Abstract: An electronic control unit includes a microcomputer and an input interface circuit. The microcomputer has square wave input ports, a reference square wave input port, a serial communication port, and an output port. Square wave signals are inputted from sensors to four channels of the input interface circuit. A channel selector included in the input interface circuit the selects square wave signals in orderly sequence for capturing. The microcomputer performs a comparison between a time at which the square wave is captured and a time at which the selected square wave signal is captured for diagnosing operation of an input capturing function.

Abstract: An ECU (100, 200) includes a monitoring circuit (2) having a counter (3) for selecting an assignment number (21) of an assignment signal (20), a serial communicating unit (4) for transmitting the assignment signal (20) of the assignment number (21) selected by the counter (3) and to and receiving an answer signal from a microcomputer (1). The ECU also includes a comparing/judging circuit (5) for comparing an answer number (11) with a correct answer number (30) and incrementing the assignment number (21) of the assignment signal selected by the counter (3) by one when both the answers match. This circuit (5) maintains the same assignment number (21) when the answers do not match. The microcomputer (1) performs the operation in conformity with the assignment number (21) of the assignment signal (20) received and transmits the operation result by using an answer signal (10).

Abstract: An ECU (100, 200) includes a monitoring circuit (2) having a counter (3) for selecting an assignment number (21) of an assignment signal (20), a serial communicating unit (4) for transmitting the assignment signal (20) of the assignment number (21) selected by the counter (3) and to and receiving an answer signal from a microcomputer (1). The ECU also includes a comparing/judging circuit (5) for comparing an answer number (11) with a correct answer number (30) and incrementing the assignment number (21) of the assignment signal selected by the counter (3) by one when both the answers match. This circuit (5) maintains the same assignment number (21) when the answers do not match. The microcomputer (1) performs the operation in conformity with the assignment number (21) of the assignment signal (20) received and transmits the operation result by using an answer signal (10).

Abstract: An electronic control unit includes a microcomputer and an input interface circuit. The microcomputer has square wave input ports, a reference square wave input port, a serial communication port, and an output port. Square wave signals are inputted from sensors to four channels of the input interface circuit. A channel selector included in the input interface circuit the selects square wave signals in orderly sequence for capturing. The microcomputer performs a comparison between a time at which the square wave is captured and a time at which the selected square wave signal is captured for diagnosing operation of an input capturing function.

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: 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: 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.