Abstract: An anti-skid control system for an automotive vehicle includes a hydraulic pressure source, a wheel brake for braking a wheel, a pressure control valve interposed between the hydraulic pressure source to the wheel brake in order to regulate a hydraulic braking pressure supplied from the hydraulic pressure source and the wheel brake, the pressure control valve being brought into a duty-cycle pressure-increasing mode operation and a pressure-decreasing mode operation for increasing and decreasing the hydraulic braking pressure, respectively. The duty-cycle pressure-increasing mode operation are repeated such that the pressure-decreasing mode operation is established therebetween. A later pressure-increasing mode operation is treated as a succession of the previous pressure-increasing mode operation if a time duration required for the pressure-decreasing mode operation between the previous and later pressure-increasing mode operations is less than a set value.

Abstract: An antiskid braking system for controlling hydraulic braking pressure to alleviate a lock of wheels so as thereby to control a skid of the wheel and alters the hydraulic braking pressure by repeating at least a pressure reducing phase and a pressure increasing phase so as to render the wheels loose to be locked more for a leading period of time from a commencement of antiskid braking control than for a succeeding period of time of antiskid braking control, or otherwise, if the control of hydraulic braking pressure for the gradual alleviation of the wheel lock is performed in consecutive cycles, in the first cycle of antiskid braking control than in any other remaining cycle.

Abstract: A stability control device of a vehicle includes a device for estimating a liability of the vehicle body to a running instability for producing an instability quantity which generally increases along with increase of the liability; a brake device for selectively applying a variable braking force to each wheel, the brake device including a manually controlled pressure source incorporating a brake pedal and an accumulator pressure source; a manual brake sensor for detecting a substantial stepping on of the brake pedal by a driver; and a controller for controlling the brake device so as to variably apply a braking force to a selected one or ones of the wheels for a stability control of suppressing the vehicle body against the running instability based upon the accumulator pressure, the controller controlling the brake device so that a braking force is applied to the wheels based upon the manually controlled pressure source when the stability control is not carried out, wherein, when the substantial stepping on o

Abstract: In an antiskid brake system that increases or decreases a wheel cylinder pressure according to a wheel speed and vehicle speed, an algorithm applied to pressure increase after pressure decrease is improved. A first target pressure increase amount is computed based on the wheel speed and vehicle speed, and a second target pressure increase amount is computed based on a total pressure decrease amount when pressure is decreased. The wheel cylinder pressure is then increased according to the first target pressure increase amount when an elapsed time from the start of pressure decrease to the start of pressure increase, is longer than a predetermined value, and according to the second target pressure increase amount when the elapsed time is shorter than the predetermined value. In this way, increase of slip amount due to excessive pressure increase is prevented.

Abstract: A control method and system for a vehicle anti-lock brake system to provide for recovery from premature activation of the vehicle anti-lock brake system. The control system includes a microprocessor and accompanying components to perform the control method steps of generating an input signal representing a vehicle wheel velocity, processing the input signal to determine a wheel slip duration, comparing the wheel slip duration to a slip duration threshold, generating a premature activation recovery control signal when the wheel slip duration fails to exceed the slip duration threshold, and performing premature activation recovery control of the anti-lock brake system in response to the premature activation recovery control signal.

Abstract: In order to achieve an optimal pressure build-up function in an anti-lock braking control system for automotive vehicles and to maintain the pressure at the optimal point for long periods of time and thus achieve better brake deceleration with greater stability of travel and greater comfort than with conventional ABS control systems, the anti-lock braking control system includes, in addition to the ABS controller and monitoring circuit (3), a pressure function generator (4) which, for each wheel, intermediately stores an intermediate brake pressure value whenever wheel overbraking has been noted. Then, in the pressure build-up phase, the pressure function generator (4) gives off a signal to the pressure modulator in order to increase the wheel brake pressure in accordance with an exponential function.

Abstract: The objective of the present invention is to present a reliable evaluation method for determining whether a moving vehicle is in a stable antiskid control operation or in an unstable antiskid control operation even when there are wheel speed pulsation caused, and a device based on such a method. In the antiskid control apparatuses and the methods of the invention, it is determined that the moving vehicle is in the stable control when the wheel acceleration being generated while the wheel speed is decreasing exceeds a predetermined threshold value, and also determined that the moving vehicle is in the unstable control when the wheel acceleration is below the threshold value. In another antiskid control apparatus and the method of the invention, it is determined that moving vehicle is in the unstable control or in the stable control basis on the changes in the wheel slipping rate with respect to the coefficient of friction between the wheel and a road.

Abstract: Before braking occurs the speed of non-driven wheels is monitored and averaged to determine vehicle speed and an integrator is initialized with that speed. Acceleration is periodically calculated from the vehicle speed, stored in a ring buffer and averaged. The output of a chassis accelerometer is also sampled during the same periods and stored in a similar ring buffer and averaged. Accelerometer bias due to slope or drift is determined as the difference of the two averaged accelerations. The noise level of the accelerometer bias is determined by filtering and rectification. After braking occurs, the accelerometer output is corrected by subtracting the bias and the noise and is then used to continuously update the integrator output to provide an estimate of vehicle speed during braking.

