Abstract: A wheel speed sensor assembly includes a rotor formed with first and second protrusions arranged circumferentially on the outer periphery thereof in two separate rows at an equal angular pitch. The first protrusions are angularly displaced from the respective second protrusions by half the angular pitch of the first or second protrusions. The sensor assembly further includes a senor having two magnetoelectric devices each opposing the first protrusions or second protrusions. With this arrangement, the differential waveform produced by the sensor has a flat stepped portion between any adjacent rising and falling portions of the differential waveform. The flat portions make the rising and falling portions steeper and shorter. Thus, when the sensor vibrates in the rotational direction of the rotor, the differential waveform is less likely to overshoot the upper threshold or undershoot the lower threshold, which in turn prevents abnormal block pulses from being produced.

Abstract: A wheel speed sensor assembly includes a rotor formed with first and second protrusions arranged circumferentially on the outer periphery thereof in two separate rows at an equal angular pitch. The first protrusions are angularly displaced from the respective second protrusions by half the angular pitch of the first or second protrusions. The sensor assembly further includes a senor having two magnetoelectric devices each opposing the first protrusions or second protrusions. With this arrangement, the differential waveform produced by the sensor has a flat stepped portion between any adjacent rising and falling portions of the differential waveform. The flat portions make the rising and falling portions steeper and shorter. Thus, when the sensor vibrates in the rotational direction of the rotor, the differential waveform is less likely to overshoot the upper threshold or undershoot the lower threshold, which in turn prevents abnormal block pulses from being produced.

Abstract: An improved multiple control circuit is for use with an anti-lock brake control assembly. It includes a plurality of control logic circuits and an output decision circuit. The control circuits simultaneously receive redundant sensor signals representative of wheel speeds and carry out logical operations based upon the input signals to simultaneously transmit redundant command signals to control the brake pressure of the wheels. Such output signals are not directly sent to actuators, such as brake pressure control valves, but are instead sent through the output decision circuit. If the command signals of the control circuits should be different for some reason, the output decision circuit selects and transmits to the actuators the command signals to control the automobile in the safest manner based upon AND logic and OR logic. Each control circuit is connected to a comparator which compares the output signals of the control circuit with those of the output decision circuit.

Abstract: A vehicle-mounted electronic control unit such as an anti-lock brake control unit is connected to a testing device through two serial transmission lines for testing. Upon startup of the control unit, signals are exchanged therebetween. Only if the signal exchange is completed in a predetermined period of time, the control unit enters into a special operation mode for testing. Otherwise, it is controlled in an ordinary mode. In this test mode, the data in the control unit such as a wheel speed are sent to the testing device to be inputted in its test programs. The testing device then gives to the control unit various command signals produced according to its programs. The control unit then sends test signals in response to the command signals to actuators. Thus, when the control unit is in the test mode, the testing device can control the actuators by transmitting command signals to the control unit and thus can test the performance of not only the control unit but also the actuators from various angles.

Abstract: In the system where multiple devices share one circuit by a sequential transmission system, each of the devices is adopted to monitor the transmission from a device one stage before the device which is immediately prior to the device and when a predetermined period of time passes after the transmission from the devices two stages before the device was made, the device is made to start its own transmission without waiting for the transmission from the device immediately therebefore. The transmission control system mentioned above does not fail and the sequential transmission continues even if a part of the devices fails.