Method and apparatus for preventing vehicle handling instabilities

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.