Abstract: To prevent a great variation of a detected wheel velocity for a period of time after a front wheel sensor or a rear wheel sensor for detection of a wheel velocity actually fails until a microcomputer detects the failure, it is determined whether or not an output pulse period of a front wheel sensor is equal to or shorter than a predetermined period. When the output pulse period exceeds the predetermined period, it is determined that there is the possibility that the front wheel sensor may be in failure, thus a front wheel velocity for a predetermined number of control cycles before (a front wheel velocity before the failure) is adopted as a front wheel velocity of the present control cycle. Also, a rear wheel velocity is calculated in a similar manner. For a time after a failure actually occurs until the failure is detected by a microcomputer, driving force control is not started even if other starting conditions for driving force control are satisfied.

Abstract: A method and system for damping wheel speed oscillation during an anti-lock braking event. The method includes the initial step of sensing the wheel speed and determining a wheel slip based on the sensed wheel speed and a vehicle speed reference. Next, the method continues with the step of determining whether the wheel slip has exceeded a predetermined slip threshold. If the wheel slip has not exceeded a predetermined slip threshold, the method performs normal or unmodified anti-lock brake control. If the wheel slip has exceeded the predetermined slip threshold, the method continues with the step of determining whether an acceleration feedback condition representative of a high mu surface has been satisfied. If an acceleration feedback condition has been satisfied, the method continues with the step of increasing brake pressure applied to the wheel from a steady-state level in a step-wise function during acceleration of the wheel before the wheel speed reaches the vehicle speed reference.

Abstract: In the disclosed method and apparatus, the brake fluid pressure in a wheel cylinder is reduced and thereafter it is re-increased so that the braking torque is linearly increased with respect to time due to the anti-skid control and the rate of change of the coefficient of road surface friction with respect to the wheel slip rate is determined while the brake fluid pressure is thus re-increased so that the brake fluid pressure is re-relieved when said rate of change comes below a predetermined threshold.

Abstract: Improvements in vehicle antilock braking systems of the type having an operator controlled master cylinder (11) and a second source (55, 57) of pressurized hydraulic fluid for selectively supplying rebuild pressure after an antilock event are disclosed. The improved system is selectively operable in one of three braking modes, a normal braking mode (119) where braking force is proportional to an operator brake pedal pressure, an enhanced anti-skid braking mode (69) where braking force may be maintained at a maximum nonskid level, and a conventional anti-skid braking mode (71) where braking force follows a cyclic pattern of fluid pressure bleed and build. The system includes circuitry (17, 19, 35, 37, 93, 95) for determining the speed of each wheel and an arrangement (59) operable independently of any vehicle wheels for determining vehicle deceleration. This comparison normally invokes the enhanced anti-skid braking mode.

Abstract: An anti-skid braking system for wheeled vehicles having fluid actuated brakes associated with the vehicle wheels, speed sensors associated with the vehicle wheels and a cyclically operating control device which is responsive to speed signals from the speed sensors to actuate a pressure dump device to periodically release the fluid pressure applied to the brake of any wheel which is determined to be about to lock and to later re-apply the actuating pressure to that brake when the tendency of that wheel to lock has reduced, and wherein the pressure dump phase is arranged to be cancelled during wheel-lock when the aggregate dump time for the current cycle exceeds a limit value based upon a weighted-average dump time of previous cycles.

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: A method and system for modifying anti-lock brake control to a vehicle experiencing drivetrain-induced oscillations. A wheel speed of each of the wheels is sensed to generate a corresponding speed signal. A drivetrain-induced oscillation condition is detected in one of two ways. First, a wheel speed peak count is determined for each of the wheels. A drivetrain-induced oscillation is then detected if multiple peaks occur within a predetermined period of time. Alternatively, a frequency of oscillation for each of the wheel speeds is determined and compared to a predetermined frequency threshold. Upon determining that the vehicle is experiencing drivetrain-induced oscillation during an ABS event, brake pressure is applied to the driven wheels at approximately the same frequency as the frequency of oscillation of the drivetrain-induced oscillation.

Abstract: The present invention relates to an improved antiskid control apparatus for vehicles. When the front wheel on either one of the right and left sides is antiskid-controlled, this apparatus detects whether the road surface is in the condition of split .mu. in which the road surface friction coefficient is different between the right and left wheels by more than the prescribed value. When the road surface is found to have a split .mu. condition, antiskid control should be implemented on the front wheel mentioned above. To control the rise in brake fluid pressure, the other front wheel must then be shifted in whatever direction facilitates control of the threshold value. In other words, even if a wheel does not attain a sufficient coefficient of surface friction, antiskid control is needed to control easily the rise in brake fluid pressure. A large side force is applied continuously to the vehicle, thereby reducing slippage and cancelling the yaw moment.

Abstract: A method for terminating an automatic braking process improves an automatic braking process by assuring that reliable termination of the braking process always takes place. Breaking-off criteria, which are independent of the actuation force of the brake pedal, are provided for the automatic braking process. The variables relating to the dynamics of vehicle movement or the activation time of the automatic braking process, if appropriate also as a function of variables relating to dynamics of vehicle movement, are used as the breaking-off criteria. Thus, automatic braking process is terminated as a function of vehicle behavior. In addition, the gradient of the braking pressure is determined as a function of the activation time and/or as a function of the switch-off criteria when the automatic braking process is terminated.