Abstract: A relaying controller communicates with an external tool through a first communication path based on a first communication protocol and communicates with sub-controllers through a second communication path based on a second communication protocol, thus relaying communications between the external tool and the sub-controllers. The relaying controller includes a rewritable non-volatile memory having predetermined storage areas divided in correspondence with the sub-controllers. The relaying controller transmits, in response to a memory reading request from the sub-controller, a stored data in the corresponding storage area to the sub-controller through the second communication path, and writes, in response to a memory writing request from the sub-controller, a writing data received through the second communication path in the corresponding storage area. That is, the relaying controller executes accesses of the sub-controllers to the non-volatile memory.

Abstract: A light sensing apparatus for different control systems includes a photosensitive element which generates a light current depending on light incident thereto. A pre-circuit connected to the photosensitive element is operative for generating separate basic signals in response to the light current generated by the photosensitive element. Processing circuits connected to the pre-circuit are active simultaneously for converting the basic signals generated by the pre-circuit into conversion-resultant signals having different forms respectively. The conversion-resultant signals are outputted to the control systems respectively. At least one of the processing circuits may include an oscillation circuit which oscillates at a frequency depending on related one of the basic signals generated by the pre-circuit.

Abstract: The anti-skid control system is capable of performing highly reliable anti-skid control through its accurate estimation of the vehicle speed and proper compensatory control even when sharp braking occurs or in the brake fluid pressure control on road surfaces with a low coefficient of friction likely to cause considerable fluctuations in wheel acceleration. The anti-skid control system is provided with a fluid pressure generating device, a fluid pressure controlling device, a wheel velocity detecting device, a standard speed setting device, a fluid pressure controlling mode setting device which sets either the pressure decrease mode or the pressure hold mode when the wheel velocity declines to a level lower than the standard speed and sets the pressure increase mode when the wheel velocity is equal to or higher than the standard speed.

Abstract: The anti-skid control system is constructed with a brake fluid pressure source for generating brake fluid pressure at high and low levers, a switching valve feeding either high pressure or low pressure to the wheel cylinders, a wheel velocity detecting device sensing the driving wheel rotating speed, an acceleration detecting device detecting the vehicle acceleration and a first arithmetic operation device for finding the estimated vehicle speed and the wheel rotating acceleration based on the wheel velocity detected by the wheel velocity detecting device and the vehicle body acceleration detected by the acceleration detecting device. A brake fluid pressure controlling device is provided for increasing, decreasing or maintaining the brake fluid pressure in the wheel cylinders, controlling the switching valve on the basis of wheel velocity, estimated vehicle speed, and wheel rotating acceleration.

Abstract: An anti-skid control system for an automotive vehicle is provided with an actuator which is disposed in a hydraulic circuit between a pressure generator and a wheel brake cylinder. The actuator is arranged to control the hydraulic braking pressure applied to the wheel brake cylinder. In response to a wheel speed detected by a wheel speed detector, it is determined in an electronic control unit whether a condition for decreasing the braking pressure is effected. When this condition is effected, the decrease mode is provided in the control unit. When a predetermined period of time lapses after the decrease mode is initiated, the decrease mode is turned to a pressure control mode for applying the braking pressure to prevent the road wheel from being locked. When the condition is not effected during the predetermined period of time after the decrease mode is initiated, the decrease mode is turned to a direct supply mode for directly communicating the pressure generator with the wheel brake cylinder.

Abstract: The anti-skid control system is provided with wheel velocity sensors only for the driving wheels and yet is capable of performing the anti-skid control through its accurate estimation of the vehicle speed and proper compensatory control even when sharp braking occurs immediately upon the release of the accelerator after the occurrence of acceleration slip. The anti-skid control system is capable of starting the anti-skid control with certainty even when the braking operation is not detected because of a failure in the operation of the brake switch. The system is provided with a fluid pressure generating device, a fluid pressure controlling device, a brake operation detecting device, an acceleration detecting device, a wheel velocity detecting device, a braking force controlling device, a brake force correcting device and an acceleration slip detecting device.

