Vehicle stability control system

• US 20070050112A1
• Filed: 08/25/2005
• Published: 03/01/2007
• Est. Priority Date: 08/25/2005
• Status: Active Grant

• Current Assignee: Robert Bosch Corporation (Robert Bosch GmbH), Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Nardi, Flavio, Kroehnert, Michael, Samsons, Andris, Jauch, Siegfried, Scott, Vaughan
• Granted Patent: US 7,966,113 B2
• Time in Patent Office: Days
• US Class Current: 701/41
• CPC Class Codes: B60T 2201/14 Electronic locking-differential
• CPC Class Codes: B60T 2220/03 Driver counter-steering; Avoidance of conflicts with ESP control
• CPC Class Codes: B60T 8/17555 specially adapted for enhancing driver or passenger comfort, e.g. soft intervention or pre-actuation strategies

Abstract

A vehicle stability system for a vehicle. In an embodiment the vehicle stability system includes a yaw rate sensor, an acceleration sensor, a steering sensor, a torque request sensor, and a controller. The controller is configured to receive an output of the yaw rate sensor, the lateral acceleration sensor, the steering sensor, and the torque request sensor, generate a torque signal and a braking signal, and transmit the torque signal to a differential in addition to transmitting the braking signal to a braking system.

Claims

1. A vehicle stability system for a vehicle, the system comprising:

a yaw rate sensor configured to generate an output indicative of a yaw rate of the vehicle;

an acceleration sensor configured to generate an output indicative of a lateral acceleration of the vehicle;

a steering sensor configured to generate an output indicative of a steering angle;

a torque request sensor configured to generate an output indicative of a torque request by a driver of the vehicle; and

a controller configured to

receive the output of the yaw rate sensor, the lateral acceleration sensor, the steering sensor, and the torque request sensor,

determine the need to modulate a request for torque by the driver of the vehicle by calculating an oversteering indicator and an understeering indicator,

generate a torque signal, and

transmit the torque signal to a differential.

2. The vehicle stability system of claim 1, wherein the oversteering indicator is determined using a lateral acceleration of the vehicle, the output of the yaw rate sensor, and a longitudinal velocity of the vehicle.

3. The vehicle stability system of claim 1, wherein the understeering indicator is determined using the output of the yaw rate sensor, a reference yaw rate, a target yaw rate, and a surface limited yaw rate.

4. The vehicle stability system of claim 1, wherein the yaw rate sensor and the acceleration sensor are combined in a single module.

5. The vehicle stability system of claim 1, further comprising a vehicle bus operable to transfer outputs from the sensors to other components.

6. The vehicle stability system of claim 1, wherein the controller is configured to transmit a braking signal to a braking system in addition to transmission of the torque signal.

7. The vehicle stability system of claim 1, wherein the controller is configured to generate multiple torque signals for transmission to multiple differentials.

8. The vehicle stability system of claim 1, wherein the output of the acceleration sensor is adjusted to compensate for banked surface conditions.

9. A method of stabilizing a vehicle using a vehicle stability system, the method comprising:

generating a target indicator, the target indicator representing a stable vehicle condition;

evaluating a vehicle driver input, the evaluation based at least partially on an acceleration request and a steering angle of the vehicle;

determining the presence of an understeering condition, an oversteering condition, or both based at least partially on a lateral acceleration of the vehicle, a yaw rate of the vehicle, a longitudinal velocity of the vehicle, and the vehicle driver input;

establishing an instability indicator based on whether an understeering condition, an oversteering condition, or both exists;

determining a torque control based at least partially on the instability indicator, the target indicator, and the driver input evaluation; and

applying the torque control.

10. A method of claim 9, further comprising applying a brake control that includes evaluating a braking condition in addition to applying the torque control.

11. A method of claim 10, wherein applying a brake control in addition to applying the torque control occurs after determining whether an instability condition exists.

12. The method of claim 9, wherein determining the presence of the understeering condition comprises comparing the output of the yaw rate sensor, a reference yaw rate, a target yaw rate, and a surface limited yaw rate.

