Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Vehicle subsystem or accessory control
Reexamination Certificate
1999-10-13
2001-10-30
Zanelli, Michael J. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Vehicle subsystem or accessory control
C701S048000, C180S282000
Reexamination Certificate
active
06311111
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and a device for detecting the tendency of a vehicle to roll over.
BACKGROUND INFORMATION
Methods and devices for detecting the tendency of a vehicle to roll over are known in various modifications from the related art.
German Patent No. 44 16 991 describes a method and a device for warning the driver of a truck of the risk of roll over when turning a corner. To do so, the type of vehicle and the relevant status data for the risk of roll over are determined before the vehicle enters the turn, and the risk of roll over or the critical speed limit for the latter is determined as a function of the radius of the curve and the center of gravity of the vehicle. A signal prompting the driver to reduce his speed is triggered when the prevailing road speed of the vehicle is the reason for the risk of roll over or a predetermined safety margin from the risk of roll over is no longer met. The vehicle's road speed at which there is with certainty no risk of roll over is determined on the basis of a roll-over equation. The roll-over equation includes the vehicle speed, the curve radius traveled by the vehicle, the height of the vehicle's center of gravity above the road surface and the wheel load imbalance. The wheel loads are determined with the help of wheel load sensors embedded in the road surface. If the road speed of the vehicle no longer meets a predetermined safety margin from the road speed at the limit of the risk of roll over, a signal is generated, warning the driver of the vehicle of excessive speed in turning the curve. The signal indicating excessive speed is triggered until the measured road speed has been reduced to an extent that rules out any risk of roll over. Furthermore, German Patent No. 44 16 991 shows that the wheel slip of the vehicle's wheels on the road surface can be determined and taken into account in evaluating the risk of roll over.
An object of the present invention is to improve upon the method and the device detecting the tendency of a vehicle to roll over.
SUMMARY OF THE INVENTION
A tendency of a vehicle to roll over about a vehicle axis oriented in the longitudinal direction of the vehicle is detected using a method according to the present invention. For this, a variable describing the wheel rpm is determined for at least one wheel. Furthermore, at least one variable representing the transverse dynamics of the vehicle is determined. A variable describing wheel behavior quantitatively is determined for at least one wheel at least as a function of the variable describing the wheel rpm of the corresponding wheel and one of the variables representing the transverse dynamics of the vehicle. Whether the vehicle has a tendency to roll over about a vehicle axis oriented in the longitudinal direction of the vehicle is determined at least as a function of the variable determined for the minimum of one wheel, describing the wheel behavior of this wheel quantitatively.
It should be pointed out here that when the “tendency of a vehicle to roll over” is used below, this refers to the “tendency of a vehicle to roll over about a vehicle axis oriented in the longitudinal direction of the vehicle.” The formulation “a vehicle axis oriented in the longitudinal direction of the vehicle” is to be understood as follows: first, the vehicle axis about which the vehicle has a tendency to roll over may be the actual longitudinal axis of the vehicle. Second, it may be a vehicle axis which is twisted by a certain angle with respect to the actual longitudinal axis of the vehicle. It does not matter here whether or not the twisted vehicle axis passes through the center of gravity of the vehicle. The case of the twisted vehicle axis should also permit an orientation of the vehicle axis such that the vehicle axis corresponds either to a diagonal axis of the vehicle or to an axis parallel to it.
Determination of a variable describing the wheel behavior quantitatively and as a function of which it is determined whether the vehicle has a tendency to roll over is the reason for the following advantage in comparison with the related art: since a tendency of a vehicle to roll over about a vehicle axis oriented in the longitudinal direction of the vehicle is reflected directly in the wheel behavior of the wheels of the vehicle, it is possible to determine quickly and accurately whether the vehicle has a tendency to roll over by using the method according to the present invention on the basis of analysis of a variable describing the wheel behavior quantitatively. It can be done quickly because a variable describing the wheel behavior quantitatively enters directly into the determination of the roll-over tendency. It is accurate because multiple wheels can be analyzed to determine the roll-over tendency, and because the variables which describe the wheel behavior are available as quantitative values and thus, for example, precisely gradated plausibility queries are possible.
The method according to the present invention of detecting a tendency of the vehicle to roll over can be advantageous in the context of, for example, a method of stabilizing the vehicle. Such a method may be advantageous for a method of preventing the vehicle from rolling over, for example.
If the vehicle has a tendency to roll over, at least braking measures are advantageously implemented on at least one wheel and/or engine measures and/or measures involving the chassis actuators are taken to stabilize the vehicle, in particular, to prevent the vehicle from rolling over.
It has proven to be advantageous that the absolute value of one of the variables representing the transverse dynamics of the vehicle, in particular, the absolute value of the variable describing the transverse acceleration and/or the absolute value of a variable describing the yaw of the vehicle is compared with a threshold value. Then a determination of whether the vehicle has a tendency to roll over is performed when the absolute value of the one variable representing the transverse dynamics of the vehicle is greater than the threshold value. Therefore, the method according to the present invention is activated only in those transverse dynamic vehicle situations in which the vehicle can be expected to have a tendency to roll over.
It is also advantageous if the drive slip and/or wheel slip prevailing on a wheel is determined for at least that one wheel, and its absolute value is compared with a corresponding threshold value, and if the determination of whether the vehicle has a tendency to roll over is performed as a function of this comparison. Different determinations of the tendency of the vehicle to roll over are performed on the basis of this comparison. Thus, if for at least one wheel the absolute value of the drive slip and/or wheel slip prevailing on this wheel is smaller than the corresponding threshold value, the determination of whether the vehicle has a tendency to roll over is performed at least as a function of the variable describing the wheel behavior quantitatively and determined for the minimum of one wheel in the instantaneous time increment. However, if the absolute value of the drive slip and/or wheel slip determined for at least one wheel is greater than the corresponding threshold value, the determination of whether the vehicle has a tendency to roll over is performed at least as a function of the variable describing the wheel behavior quantitatively and determined for at least one wheel in a preceding time increment.
Advantageously, a variable depending on the wheel load acting on the respective wheel is determined as the variable describing the wheel behavior of the respective wheel quantitatively. Variables describing the diameter or radius of the respective wheel are particularly advantageous because a displacement in the center of gravity of the vehicle due to turning a corner has a significant effect on the diameter of the vehicle's wheels, for example, and thus a tendency of a vehicle to roll over can be detected directly on the basis of
Leimbach Klaus-Dieter
Wetzel Gabriel
Kenyon & Kenyon
Robert & Bosch GmbH
Zanelli Michael J.
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