Abstract: A vehicle anti-lock brake control apparatus including a two-position direction control valve disposed between a wheel brake cylinder and a hydraulic pressure source, for increasing and decreasing the brake cylinder pressure, a slip detector for detecting a slip condition of the wheel, a controller for controlling the valve so as to prevent excessive slipping of the wheel, an averaging device for obtaining an average value of the wheel acceleration during a period until the detected slip condition deteriorates to a predetermined reference condition, and a device for determining a pressure decrease time substantially in reverse proportion to the average value of the wheel acceleration obtained when the slip condition has deteriorated to the reference condition, and supplying the controller with the determined pressure decrease time.

Abstract: An anti-skid control system for use in a motor vehicle having wheels whose rotational speeds are sensed by wheel sensors. The anti-skid control system decides the condition of the road-surface, on which the motor vehicle is running, on the basis of signals from wheel sensors. A reference speed is further calculated on the basis of the sensed speeds of the wheels symmetrically provided at the rear-right and rear-left sides with respect to the advancing direction of the motor vehicle. That is a selected one of an average value of the speeds of the rear-right and rear-left wheels sensed by the wheel sensors and the maximum one of the sensed rear-right and rear-left wheel speeds is selected in accordance with the decided road-surface condition. The reference speed is calculated on the basis of the selected one. A control unit of the anti-skid control system performs slip control of the wheels in accordance with the calculated reference speed.

Abstract: The invention is directed to an arrangement for monitoring a road condition which determines the coefficient of friction of the road surface on the basis of a signal corresponding to an acceleration of a vehicle detected by an acceleration sensor. The signal is converted into one of at least two predetermined values by conversion means in response to a magnitude of the acceleration every cycle of a predetermined time period. The converted value is summed up by summing means by a predetermined number of consecutive cycles to provide a total value in the last cycle thereof which is stored in memory means. Then, in determination means, one of at least two standard values is selected in response to the condition of increase or decrease of the total value in the present cycle provided by the summing means as compared with the total value in the previous cycle stored in the memory means.

Abstract: The anti-skid control system is provided with wheel velocity sensors only for the driving wheels and is capable of performing the anti-skid control through its accurate estimation of the vehicle speed and proper compensatory control even when sharp braking occurs immediately upon the release of the accelerator after the occurrence of acceleration slip. The anti-skid control system is capable of starting the anti-skid control with certainty even when the braking operation is not detected because of a failure in the operation of the brake switch. The system is provided with a fluid pressure generating device, a fluid pressure controlling device, a brake operation detecting device, an acceleration detecting device, a wheel velocity detecting device, a braking force controlling device, a first estimated vehicle speed setting device and a second estimated vehicle speed setting device.

Abstract: Sensors detect rotational speeds of respective vehicle wheels. A slip detection reference value is calculated from the detected rotational speeds of the vehicle wheels. Acceptable slip ranges for the respective vehicle wheels are determined in accordance with the calculated slip detection reference value. The rotational speeds of the vehicle wheels are compared with the corresponding acceptable slip ranges respectively. Slip controls of the respective vehicle wheels are performed when the rotational speeds of the vehicle wheels reside outside the corresponding acceptable slip ranges respectively. The highest of at least two of the rotational speeds of the vehicle wheels is selected. Differences between the respective rotational speeds of the vehicle wheels and the selected highest vehicle wheel rotational speed are calculated. The slip detection reference value is corrected in accordance with the respective calculated differences.

Abstract: An apparatus for controlling running of a motor vehicle by measuring respective values of acceleration of the vehicle wheels, includes a digital low-pass filter for obtaining acceleration values by excluding high-frequency noise components of successive values of instantaneous acceleration which are obtained for each wheel at successive sampling intervals. Filter parameters such as the cut-off frequency can be controlled in accordance with the current operating conditions of the respective wheels, such as wheel velocity, to thereby provide optimum filter operation and hence substantially improved accuracy for the derived values of acceleration.

Abstract: In an apparatus for detecting the abnormality of a rotational speed sensor adapted for, for example, an anti-skid control system, a time period within which a subsequent pulse will be generated by the rotational speed sensor in response to the rotation of a body of revolution such as wheel is estimated on the basis of the latest pulse interval of the pulses previously generated therefrom and a value corresponding to the force of inertia of the wheel developed on the braking operation thereof. The determination of abnormality of the rotational speed sensor is made when the subsequent pulse is not produced within the estimated time period. This is arranged based on the fact that the pulse interval depends upon the inertial force of the wheel. With the above arrangement, the abnormality detection of the speed sensor can be quickly made, so that a fail-safe control in a braking system can be speedily performed in response to the occurrence of abnormality of the speed sensor.