13. The method of claim 12, wherein determining the reference yaw rate comprises evaluating a desired yaw rate of the vehicle driver using the vehicle driver input.

14. The method of claim 9, wherein determining the presence of the oversteering condition comprises comparing the yaw rate of the vehicle to the lateral acceleration and the longitudinal velocity of the vehicle.

15. The method of claim 9, wherein establishing the instability indicator comprises comparing the presence of an understeering condition to the presence of an oversteering condition.

16. The method of claim 9, wherein applying the torque control comprises variably applying a torque to each driven wheel of the vehicle.

17. The method of claim 9, wherein generating the target indicator comprises generating a target sideslip angle for the vehicle.

18. The method of claim 9, further comprising determining a braking condition based on at least one of a speed of the vehicle and the lateral acceleration of the vehicle.

19. The method of claim 9, wherein deciding to implement the torque control further comprises determining a set of entry conditions and a set of exit conditions.

20. The method of claim 19, wherein the entry and exit conditions are determined at least partially according to the instability indicator passing a threshold.

21. A vehicle having at least four wheels including a left front wheel, a right front wheel, a left rear wheel, and a right rear wheel, and also having a vehicle stability system that includes a braking function and a torque control function, the vehicle stability system comprising:

a steering angle sensor configured to sense a steering angle of the vehicle and generate a steering signal indicative of the same;

a yaw rate sensor configured to sense a yaw rate of the vehicle and generate a yaw rate signal indicative of the same;

an acceleration sensor configured to sense a lateral acceleration of the vehicle and generate an output indicative of the same;

at least one wheel speed sensor configured to sense at least one wheel speed and generate a wheel speed signal indicative of the same; and

a controller configured to receive the signal from the steering angle sensor, the signal from the yaw rate sensor, the output of the acceleration sensor, and the signal from the at least one wheel speed sensor and determine a stability correction, wherein the stability correction comprises information to variably apply a torque to at least one of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel using the torque control function in addition to applying a brake to at least one of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel using the braking function.

22. The vehicle stability system of claim 21, wherein the torque control function determines the existence of an oversteering condition, an understeering condition, or both.

23. The vehicle stability system of claim 22, wherein the oversteering condition is determined using a lateral acceleration of the vehicle, the yaw rate of the vehicle, and a longitudinal velocity of the vehicle.

24. The vehicle stability system of claim 22, wherein the understeering condition is determined using the yaw rate of the vehicle, a reference yaw rate, a target yaw rate, and a maximum yaw rate.

25. The vehicle stability system of claim 21, wherein the acceleration sensor and the yaw rate sensor are combined into a single sensor module.

26. The vehicle stability system of claim 21, wherein the signals generated by the steering angle sensor, the yaw rate sensor, the acceleration sensor, and the at least one wheel speed sensor are transmitted to the controller on a vehicle bus.

27. The vehicle stability system of claim 21, wherein the vehicle includes a differential operative to receive at least some information from the vehicle stability correction.

28. The vehicle stability system of claim 27, wherein a electromechanical or electro-hydraulic controllable coupling device is used to apply the torque to at least one of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel.

29. The vehicle stability system of claim 28, wherein the controllable coupling device is a clutch-type differential.

30. The vehicle stability system of claim 21, wherein the vehicle include a braking system operable to receive at least some information from the vehicle stability correction.

31. A vehicle stability system for a vehicle, the system comprising:

a steering angle sensor configured to sense a steering angle of the vehicle and generate a steering signal indicative of the same;

a yaw rate sensor configured to sense a yaw rate of the vehicle and generate a yaw rate signal indicative of the same;

an acceleration sensor configured to sense a lateral acceleration of the vehicle and generate an output indicative of the same;

at least one wheel speed sensor configured to sense a speed of at least one wheel of the vehicle and generate a wheel speed signal indicative of the same; and

a controller configured to receive the signal from the steering angle sensor, the signal from the yaw rate sensor, the output of the acceleration sensor, and the signal from the at least one wheel speed sensor and determine a stability correction, wherein the stability correction comprises information to variably apply a torque to at least one wheel of the vehicle using the torque control function in addition to applying a brake to at least one wheel of a vehicle using the braking function.