
• Inventors: Grimm, Donald K., Hermiz, Sarmad Y., Kellum, Carroll C., Sadekar, Varsha
• Primary Examiner(s): Black; Thomas
• Assistant Examiner(s): Peche; Jorge O
• Application Number:
  US11/212,896
• Publication Number:
  US 20070050127A1
• Time in Patent Office: 739 Days
• Field of Search: 701/210, 701/26, 701/201, 701/209, 701/208, 701/211, 701/221, 701/224, 701/70, 701/72, 701/93, 701/1, 701/213, 340/438, 340/441, 340/460, 340/990, 340/995, 340/988
• US Class Current: 701/93
• 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 curved roadway, by identifying a true curve, determining an estimated negotiable speed for the true curve, and assisting the driver when an actual speed of the vehicle exceeds the estimated negotiable speed, 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 magnitude of a particular portion of the roadway on which the vehicle is traveling using the spatial information of the plurality of data points, and identifying the true curve based on the heading or curvature and by comparing the curvature magnitude against a curve start threshold;

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

(d) determining the actual speed of the vehicle, comparing the actual speed and estimated negotiable speed, and autonomously generating a response when the actual speed of the vehicle exceeds the estimated negotiable speed.

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 magnitude 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 magnitude 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 for each point 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 curvature magnitudes for subsequent points with an in-curve threshold value, after a curve start has been determined;

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

determining the true curve by collecting and processing information regarding the candidate curve and comparing the information to at least one threshold.

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, wherein step (d) further includes 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 1, step (d) 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.

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

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

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

15. The method as set forth in claim 14, wherein the condition is a pre-established driver preference.

16. The method as set forth in claim 14, wherein the condition is a time of day when the curve is encountered.

17. The method as set forth in claim 14, wherein the condition is whether the driver is familiar with the curve.

18. The method as set forth in claim 1, further including the step of determining the yaw rate of the vehicle when entering and exiting the curve.

19. The method as set forth in claim 18, further including identifying in real-time an actual end of the curve.

20. The method as set forth in claim 19, wherein the actual end of the curve is identified based on a yaw rate of the vehicle.

21. The method as set forth in claim 19, 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.

22. A method of assisting a driver of a vehicle to negotiate a curved roadway, by identifying candidate curves, calculating a true curve among the candidate curves, determining an estimated negotiable speed for the true curve, and warning the driver when the speed of the vehicle exceeds the estimated negotiable speed, 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 spatial information of the plurality of data points, and identifying a candidate curve based on the heading or curvature and based on a first threshold;

(c) calculating a true curve based on the candidate curve and a second threshold, and calculating an estimated negotiable speed for the identified true curve based at least on one or more characteristics of the curve;

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

(e) warning the driver if the driver attempts to negotiate the true 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 true curve.

23. A method of assisting a driver of a vehicle to negotiate a curved roadway, by determining an estimated negotiable speed, and warning the driver when the speed of the vehicle exceeds the estimated negotiable speed, the method comprising the steps of:

(a) identifying a curve from an electronic map database including a plurality of data points containing spatial information, by estimating a heading and a curvature magnitude for each of the data points and comparing the curvature magnitudes to curve start and in-curve thresholds;

(b) calculating the 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.