Abstract: A cycle time of pulses converted from an electrical signal generated at a rotational sensor is counted. In determining a cycle of the pulses, either a rising edge or a falling edge of the pulse is selected. As the selection of the either edge affects accuracy of the rotational speed measurement, two modes are proposed. One is suitable for a lower speed range in which either of the rising and falling edges is selected for every pulse monitoring period considering the relative phase position of the pulse and the pulse monitoring period. The other is suitable for a higher speed range in which one fixed edge is utilized. Here the edge is selected depending on the winding direction of the electric wire of the pick-up coil of the rotational sensor and independent of the pulse monitoring period.

Abstract: A failure diagnosis system for a vehicle includes a failure detection means for detecting failures of devices or apparatuses installed in a vehicle, a storage means for storing failure information detected by the failure detection means, a failure display means for displaying failure information stored in the storage means, a time information means for adding failure information detected by the failure detection means and stored in the storage means to time information showing the time when the failure information is detected, a retrieval time input means for inputting a retrieval time and a selective display means for displaying selectively failure information which has time information being within the retrieval time.

Abstract: A wheel slipping control apparatus for controlling a braking hydraulic pressure to be applied to a wheel so as to perform an effective braking operation. The wheel slipping control apparatus comprises a control unit for generating a control signal in accordance with the wheel slipping state so as to perform a braking pressure control cycle so that the braking hydraulic pressure is set to a pressure decreasing mode and then to a pressure increasing mode. In the control unit, one of the braking pressure control cycles to be performed is determined as a learning control cycle to obtain a learning pressure-decreased value decremented in the learning control cycle and to obtain a learning pressure-increased value incremented in the learning control cycle.

Abstract: In an anti-skid control system for a motor vehicle there is provided a fail-safe control system for providing a compensation for a proper vehicle braking operation against the occurrence of failure of a hydraulic pressure control valve. The fail-safe control system includes a device for monitoring a control signal for controlling the operation of the control valve so that the hydraulic pressure applied to a wheel braking cylinder is regulated for preventing a wheel of the vehicle from skidding. The monitoring device detects the occurrence of failure of the control valve when the control signal indicative of one of the operation modes of the control valve is continuously generated more than a predetermined time period.

Abstract: Disclosed is an antiskid control system for a vehicle wherein the rotational acceleration of a wheel of the vehicle is detected and the rate of variation of the detected acceleration is detected upon the onset of speed reduction of the wheel. A pressure modulator, which is located in a hydraulic line between a master cylinder and a wheel cylinder, is responsive to the detected rate of variation of acceleration to provide a pressure relief action on the fluid pressurized by the master cylinder and supplies the modulated fluid to the wheel brake cylinder.

Abstract: In an antiskid control system, the acceleration of a vehicle wheel is detected and compared with a predetermined value. A first count value is incremented in response to the detection of the wheel acceleration exceeding the predetermined value. When this first count value exceeds a reference count within a first preset period, the road is interpreted as having a rough surface and a second count value is similarly incremented in response to the detection of the wheel acceleration exceeding the predetermined count. If the second count value does not reach the reference count within a second preset period longer than the first preset period, the road is interpreted as having a smooth surface. The gradient of brake hydraulic pressure of the vehicle is controlled in response to the different interpretation of the road surface.

Abstract: A pulse signal is generated by a wheel speed sensor with a frequency proportional to the speed of rotation of a vehicle wheel, the pulse signal comprising a plurality of frames each having a series of a predetermined number of pulses which are tended to be affected by noise and pulse mutilation. Pulses in each frame are counted and from the count is derived an instantaneous wheel speed value. The difference between the successively derived instantaneous speed values is taken and compared with a predetermined threshold. A first or a second indication is given in response to the difference being lower or higher than the threshold, respectively. If the first indication is given, output signals representing the average wheel speed and average wheel acceleration of the wheel are derived from the instantaneous speed values of successive frames.