Abstract: A system of driving stability control, which is adapted to control valves for opening and closing hydraulic pressure passages between a master cylinder and brake units of wheels and simultaneously controls pressurizing valves and a pressure relief valves so as to supply braking force selectively and independently to the brake units when a specified driving condition is detected, performs the coordinated braking control that, when a specified step-on pressure is detected during execution of the driving stability control, delivers the braking pressure to the brake units according to brake pedal travels as the driving intends simultaneously with reducing the participative degree of the driving stability control so as to ensure gripping force of wheels that brake the vehicle and reduces reduce the participative degree of the driving stability control with an intention of regarding driving stability of the vehicle as important when the vehicle is going to cause a spin.

Abstract: An antiskid brake controller, which can secure a sufficient braking capability, avoid a locked state and maintain high reliability regardless of a road surface state without using a road sensor, includes a detector for detecting respective wheel speeds, a braking force adjustment unit which responds to the application of a brake and an electronic control unit (ECU) for calculating a control amount to the braking force adjustment unit to prevent the locking tendencies of respective wheels.

Abstract: The invention provides an anti-skid controller capable of correctly executing ABS control by accurately estimating a road surface .mu. without using additional sensors. Each wheel speed is detected, and acceleration of the vehicle body in a case where a wheel speed difference between front and rear wheels exceeds a specified value is determined. In this case, by using a change rate within a specified period of time with respect to a wheel speed of one in which wheel speed changing is small as the acceleration, a road surface .mu. corresponding to the acceleration is determined. Corrections regarding turning, bad road travelling, road surface changing, etc. can be carried out, by determining a lateral G based on a speed difference between left and right wheels.

Abstract: A system for a wheeled vehicle includes sensors for determining wheel speed, wheel load and wheel longitudinal driving or braking force of each wheel, and an estimating or controlling unit for estimating a vehicle body speed and/or a road surface friction coefficient from sensor output signals. The estimating unit determines a coordinate pair of a wheel speed value and a longitudinal force coefficient value for each wheel, and plots the coordinate pairs of the individual wheels as a set of points in a plane rectangular coordinate axis. The unit determines a regression line closely fit to the point set and obtains the estimates of the vehicle body speed and friction coefficient from the intercept of the regression line on the coordinate axis of the wheel speed and the slope of the regression line.

Abstract: An antilock braking system employing stress sensors installed in the wheel axle structure of a motor vehicle. The stress sensors measure a road surface frictional force and a braking torque. A parameter calculating means calculates a parameter M from these measured values. An ABS control means terminates a braking pressure reduction process in accordance with the change in the parameter M. Thereby, the system can preclude the locking of the wheel of the motor vehicle even when the brake is suddenly applied, can prevent the braking pressure reduction from being over controlled, and makes possible braking loss minimization.

Abstract: An antilock braking system using stress sensors installed in the wheel axle of a motor vehicle. The stress sensors measure a road surface frictional force, a vertical load, a road surface friction coefficient, a braking torque, and a side force. An arithmetic calculator calculates a parameter value M from these measured values. An ABS controller controls movement process toward a braking pressure reduction mode in accordance with the change in the value M. Thereby, the system can preclude the locking of the wheel of the motor vehicle even when the brake is suddenly applied.

Abstract: A road surface condition determining system for an automotive vehicle equipped with a traction control feature determines, while the traction control is being executed, a first road surface friction coefficient on the basis of a vehicle speed and longitudinal acceleration and a second road surface friction coefficient on the basis of driving torque applied to the driving wheels and selects, as an eventual road surface friction coefficient, either one of the first and second road surface friction coefficients which is larger than the other.

Abstract: Road surface frictional force is sensed by measuring the strain of a tire or the strain in the vicinity of a wheel of a vehicle, and the sensing of the road surface frictional force is part of an antilock braking system in which, cyclically, brake fluid pressure is increased when the road surface frictional force increases in response to increase of the brake fluid pressure and decreased when the road surface frictional force decreases despite increase of the brake fluid pressure and brake fluid pressure is increased again when the road surface frictional force decreases in response to decreasing of the brake fluid pressure.

