Method and system for controlling vehicle speed based on vehicle yaw rate and yaw acceleration

• US 6,317,679 B2
• Filed: 02/05/2001
• Issued: 11/13/2001
• Est. Priority Date: 12/22/1999
• Status: Expired due to Fees

• Current Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Original Assignee: Visteon Global Technologies Incorporated (Visteon Corporation)
• Inventors: Rahalm, Sam G., Sielagoski, Gerald L., Friedrich, Mark Peter
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): Hernandez, Olga
• Application Number:
  US09/778,123
• Publication Number:
  US 20010007966A1
• Time in Patent Office: 281 Days
• Field of Search: 701/96, 701/93, 701/72, 701/79, 701/91, 180/170, 303/140, 303/146, 340/967
• US Class Current: 701/96
• CPC Class Codes: B60K 31/0066 responsive to vehicle path curvature
• CPC Class Codes: B60K 31/0083 responsive to centrifugal force acting on vehicle due to the path it is following
• CPC Class Codes: B60T 2201/02 Active or adaptive cruise control system; Distance control
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 2210/24 Curve radius
• CPC Class Codes: B60T 8/1755 Brake regulation specially adapted to control the stability of the vehicle, e.g. taking into account yaw rate or transverse acceleration in a curve road vehicle drive control systems for control of driving stability otherwise than by controlling a particular sub-unit B60W30/02
• CPC Class Codes: B60T 8/246 Change of direction
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2552/20 Road profile, i.e. the change in elevation or curvature of a plurality of continuous road segments
• CPC Class Codes: B60W 2552/30 Road curve radius
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control

Abstract

In an adaptive vehicle speed control system, a method and system for controlling the speed of the vehicle while the vehicle is traversing a curved path. The method and system include sensing the yaw rate of the vehicle, determining the yaw acceleration based on the yaw rate, and determining a maximum allowed speed of the vehicle on the curved path based on the yaw rate and the yaw acceleration. The method and system also include limiting the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed.

Claims

1. In an adaptive speed control system for a vehicle, a method for controlling a speed of the vehicle while the vehicle is traversing a curved path, the method comprising:

sensing a yaw rate of the vehicle;

determining a yaw acceleration based on the yaw rate;

determining a maximum allowed speed of the vehicle on the curved path based on the yaw rate and the yaw acceleration; and

limiting the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed.

2. The method of claim 1 wherein the maximum allowed speed is capable of varying.

3. The method of claim 1 wherein determining a maximum allowed speed of the vehicle comprises:

determining a relative position of the vehicle on the curved path based on the yaw acceleration;

selecting a desired lateral acceleration of the vehicle based on the relative position of the vehicle on the curved path;

determining a radius of curvature of the curved path based on the yaw rate and a sensed vehicle speed; and

determining a maximum allowed speed of the vehicle based on the radius of curvature of the curved path and the selected vehicle lateral acceleration.

4. The method of claim 3 wherein determining a relative position of the vehicle on the curved path comprises:

determining that the vehicle is entering the curved path when the yaw acceleration is positive; and

determining that the vehicle is exiting the curved path when the yaw acceleration is negative.

5. The method of claim 4 wherein selecting a desired lateral acceleration of the vehicle comprises:

selecting a first lateral acceleration value when the vehicle is entering the curved path; and

selecting a second lateral acceleration value when the vehicle is exiting the curved path, wherein the first lateral acceleration value is less than the second lateral acceleration value.

6. The method of claim 3 wherein determining a radius of curvature of the curved path comprises calculating a radius of curvature according to the equation:

7. The method of claim 3 wherein determining a maximum allowed speed of the vehicle based on the radius of curvature of the curved path and the selected vehicle lateral acceleration comprises calculating a maximum allowed speed of the vehicle according to the equation:

8. The method of claim 1 wherein limiting the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed comprises generating a throttle control signal operative to control a throttle actuator to reduce the vehicle speed when the vehicle speed exceeds the maximum allowed vehicle speed.

9. The method of claim 1 wherein limiting the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed comprises generating a brake control signal operative to control a brake actuator to reduce the vehicle speed when the vehicle speed exceeds the maximum allowed vehicle speed.

10. The method of claim 1 wherein limiting the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed comprises limiting a commanded throttle position to a value no greater than a selected throttle position value.

11. In an adaptive speed control system for a vehicle, a system for controlling a speed of the vehicle while the vehicle is traversing a curved path, the system comprising:

a sensor capable of sensing a yaw rate of the vehicle; and

a controller capable of determining a yaw acceleration based on the yaw rate, determining a maximum allowed speed of the vehicle on the curved path based on the yaw rate and the yaw acceleration, and limiting the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed.

12. The system of claim 11 wherein the maximum allowed speed is capable of varying.

13. The system of claim 11 wherein, to determine a maximum allowed speed of the vehicle, the controller is further capable of determining a relative position of the vehicle on the curved path based on the yaw acceleration, selecting a desired lateral acceleration of the vehicle based on the relative position of the vehicle on the curved path, determining a radius of curvature of the curved path based on the yaw rate and a sensed vehicle speed, and determining a maximum allowed speed of the vehicle based on the radius of curvature of the curved path and the selected vehicle lateral acceleration.

14. The system of claim 13 wherein, to determine a relative position of the vehicle on the curved path, the controller is further capable of determining that the vehicle is entering the curved path when the yaw acceleration is positive, and determining that the vehicle is exiting the curved path when the yaw acceleration is negative.

15. The system of claim 14 wherein, to select a desired lateral acceleration of the vehicle, the controller is further capable of selecting a first lateral acceleration value when the vehicle is entering the curved path, and selecting a second lateral acceleration value when the vehicle is exiting the curved path, wherein the first lateral acceleration value is less than the second lateral acceleration value.

16. The system of claim 13 wherein, to determine a radius of curvature of the curved path, the controller is further capable of calculating a radius of curvature according to the equation:

17. The system of claim 13 wherein, to determine a maximum allowed speed of the vehicle based on the radius of curvature of the curved path and the selected vehicle lateral acceleration, the controller is further capable of calculating a maximum allowed speed of the vehicle according to the equation:

18. The system of claim 11 wherein, to limit the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed, the controller is further capable of generating a throttle control signal operative to control a throttle actuator to reduce the vehicle speed when the vehicle speed exceeds the maximum allowed vehicle speed.

19. The system of claim 11 wherein, to limit the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed, the controller is further capable of generating a brake control signal operative to control a brake actuator to reduce the vehicle speed when the vehicle speed exceeds the maximum allowed vehicle speed.

20. The system of claim 11 wherein, to limit the speed of the vehicle on the curved path to a value no greater than the maximum allowed vehicle speed, the controller is further capable of limiting a commanded throttle position to a value no greater than a selected throttle position value.