Method for estimating the overturn risk of a vehicle

• US 20040119335A1
• Filed: 11/13/2003
• Published: 06/24/2004
• Est. Priority Date: 09/18/2000
• Status: Active Grant

• Current Assignee: Knorr-Bremse Systeme Fur Nutzfahrzeuge GMBH (Estate of Heinz Hermann Thiele)
• Original Assignee: Knorr-Bremse Systeme Fur Nutzfahrzeuge GMBH (Estate of Heinz Hermann Thiele)
• Inventors: Hany, Tamas, Merza, Valer, Szabo, Gergely
• Granted Patent: US 7,040,722 B2
• Time in Patent Office: Days
• US Class Current: 303/147
• CPC Class Codes: B60G 2800/0124 Roll-over conditions
• CPC Class Codes: B60G 2800/215 by applying a braking action on each wheel individually
• CPC Class Codes: B60G 2800/922 EBV - Electronic brake force distribution
• CPC Class Codes: B60T 2230/03 Overturn, rollover
• CPC Class Codes: B60T 8/17551 determining control parameters related to vehicle stability used in the regulation, e.g. by calculations involving measured or detected parameters
• CPC Class Codes: B60T 8/17554 specially adapted for enhancing stability around the vehicles longitudinal axle, i.e. roll-over prevention road vehicle drive control systems for roll-over prevention otherwise than by controlling a particular sub-unit B60W30/04

Abstract

The invention relates to a method for redundantly estimating, i.e. by means of various sub-methods, the risk of lateral overturn of a vehicle. One sub-method involves estimating the risk of overturn according to the actual braking state of the vehicle—braking or strong braking, or not braking or slight braking—by monitoring the rotational speed behavior of the wheels on the inside of the turn. Another sub-method involves pre-calculating the rolling motion of the vehicle about the longitudinal axis thereof over a short time span of, for example, 0.5 s to 1.5 s on the basis of instantaneous movement parameters and assessing the risk of overturn on the basis of the anticipated rolling motion.

Claims

1. Method of estimating an overturn risk of a vehicle, in which

the transverse acceleration of the vehicle is constantly determined, and

as a function of the lateral acceleration, the rotational wheel speed behavior of the vehicle wheels is monitored, characterized in that the overturn risk is determined redundantly, specifically

a) as a function of whether the vehicle is braked or unbraked by monitoring the rotational wheel speed behavior, and

b) by precalculating the rolling motion of the vehicle to be expected by using the transverse acceleration (a_trans).

2. Method according to claim 1, characterized in that the estimation of the overturn risk is carried out only when a defined transverse acceleration (a_{trans max}) is exceeded.

3. Method according to one of claims 1 or 2, characterized in that, in the case of an unbraked vehicle, a testing brake pressure is applied to a vehicle brake, which testing brake pressure is low with respect to the brake pressure of a full braking, and in that the existence of an overturn risk is assumed when the testing brake pressure results in a strong braking of the assigned wheel.

4. Method according to one of claims 1 to 3, characterized in that, in the case of a braked vehicle, the brake pressure of a vehicle brake is lowered, and in that the existence of an overturn risk is assumed when the rotational wheel speed of the assigned wheel increases only a little or not at all.

5. Method according to one of claims 1 to 4, characterized in that the time variation of the transverse acceleration (da_trans/dt) is used when precalculating the rolling motion.

6. Method according to one of claims 1 to 5, characterized in that the vibration period (T) or the frequency of the instantaneous rolling motion of the vehicle is used when precalculating the rolling motion.

7. Method according to one of claims 1 to 6, characterized in that, before the precalculation, disturbing influences are filtered out of the sensed movement parameters of the vehicle used for this purpose.

8. Method according to one of claims 1 to 7, characterized in that the expected rolling motion of the vehicle is precalculated for 0.5 to 1.5 s.

9. Method according to one of claims 1 to 8, characterized in that, when an overturn risk is determined, a braking intervention of the braking system of the vehicle takes place which reduces the overturn risk.

10. Method according to one of claims 1 to 9, characterized in that, when an overturn risk is recognized, on the basis of Steps a) and b) of claim 1, a braking intervention for the braking system is determined in each case, and that braking intervention is carried out which has the higher braking demand.

11. Method according to one of claims 1 to 10, characterized in that, in Step a), the rotational wheel speed behavior of wheels on the inside of the turn is monitored.

12. Method according to one of claims 1 to 11, characterized in that, in the case of an unbraked vehicle, the testing pressure is applied to vehicle brakes of wheels on the inside of the turn.

13. Method according to one of claims 1 to 12, characterized in that, in the case of a braked vehicle, the brake pressure is lowered at vehicle brakes of wheels on the inside of the turn.