Abstract: An automobile brake control system, which applies braking force commonly to both driving wheels and restrictively controls the braking force when a specified difference occurs between a wheel speed of the driving wheel and a vehicle speed estimated based on wheel speeds of the front and rear wheels, controls, when the vehicle is traversing a split surface road, the braking force based on a wheel speed of a specific one of the driving wheels which is suffering a road surface frictional coefficient greater than another driving wheel, and corrects the vehicle speed to a lower speed according to a difference in road surface friction coefficients at the driving wheels.

Abstract: In an antilock brake system in which brake fluid that flows out to a low back-pressure reservoir at the time of a reduction in brake pressure is fed into a wheel brake by a motor driving pump without passing through a control valve to thereby gradually increase the pressure, it is possible to increase the brake fluid pressure to a pressure sufficient to prevent wheel lock even if the road surface has a low coefficient of friction. If, at the time of the reduction in brake fluid pressure, a device for estimating the coefficient of friction of the road surface determines that the road surface coefficient of friction is low, the motor is deactuated (or operated at low velocity) so that the pump will not feed brake fluid to the wheel brake (or so that the amount of brake fluid fed from the pump to the wheel brake is reduced).

Abstract: A brake control system for controlling an amount of braking force applied to a wheel of a vehicle running on a surface, comprising a sensor for measuring a speed of the wheel and for providing an output signal indicative of the speed; and a controller, operatively coupled to the sensor, which implements a Kalman filter to estimate an amplitude and location of a peak in a mu-slip curve representative of a coefficient of friction between the wheel and the surface based on the output signal of the sensor, and which controls the amount of braking force applied to the wheel based on the amplitude and location of the peak.

Abstract: A vehicle includes a plurality of axles including front and rear axles on which wheels are mounted at opposite ends thereof, wheel brakes mounted to the wheels, wheel speed detectors for detecting wheel speeds of the wheels, actuators for operating the wheel brakes, and a friction coefficient determining device for determining a friction coefficient of a travel road surface based on detection values detected by the wheel speed detectors. When each of the wheels is braked, the operations of the actuators are controlled such that braking forces are generated only in the wheel brakes in one of the axles at least at an initial stage of the braking, and the determination of the friction coefficient by the friction coefficient determining device is carried out at the initial stage. Thus, the determination of the friction coefficient by the friction coefficient determining device is more facilitated.

Abstract: In order to correctly detect the frictional state of a running road surface, the running road surface is determined as a low-friction road surface, when tire lock is detected by tire lock detection device, and besides a state in which vehicle deceleration obtained by vehicle deceleration detection means is greater than a predetermined value, is shorter than a predetermined time in a period extending from the start of braking until the tire lock.

Abstract: Yaw moment control apparatus is provided for improving the driving behavior of an automotive vehicle tending to oversteering or understeering. The vehicle's velocity, steering angle, measured yaw rate, and lateral acceleration are determined. A yaw controller generates a value representing a desired yaw rate adjustment based on the steering angle, the velocity and the measured yaw rate. An estimated coefficient of friction is calculated based on the vehicle velocity, the lateral acceleration, the measured yaw rate and the steering angle. The estimated coefficent of friction is used by the yaw controller to determined the desired yaw rate adjustment. The mechanism for calculating the estimated coefficient of friction is only enabled while the vehicle is traveling through a curve.

Abstract: An anti-lock braking system for a vehicle having a plurality of wheels, and a braking system that includes a brake for braking at least one of the plurality of wheels and a brake valve for controlling a braking pressure in the brake in response to a brake valve signal, includes a plurality of wheel speed sensors for generating a plurality of input signals. A polynomial processor, in communication with the plurality of wheel speed sensors, generates a control signal based on a nonlinear polynomial function of the input signal. A post-processor generates the Brake valve signal based on the control signal so as to provide cyclic control of the braking pressure in the brake.

