Abstract: An instability value for at least one wheel is derived from the detected variables such as rotational velocity of the wheels, and as a function of this instability value, the brake systems are actuated to change the brake pressure, such that in addition, the present invention can calculate a variable which modifies or represents the driving dynamics of the vehicle and wherein the instability value can be modified as a function of the calculated driving dynamics variable.

Abstract: Wheel speeds on each side of the vehicle are added, and the sums are subtracted to form a difference VXU which is time filtered to produce a filtered difference VXG. As long as VXU does not exceed VXG by more than a speed dependent threshold, a signal indicating straight line travel is produced. This signal can be cancelled when VXG exceeds a vehicle dependent threshold and is also blocked when the vehicle speed falls below a minimum, when the ABS is operating, or when the vehicle is decelerating. The signal indicating straight line travel accounts for tire tolerance and can be used to control vehicle dynamics, for example by preventing an increase in brake pressure or engine braking when the vehicle is travelling in a curve.

Abstract: A brake system is described which calculates the duration of the pressure reduction signal. In this case, the wheel acceleration (or the wheel reacceleration) and the slip are determined in the unstable region of the wheel and related to prescribed magnitudes, from which the calculation of the reduction time of the new control cycle is performed in such a way that the wheel reacceleration following the pressure reduction corresponds to a precalculated magnitude. This signal duration is corrected in order to keep the amplitude of the pressure modulation small.

Abstract: In an anti-lock braking system in which pressure is reduced in pulses separated by pressure maintenance phases, the duration of the first maintenance phase is dependent upon the vehicle deceleration and the wheel slip. A second pressure reduction pulse is triggered only when the wheel acceleration is less than a predetermined low threshold.

Abstract: A vehicle brake system is described in which a lower brake pressure is fed in at the rear axle compared with the brake pressure of the front wheels. For the purpose of feeding in this brake pressure, the difference VD between the fastest front wheel speed and the slowest rear wheel speed is formed and compared with a threshold value which depends on the vehicle deceleration. An increase in pressure is undertaken until the threshold value is reached. The threshold value is, furthermore, larger in the case of travel in a straight line than it is in the case of travel in a curve.

Abstract: An anti-lock brake system is described in which, when an instability limit IS is exceeded by an instability criterion KK=aB+b.multidot.L+cIL+dV.sub.F(where a, b, c and d are constants and B is the relative wheel deceleration, L is the wheel slip and IL is the integral of the wheel slip and V.sub.F is the calculated vehicle deceleration, a pressure reduction pulse is produced, the width of which depends on the reduction time in the preceding cycle. This pulse also resets the integrator and the differentiator required for obtaining the wheel deceleration to 0. Between the pressure reduction pulses, pressure is held constant.

Abstract: The reference speed required for slip development is formed by using an auxiliary reference which specifies the reference slope during a sudden drop in wheel speed. In other circumstances, the speed of the second fastest wheel is included in the forming of a reference during the control action. In the absence of ABS control, the average speed of the non-driven wheels determines the reference speed. The change of reference speed forming from average value to use of the slope of the auxiliary reference and the speed of the second fastest wheel is made both at commencement of control action and even independently control action, when the sum of all wheel slips exceeds a threshold value a.