Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – Indication or control of braking – acceleration – or deceleration
Reexamination Certificate
1999-10-18
2001-08-07
Cuchlinski, Jr., William A. (Department: 3661)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
Indication or control of braking, acceleration, or deceleration
C180S282000, C280S005507, C303S146000, C701S091000
Reexamination Certificate
active
06272420
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for detecting a tilt tendency of a vehicle.
BACKGROUND INFORMATION
Methods and apparatuses for detecting a tilt tendency of a vehicle are known from the existing art in many modifications.
German Patent No. 44 16 991 describes a method and a device for warning the driver of a commercial vehicle of a tilt hazard when driving around a curve. To accomplish this, before the vehicle is driven into a curve, the vehicle model and the status data relevant to the tilt hazard are sensed, and the tilt risk and the speed limit governing it are determined as a function of the vehicle center of gravity and the curve radius. A signal requesting a speed reduction is triggered if the current speed of the vehicle constitutes a tilt risk, or if a predefined safety margin in terms of tilt hazard has been breached. The vehicle speed at which a tilt hazard definitely does not exist is determined from a tilt equation. The tilt equation comprises, inter alia, the vehicle speed, curve radius through which the vehicle is traveling, height of the vehicle center of gravity above the road surface, and any imbalance in wheel loads. Wheel loads are ascertained with the aid of wheel load sensors embedded in the road surface. If the vehicle speed violates a predefined safety margin with respect to the vehicle speed lying at the tilt hazard limit, a signal is generated warning the driver of the vehicle of excessive speed while traveling through the curve. The signal indicating the excessive vehicle speed is triggered until the particular measured speed is reduced to a degree which excludes any risk of tilt. In addition, German Patent No. 44 16 991 indicates that slippage of the wheels of the respective vehicle on the road surface can be ascertained and can be taken into account in assessing the tilt hazard.
It is an object of the present invention to improve existing methods and apparatuses for detecting a tilt tendency of a vehicle.
SUMMARY OF THE INVENTION
A method according to the present invention detects a tilt tendency of a vehicle about a vehicle axis oriented in the longitudinal direction of the vehicle. This is done by determining, for at least one wheel, a variable describing the wheel rotation speed. In addition, at least one variable representing the transverse dynamics of the vehicle is determined. Advantageously, braking torques and/or drive torques are briefly generated and/or modified at least at one wheel as a function of at least one of the variables representing the transverse dynamics of the vehicle. While the braking torques and/or drive torques at the at least one wheel are being briefly generated and/or modified, and/or after the braking torques and/or the drive torques have been briefly generated and/or modified at the at least one wheel, a variable which quantitatively describes the wheel behavior is determined for that at least one wheel, at least as a function of the variable describing the wheel rotation speed of that wheel. At least as a function of the variable ascertained for the at least one wheel that quantitatively describes the wheel behavior of that wheel, a determination is made as to whether there is a tilt tendency of the vehicle about a vehicle axis oriented in the longitudinal direction of the vehicle.
Be it noted at this juncture that when the phase “tilt tendency of the vehicle” is used hereinafter, what is meant is “the tendency of the vehicle to tilt about a vehicle axis oriented in the longitudinal direction of the vehicle.” The phrase “a vehicle axis oriented in the longitudinal direction of the vehicle” is to be understood as follows: On the one hand, the vehicle axis about which the tilt tendency of the vehicle occurs can be the actual longitudinal vehicle axis. On the other hand, it can be a vehicle axis which is rotated through a certain angle with respect to the actual longitudinal vehicle axis. It is immaterial in this context whether or not the rotated vehicle axis passes through the center of gravity of the vehicle. The case of a rotated vehicle axis is intended also to include an orientation of the vehicle axis in which the vehicle axis corresponds either to a diagonal axis of the vehicle or to an axis parallel thereto.
Advantageously, the method for detecting a tilt tendency of the vehicle is used in the context of a method for stabilizing the vehicle, in particular in the context of a method for preventing tipover of the vehicle.
When a tilt tendency of the vehicle is present, advantageously, in order to stabilize the vehicle and, in particular to prevent the vehicle from tipping over, at least braking interventions are performed at least on one wheel and/or engine interventions and/or interventions on chassis actuators are performed.
If the vehicle is behaving, prior to tipover, in highly oversteering fashion and if it is rolling off over the front wheel on the outside of the curve when tipping over, advantageously, in order to stabilize the vehicle, a braking intervention is performed at least on the front wheel on the outside of the curve in such a way as to generate and/or increase a braking torque at that wheel. The slip conditions at that wheel thus change in such a way that only minor lateral forces are transferred, and the tilt tendency of the vehicle and thus the vehicle's tipover risk are reduced.
It has proven to be advantageous that the magnitude of one of the variables representing the transverse dynamics of the vehicle is compared to a threshold value. Detection of whether a tilt tendency of the vehicle about a vehicle axis oriented in the longitudinal direction of the vehicle is present is performed if the magnitude of the one variable representing the transverse dynamics of the vehicle is greater than the threshold value. As a result, the method according to the present invention is activated only in those transverse-dynamic vehicle situations in which a tilt tendency of the vehicle is to be expected.
Advantageously in this context, as one of the variables representing the transverse dynamics of the vehicle, a variable describing the transverse acceleration and/or one describing the yaw rate of the vehicle is sensed using suitable measurement means and/or is ascertained at least as a function of the variables describing the wheel rotation speed.
Advantageously a determination is made, at least as a function of one of the ascertained variables representing the transverse dynamics of the vehicle, as to which wheels of the vehicle are suitable for detecting a tilt tendency of the vehicle about a vehicle axis oriented in the longitudinal direction of the vehicle. Detection of the tilt tendency is performed on the basis of at least one of those wheels, by briefly generating and/or modifying braking torques and/or drive torques at at least one of those wheels. The wheels identified as the suitable wheels are those wheels which are threatening to lift off. The detection according to the present invention of the tilt tendency is consequently performed directly on the basis of the wheels at risk.
The wheels threatening to lift off are normally the vehicle wheels on the inside of the curve. Advantageously, therefore, a determination is made, as a function of a variable which is ascertained from a variable describing the steering angle and/or from a variable describing the transverse acceleration of the vehicle and/or a variable describing the yaw rate of the vehicle, as to whether the vehicle is traveling through a curve, and its nature. At least one of the wheels of the vehicle located on the inside of the curve is selected for detection of a tilt tendency of the vehicle.
It is furthermore advantageous, in ascertaining which wheels of the vehicle are suitable for detecting a tilt tendency of the vehicle and/or in briefly generating and/or modifying the braking torques and/or drive torques at at least one wheel, if the drive concept of the vehicle, i.e., whether it is a vehicle with front-wheel, rear-wheel, or all-wheel drive, is additionally taken into account
Dominke Peter
Leimbach Klaus-Dieter
Schramm Herbert
Wetzel Gabriel
Cuchlinski Jr. William A.
Kenyon & Kenyon
Pipala Edward
Robert & Bosch GmbH
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