Method and device for controlling the cornering speed of a vehicle

• US 20020161505A1
• Filed: 03/13/2002
• Published: 10/31/2002
• Est. Priority Date: 03/14/2001
• Status: Active Grant

• Current Assignee: Wabco GmbH (Wabco Holdings Incorporated)
• Original Assignee: Wabco GmbH (Wabco Holdings Incorporated)
• Inventors: Schmidt, Georg, Reich, Thomas
• Granted Patent: US 6,691,014 B2
• Time in Patent Office: Days
• US Class Current: 701/72
• CPC Class Codes: B60G 2400/104 lateral or transversal with regard to vehicle
• CPC Class Codes: B60G 2400/204 Vehicle speed
• CPC Class Codes: B60G 2600/02 Retarders, delaying means, dead zones, threshold values, cut-off frequency, timer interruption
• CPC Class Codes: B60G 2600/09 Feedback signal
• CPC Class Codes: B60G 2600/11 Feedforward signal
• CPC Class Codes: B60G 2600/14 Differentiating means, i.e. differential control
• CPC Class Codes: B60G 2600/17 Proportional control, i.e. gain control
• CPC Class Codes: B60G 2800/016 Yawing condition
• CPC Class Codes: B60G 2800/24 Steering, cornering
• CPC Class Codes: B60G 2800/70 Estimating or calculating vehicle parameters or state variables
• CPC Class Codes: B60K 31/0083 responsive to centrifugal force acting on vehicle due to the path it is following
• CPC Class Codes: B60T 2201/16 Curve braking control, e.g. turn control within ABS control algorithm
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60W 2050/0009 Proportional differential [PD] controller
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2520/125 Lateral acceleration
• CPC Class Codes: B60W 2520/14 Yaw
• CPC Class Codes: B60W 2520/20 Sideslip angle
• CPC Class Codes: B60W 2710/0672 Torque change rate
• CPC Class Codes: B60W 2720/14 Yaw
• CPC Class Codes: B60W 30/02 : Control of vehicle driving stability
• CPC Class Codes: B60W 30/14 : Adaptive cruise control

Abstract

The invention relates to a method and a device for controlling the cornering speed of a vehicle, with determination of the lateral acceleration and of the speed of the vehicle. In order to achieve a simple but effective capability of adjusting the vehicle speed to an optimum value, the yaw angular velocity is additionally determined, and a body slip angle is determined from the lateral acceleration, yaw angular velocity and vehicle speed. The body slip angle is compared with a threshold value. If the body slip angle exceeds this threshold, the set speed of the vehicle is reduced from the instantaneous actual speed, in a manner proportional to the body slip angle. If the body slip angle is below the threshold, the speed is released once again, or in other words the set speed is carried to the actual value of the speed; the driver can then accelerate once again. Adjustment of the set speed is achieved via adaptation of the engine torque. If the actual and set speeds differ, the engine torque is varied by a PD controller in such a way that the actual speed is adjusted to the set speed.

Claims

1. A method for controlling the cornering speed of a vehicle comprising the steps of determining a lateral acceleration and an actual speed of the vehicle, determining the yaw angular velocity of the vehicle, determining a body slip angle of the vehicle from the lateral acceleration, yaw angular velocity and actual speed of the vehicle, comparing the body slip angle with a predefined body slip-angle threshold value, and taking a corrective control action in response to a deviation of the body slip angle from the body slip-angle threshold value.

2. The method according to claim 1, further comprising the steps of deriving a set speed and by means of the corrective control action, reducing the set speed of the vehicle, starting from the actual speed of the vehicle, whenever the body slip-angle threshold value is exceeded by the body slip angle.

3. The method according to claim 2, wherein the set speed is reduced in proportion to the body slip angle.

4. The method according to claim 1, wherein the corrective control action is action on the engine.

5. The method according to claim 2, wherein the corrective control action is action on the engine.

6. The method according to claim 4, wherein control of the engine torque is provided as the action on the engine.

7. The method according to claim 5, wherein when the body slip angle is smaller than the body slip-angle threshold value, the set speed of the vehicle is carried to the actual speed of the vehicle once again, by the fact that the action on the engine has ended and the engine torque is released once again.

