Abstract: In an antiskid control system for the hydraulic braking system of a wheeled vehicle, the rotational speed of a vehicle wheel and the acceleration of the wheel are detected and levels of road surface friction are determined on the basis of the wheel speed and acceleration to give a first indication that the road has a high value of friction or a second indication that the road has a low value of friction. The wheel speed and acceleration are analyzed to detect a down-pressure mode to decrease the fluid pressure of the braking system and an up-pressure mode to increase the pressure. In response to the presence of the first indication, the down-pressure mode is effected at a lower rate and then at a higher rate. In response to the occurrence of the second indication, the down-pressure mode is effected at the higher rate.

Abstract: In an antiskid control system for a motor vehicle, the speed and acceleration of at least one vehicle wheel are detected, and from the detected wheel speed, the speed of the vehicle is estimated. First and second variable threshold values are derived from the vehicle speed. The wheel speed and acceleration are compared with the first and second thresholds, respectively, to estimate the level of road surface friction and to operate solenoid-operated hydraulic brake pressure decreasing means. The operating period of the pressure decreasing means is controlled in accordance with the estimated road surface friction to prevent excessive reduction of the brake pressure and premature locking of the wheels.

Abstract: In an antiskid control system the speed of a vehicle wheel is compared with a variable threshold which is a function of the speed of the vehicle and a first comparator output is generated when the speed is lower than the variable reference. The acceleration of the wheel is compared with a predetermined threshold for generating a second comparator output when the acceleration is lower than the threshold or a third comparator output when the acceleration is higher than the threshold. The fluid pressure of the braking system is lowered in response to there being a simultaneous presence of the first and second comparator outputs and raised in response to there being a simultaneous presence of the first and third comparator outputs.

Abstract: In an antiskid control system, first and second wheel speed values are derived from pulse signals supplied from wheel speed sensors to indicate respectively the rotational speeds of first and second wheels of the vehicle. A trimming value is derived from the difference between the first and second wheel speed values and used as a multiplier by which the first wheel speed value is multiplied to compensate for the deviation of the speed of the first wheel with respect to the speed of the second wheel. The compensated first wheel speed value compared with a variable threshold that is a function of the speed of the vehicle to determine the down pressure timing.

Abstract: A diagnostic monitoring system, for detecting and displaying malfunctions or abnormal operations occurring in various engine operation control computers, includes a microcomputer, actuators and sensors. Each of the engine operation control computers performs a diagnosis program as a part of their control programs and produces a signal whenever a malfunction or abnormal operation is detected. A central supervisory system receives such signals from the engine operation control computers and stores them separately for the individual control computers. A display unit displays the stored signals in response to instructions from the central supervisory system.