Abstract: The invention is directed to an arrangement for controlling a braking force applied to each of front and rear road wheels of a vehicle depending upon a braking condition, with a hydraulic braking pressure supplied to each of the wheel brake cylinders through an actuator. The actuator is controlled by a braking force controller into which output signals of wheel speed sensors are fed. On the basis of the wheel speeds detected by the sensors, an estimated vehicle speed is calculated, and then a varying rate of the estimated vehicle speed is calculated. Furthermore, a wheel speed differential between the front and rear road wheels (or, a wheel slip rate differential therebetween) is calculated. Only when the wheel speed differential (or, the wheel slip rate differential) exceeds a predetermined value, the varying rate of the estimated vehicle speed is compared with a standard rate to estimate a coefficient of friction of the road surface.

Abstract: The present invention pertains to a control circuit for controlling the yawing moment of a vehicle. It is desirable in some special cases to limit the control behavior of this control circuit. The current estimation of the coefficient of friction is used for this purpose according to the present invention; this estimation leads to the determination of a maximum coefficient of friction, which is used to determine a maximum allowable yaw acceleration. The additional torque used to control the vehicle stability is influenced based on the yaw rate.

Abstract: The present invention is directed to an anti-skid control system for controlling a braking force applied to road wheels including driven wheels of an electrically operated vehicle which has an electrical motor for driving the driven wheels. A hydraulic braking pressure is supplied to each wheel brake cylinder through an actuator. The actuator is controlled by a braking force controller into which output signals of wheel speed sensors are fed. A band-pass filter is provided for passing the wheel speeds of the driven wheels having an oscillation property within a predetermined band of frequencies, out of the wheel speeds detected by the wheel speed sensors. And, a coefficient of friction of a road is estimated to be relatively low when the output of the band-pass filter is in a predetermined range of frequencies.

Abstract: An antiskid control system executes a modified antiskid control which strengthens the tendency of the wheel to lock if a vehicle speed is under a predetermined speed and the vehicle is running on a road which has a low coefficient of friction. Antiskid control is also modified with respect to front wheels and is normal with respect to rear wheels in order to avoid an occurrence of vehicle spin. Further, antiskid control is modified with respect to either a front right wheel or a front left wheel. As a result, a stopping distance of the vehicle can be shortened while securing the steering stability of the vehicle.

Abstract: For the determination of the friction/slip characteristics of the tires of a road vehicle which is equipped with an antilock system designed for an individual wheel control, in an initial phase of a controlled braking, only the wheel brake of an individual vehicle wheel is acted upon by brake pressure and the latter is dimensioned so that the result is the initial retardation in accordance with the driver's wish. During this initial test phase of the braking, the absolute brake slip .lambda..sub.B as well as the friction utilization .mu..sub.B linked therewith is continuously determined as soon as, as a result of just the braking of the test wheel, the vehicle retardation z increases no further and/or the braked vehicle wheel is more strongly retarded than corresponds to a predetermined threshold value, the test braking is interrupted and the braking is continued by pressure action on the further vehicle wheels; corresponding test braking phases are carried out in cyclic sequence for all guidance wheels.

Abstract: The invention is directed to an arrangement for controlling a braking force applied to each of front and rear road wheels of a four-wheel drive vehicle depending upon a braking condition, with a hydraulic braking pressure supplied to each of the wheel brake cylinders through an actuator. The actuator is controlled by a braking force controller into which output signals of wheel speed sensors are fed. On the basis of the wheel speeds detected by the sensors, a wheel acceleration of each road wheel is calculated. Also, an oscillation of a relative movement between the front and rear road wheels is determined. And, a coefficient of friction of a road is estimated in accordance with the wheel acceleration and the oscillation. For example, it is estimated that the road is of a relatively low coefficient of friction, when a mean wheel acceleration of all road wheels becomes less than a predetermined standard acceleration, and when the oscillation is caused to exceed a predetermined level.

Abstract: A slip control system determines friction/slip characteristics of tires of a road vehicle equipped both with an antilock system to permit an individual brake pressure control on individual vehicle wheels. The front wheel brakes are connected to a primary output pressure space of the tandem master cylinder, and the rear wheel brakes are connected to a secondary output pressure space of the tandem master cylinder. A first bore stage of a housing of the tandem master cylinder forms a housing-defined boundary of the secondary output pressure space. An inner piston flange movably seals off a pressureless downstream chamber in relation to an inner portion of the first bore stage. An intermediate wall of the housing delimits the bore stage relative to a central bore stage which extends from a third bore stage receiving a primary piston.

