Method and apparatus for preventing vehicle handling instabilities
First Claim
1. A method of preventing handling instabilities in a motor vehicle, comprising the steps of(a) forming a vehicle yaw angular velocity required value from measured quantities in a means for computing,(b) supplying the computing means with at least one sensor signal from which an actual value of vehicle yaw angular velocity is formed,(c) forming a difference between the yaw angular velocity required value and the yaw angular velocity actual value in the computing means by subtracting the yaw angular velocity actual value from the yaw angular velocity required value,(d) forming a time derivative of the difference in the computing means,(e) forming at least one output signal in the computing means from the difference and as a function of the time derivative to represent one of a detected handling situation and the yaw behavior of the motor vehicle and to contain information on vehicle understeering and oversteering,(f) wherein, based upon a determination of at least one of oversteering and understeering in steps (a)-(e) above, in vehicles with driven rear wheels, the required changed lateral guidance force is deduced, for both oversteering and understeering, when drive slip occurs and, for oversteering when an engine braking torque occurs, and, in vehicles with driven front wheels, the required changed lateral guidance force is deduced, for both oversteering and understeering, when drive slip occurs and, for understeering, when an engine braking torque occurs, such that the motor vehicle is handled with minimum instability by selectively braking and accelerating individual wheels, and(g) varying a slip threshold value in a direction toward zero in the computing means when an analysis of the at least one output signal deduces that a changed lateral guidance force is required on drive axle wheels of the motor vehicle, such that control systems of the motor vehicle are operative to reduce said threshold value when drive slip occurs and increase said threshold value when an engine braking torque occurs.
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Accused Products
Abstract
A method and apparatus for preventing vehicle handling instabilities, in which a vehicle yaw angular velocity required value (μsoll) is formed from measured quantities (vehicle velocity, steering wheel angle). The vehicle yaw angular velocity actual value (μist) is formed from at least one sensor signal, the difference between the yaw angular velocity required value (μsoll) and the yaw angular velocity actual value (μist) is determined by subtracting the yaw angular velocity actual value (μist) from the yaw angular velocity required value (μsoll), and the handling situation or the vehicle yaw behavior to be detected is determined from this difference. The time derivative of the difference is formed to determine whether the vehicle exhibits understeer or oversteer. The slip threshold value (σsoll) is varied in the direction of the value 0 when it is deduced from the detected handling situation that a changed lateral guidance force is required on the wheels of the vehicle driven axle.
49 Citations
14 Claims
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1. A method of preventing handling instabilities in a motor vehicle, comprising the steps of
(a) forming a vehicle yaw angular velocity required value from measured quantities in a means for computing, (b) supplying the computing means with at least one sensor signal from which an actual value of vehicle yaw angular velocity is formed, (c) forming a difference between the yaw angular velocity required value and the yaw angular velocity actual value in the computing means by subtracting the yaw angular velocity actual value from the yaw angular velocity required value, (d) forming a time derivative of the difference in the computing means, (e) forming at least one output signal in the computing means from the difference and as a function of the time derivative to represent one of a detected handling situation and the yaw behavior of the motor vehicle and to contain information on vehicle understeering and oversteering, (f) wherein, based upon a determination of at least one of oversteering and understeering in steps (a)-(e) above, in vehicles with driven rear wheels, the required changed lateral guidance force is deduced, for both oversteering and understeering, when drive slip occurs and, for oversteering when an engine braking torque occurs, and, in vehicles with driven front wheels, the required changed lateral guidance force is deduced, for both oversteering and understeering, when drive slip occurs and, for understeering, when an engine braking torque occurs, such that the motor vehicle is handled with minimum instability by selectively braking and accelerating individual wheels, and (g) varying a slip threshold value in a direction toward zero in the computing means when an analysis of the at least one output signal deduces that a changed lateral guidance force is required on drive axle wheels of the motor vehicle, such that control systems of the motor vehicle are operative to reduce said threshold value when drive slip occurs and increase said threshold value when an engine braking torque occurs.
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8. An apparatus for preventing handling instabilities in a motor vehicle, comprising
(a) computer means for forming a vehicle yaw angular velocity required value from measured quantities, (b) means for supplying the computer means with at least one sensor signal from which an actual value of vehicle yaw angular velocity is formed, said computer means forming a difference between the yaw angular velocity required value and the yaw angular velocity actual value by subtracting the yaw angular velocity actual value from the yaw angular velocity required value and to form a time derivative of the difference, said computer means forming at least one output signal from the difference and as a function of the time derivative to represent a detected handling situation and the yaw behavior of the motor vehicle and to contain information on vehicle understeering and oversteering, (c) means operatively associated with said computing means for varying a slip threshold value in a direction toward zero when an analysis of the at least one output signal deduces that a changed lateral guidance force is required on drive axle wheels of the motor vehicle, such that said slip threshold value is reduced when drive slip occurs and is increased when an engine braking torque occurs, and (d) means for changing the lateral guidance force in response to the at least one output signal in a motor vehicle with driven rear wheels if the required changed lateral guidance force is deduced, for both oversteering and understeering when drive slip occurs and for oversteering when an engine braking torque occurs, and for changing the lateral guidance force in a motor vehicle with driven front wheels if the required changed lateral guidance force is deduced, for both oversteering and understeering when drive slip occurs and for understeering when an engine braking torque occurs.
Specification