8. The method according to claim 7, wherein release of the engine torque takes place at a graduated rate.

9. A device for controlling the cornering speed of a vehicle having sensors for determining the speed and lateral acceleration of the vehicle comprising a sensor for the yaw angular velocity, a computing device for computing a body slip angle from the lateral acceleration, the yaw angular velocity and the actual speed of the vehicle, a threshold circuit for comparison of the body slip angle with a body slip-angle threshold value, a weighting circuit coupled to the output side of the threshold circuit, and which determines a correction value proportional to the determined body slip angle, a first summation point, in which a set speed of the vehicle is reduced from the actual speed of the vehicle by the correction value, a second summation point in which the actual speed of the vehicle is compared with the set speed of the vehicle in order to calculate a value of the control deviation, and a PD controller for adjusting the engine torque as a function of the value of the control deviation.

10. A method for controlling the cornering speed of a vehicle comprising the steps of determining a lateral acceleration and an actual speed of the vehicle, determining a yaw angular velocity of the vehicle, determining a body slip angle of the vehicle from the lateral acceleration, the yaw angular velocity and the actual speed of the vehicle, comparing the body slip angle with a body slip-angle threshold value, deriving a correction value based on a difference between the body slip angle and the predetermined threshold value, determining a vehicle set speed, deriving a control deviation based on a difference between the set speed and the actual speed and based on the control deviation, taking a corrective control action to control the speed of the vehicle.

11. The method according to claim 10, further comprising the step of weighting the body slip angle with a constant value to derive the correction value.

12. The method according to claim 10, further comprising the step of supplying the control deviation to a PD controller which acts on the engine torque to control the speed of the vehicle.

13. The method according to claim 10, wherein the vehicle set speed is reduced by the correction value when the body slip angle exceeds the body slip angle threshold.

14. The method according to claim 10, wherein when the body slip angle is smaller than the body slip-angle threshold value, the corrective control action is suspended and the set speed of the vehicle is carried to the actual speed of the vehicle once again.

16. The method according to claim 15, further comprising the steps of deriving a set speed and by means of the corrective control action, reducing the set speed of the vehicle, whenever the body slip-angle exceeds the body slip angle threshold value.

17. The method according to claim 15, wherein the corrective control action includes controlling the torque of the vehicle engine.

18. The method according to claim 17, wherein when the body slip angle and the body slip-angle threshold value are substantially identical, the engine torque is released.

19. The method according to claim 15, wherein the body slip angle is derived from a lateral acceleration, a yaw angular velocity and an actual speed of the vehicle.

15. A method for controlling the cornering speed of a vehicle comprising the steps of determining a body slip angle of the vehicle, comparing the body slip angle with a body slip-angle threshold value, and in response to a deviation of the body slip angle from the body slip-angle threshold value taking a corrective control action to the vehicle engine to control the speed of the vehicle.

20. In a vehicle having sensors for determining at least one of the vehicle'"'"'s speed, lateral acceleration and yaw angular velocity, an apparatus for controlling the cornering speed of the vehicle comprising a computing device for deriving a body slip angle, a threshold circuit for comparison of the body slip angle with a body slip-angle threshold value, a weighting circuit coupled to the output side of the threshold circuit, and which determines a correction value proportional to the body slip angle, a first summer, in which a set speed of the vehicle is reduced from the actual speed of the vehicle by the correction value, a second summer in which the actual speed of the vehicle is compared with the set speed of the vehicle in order to calculate a value of the control deviation, and means for performing a corrective action on the vehicle'"'"'s engine to control the vehicle'"'"'s speed.

21. The apparatus according to claim 20, wherein the means for performing a corrective action comprises a PD controller for adjusting the engine as a function of the value of the control deviation.