Abstract: A method and apparatus for controlling brakes using a reciprocating cut valve actuated by an expander piston that is moved via a crank pin on a crank shaft. The cut valve cuts off caliper pressure and adjusts the volume and pressure of an output hydraulic chamber to effectuate antilock braking. When changing from antilock braking to normal braking, the movement of the expander piston is controlled by repeatedly changing a crank angle of the crank pin during specified time intervals. The rate of increase in caliper pressure can be set according to (1) detected brake operation which is detected from a present crank angle and a target crank angle and (2) the frictional state of the road surface which is estimated from vehicle acceleration/deceleration.

Abstract: A frictional value between a motor vehicle tire and a road surface is determined for use in an ABS system or a traction control system. Various sensors at the automobile ascertain the vehicle speed and the brake pressure at individual wheels. The angular acceleration of the wheel is calculated from the angular velocity thereof. A wheel slip is calculated from the vehicle speed and from the angular acceleration. The dependency of the coefficient of friction is approximated from the wheel slip with a non-linear approximation equation. The current estimation value for the coefficient of friction is estimated with a recursive estimation algorithm from measurement values previously ascertained during a preceding measuring instant.

Abstract: A pedal stroke detector detects the degree of depression of a brake pedal of a master cylinder to determine a road surface friction coefficient. A wheel speed detector monitors the speed of each wheel of a vehicle. A vehicle body speed calculator estimates the vehicle speed from the wheel speed of each wheel and the degree of depression of the brake pedal as detected by the pedal stroke detector. A lock symptom detecting mechanism detects a lock symptom from the estimated vehicle body speed and wheel speed. When a lock symptom is detected, a memory stores the degree of depression. Subsequent movement calculations are based on the larger of the degree of depression for the instant operational cycle and the degree of depression stored in memory.

Abstract: A difference .delta..sub.2 -.delta..sub.1 is formed between the steering angle .delta..sub.2 actually measured and the steering angle .delta..sub.1 calculated from the vehicle transverse acceleration, vehicle speed, and a series of constants. This difference (.delta..sub.2 -.delta..sub.1) is used to displace the working point on the .mu.-slip curve in the direction of an increase of the lateral stability, i.e., toward smaller slip values. Response can be improved by making the displacement also dependent on the rate of change of this difference or the rate of change of the actual steering angle. Preferably no reaction is produced when the difference is below a threshold angle unless one of the rates exceeds a respective threshold.

Abstract: An anti-skid brake system includes at least one wheel speed detecting device for detecting a rotational speed of each of a plurality of wheels separately; a ground friction coefficient estimating device for estimating a ground friction coefficient .mu. based on a rate of change of signals relating to the wheel speeds detected by the at least one wheel speed detecting device; a braking force adjusting device for adjusting a braking force applied to each wheel; an anti-skid control device for controlling the braking force adjusting device to prevent the wheels from being locked in accordance with the ground friction coefficient .mu. estimated by the ground friction coefficient estimating device; a locked wheel detecting device for detecting a number of locked wheels at least based on the wheel speeds detected by the at least one wheel speed detecting device; and an estimation process altering device for altering an estimation process for estimating the ground friction coefficient .mu.

Abstract: A circuit configuration for a brake system comprising an anti-locking control is furnished with circuits which: (1) at a low friction coefficient on either vehicle side, individually control the brake pressure on the rear wheel brakes upon commencement of a control process, (2) after the first entrance of a rear wheel into a stable phase switch to "select-low", and (3) in the select-low control phased if during a predetermined period of time no instability occurs on the non-selected rear wheel, increase the brake pressure on the non-selected wheel in the next pressure build-up phase by a fixed or variable amount. According to a first embodiment, the brake pressure is delivered prematurely into a wheel brake of the rear wheel if the wheel speed falls below a slip threshold if, at the same time, the factual reacceleration is above a threshold value and if another value derived from the maximum value of the filtered wheel acceleration is exceeded.