Method for Monitoring the Vehicle Handling of a Two Track Vehicle

• US 20090069982A1
• Filed: 07/11/2008
• Published: 03/12/2009
• Est. Priority Date: 09/11/2007
• Status: Active Grant

• Current Assignee: Bayerische Motoren Werke AG
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Serarslan, Benan, von Groll, Max, Gietl, Stefan
• Granted Patent: US 8,280,591 B2
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B60T 2230/02 Side slip angle, attitude angle, floating angle, drift angle
• CPC Class Codes: B60T 8/172 Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters B60T8/17551 takes precedence
• CPC Class Codes: B60T 8/17555 specially adapted for enhancing driver or passenger comfort, e.g. soft intervention or pre-actuation strategies

Abstract

A method monitors the vehicle handling of a vehicle with respect to vehicle stability by comparing a measured variable, which reflects the yaw rate or the lateral acceleration, with a comparison value, which is derived from the steering angle, specified by the driver. The gradients of the regression lines, which are normalized in relation to each other, of the measured variable, on the one hand, and the comparison value, which represents the steering angle, on the other hand, are compared continuously over a number of analysis time windows. Upon finding a significant deviation between these gradients, an unstable driving condition is concluded. The difference between the gradients of the regression lines, which may be determined by a first order least squares method and normalized to the same units by a suitably applied amplification factor, are determined and compared with a suitably determined limit value, above which an instability is inferred. Alternatively, the measured variable and the comparison value, which represents the steering angle, can be analyzed for a linear or nonlinear dependence within an analysis time window by a coherence analysis; and on detection of a noteworthy nonlinearity, an unstable driving condition can be concluded.

Claims

1. A method for monitoring vehicle handling of a vehicle with respect to vehicle stability using a measured variable reflecting a yaw rate or lateral acceleration of the vehicle and a comparison value derived from a steering angle specified by a driver of the vehicle, the method comprising the acts of:

normalizing gradients of regression lines of the measured variable and the comparison value in relation to one another;

comparing continuously over a number of analysis time windows normalized gradients of the regression lines; and

upon detecting a significant deviation between the gradients, concluding an unstable driving condition of the vehicle.

2. The method according to claim 1, wherein the regression lines are determined via a first order least squares method and are normalized into the same units via an applied amplification factor;

and

further wherein a difference between the gradients of the regression lines is determined and compared with a predefined limit value, above which the unstable driving condition is inferred.

3. The method according to claim 1, wherein a time delay between a jump in a steering angle as the comparison value and a subsequent system response is considered in an analysis of the gradient.

4. The method according to claim 2, wherein a time delay between a jump in a steering angle as the comparison value and a subsequent system response is considered in an analysis of the gradient.

5. The method according to claim 1, further comprising the acts of:

determining a difference between sideslip angles at a front wheel and a rear wheel of the vehicle;

inferring an unstable driving condition of the vehicle when the difference between the sideslip angles exceeds a predefined limit value, even if there is no conclusion of an unstable driving condition from the comparison of the gradients of the regression lines.

6. The method according to claim 2, further comprising the acts of:

determining a difference between sideslip angles at a front wheel and a rear wheel of the vehicle;

inferring an unstable driving condition of the vehicle when tlhe difference between the sideslip angles exceeds a predefined limit value, even if there is no conclusion of an unstable driving condition from the comparison of the gradients of the regression lines.

7. The method according to claim 3, further comprising the acts of:

determining a difference between sideslip angles at a front wheel and a rear wheel of the vehicle;

inferring an unstable driving condition of the vehicle when the difference between the sideslip angles exceeds a predefined limit value, even if there is no conclusion of an unstable driving condition ftom the comparison of the gradients of the regression lines.

8. The method according to claim 4, further comprising the acts of:

determining a difference between sideslip angles at a front wheel and a rear wheel of the vehicle;

inferring an unstable driving condition of the vehicle when the difference between the sideslip angles exceeds a predefined limit value, even if there is no conclusion of an unstable driving condition from the comparison of the gradients of the regression lines.

9. A method for monitoring vehicle handling of a vehicle with respect to vehicle stability by comparing a measured variable indicative of a yaw rate or a lateral acceleration of the vehicle with a comparison value derived from a steering angle specified by a driver of the vehicle, the method comprising the acts of:

analyzing the measured variable and the comparison value indicative of the steering angle for a lineal or non-linear dependence within an analysis time window via a coherence analysis; and

determining that an unstable driving condition exists upon detecting a defined degree of non-linearity.

10. The method according to claim 9, wherein an area below a coherence line in a frequency range between 0 Hertz and 5 Hertz is analyzed, which reflects the coherence in values ranging from 1 to 0 in the frequency interval.

11. The method according to claim 10, wherein a gradient of a regression line of the coherence line, which reflects the coherence in values ranging from 1 to 0 in the frequency interval, is analyzed with respect to its amount in a frequency range extending up to frequency values notably higher than those specified by the driver.