Abstract: A signal conditioning circuit is provided for a plurality of pressure signals generated by individual pressure sensors mounted upon a hydraulic control valve. The signal conditioning circuit sequentially samples each of the pressure sensors and multiplexes the individual pressure signals into a single analog pressure signal. The signal conditioning circuit includes a differential amplifier that is compensated for offset and linearity as a function of which particular pressure sensor is being sensed.

Abstract: A plurality of pressure sensors are carried in housing mounted upon a hydraulic control valve for an electro-hydraulic brake system. The pressure sensors are electrically connected to a signal conditioning circuit which also is mounted upon the hydraulic control valve. The signal conditioning circuit samples the sensors and mulitplexes the sensor signals into a single output signal.

Abstract: An electronic brake management system for controlling the application of fluid pressure to the brakes associated with wheels on a vehicle is disclosed. The system comprises a plurality of hydraulic valves for controlling the application of fluid to the brakes and a plurality of valve drivers for controlling the valves in accordance with respective electrical control signals for the plurality of valves. The system further includes a valve pulse width modulation controller for generating the respective electrical valve control signals applied to the valve drivers. The electrical valve control signals from the pulse width modulation controller are modulated to reduce the amount of electrical power supplied by the individual ones of the electrical signals once the valve associated with the one of the electrical signals has changed its opening to a desired position.

Abstract: Test signals are generated by a microcontroller (i.e., micro) and coupled to a transistor which is in series with an inductive sensor of a wheel speed sensor input circuit to test the input circuit. In one test, a test signal from the micro sweeps through a range of predetermined frequencies to turn the transistor off and on to provide a simulated wheel speed signal which is used to compute a corresponding number of simulated wheel speeds. The programmed micro compares the simulated wheel speeds with the predetermined frequencies to determine if the various components of the circuit are operating properly and also to determine if the wheel speed arithmetic of the programmed micro is operating properly since actual wheel speed routines within the micro are used to compute the simulated wheel speeds.

Abstract: Test signals are generated by a microcontroller (i.e., micro) and coupled to a transistor which is in series with an inductive sensor of a wheel speed sensor input circuit to test the input circuit. In one test, a test signal from the micro sweeps through a range of predetermined frequencies to turn the transistor off and on to provide a simulated wheel speed signal which is used to compute a corresponding number of simulated wheel speeds. The programmed micro compares the simulated wheel speeds with the predetermined frequencies to determine if the various components of the circuit are operating properly and also to determine if the wheel speed arithmetic of the programmed micro is operating properly since actual wheel speed routines within the micro are used to compute the simulated wheel speeds.

Abstract: A method and apparatus for detecting the proper functioning of an ABS control unit which utilizes dual programmed microprocessors, the second of which calculates mismatched wheel speed and both of which calculate extended control loop time. When computed wheel velocities are above 10 mph, the second microprocessor determines whether the difference in computed wheel velocity between the two microprocessors is at least 2 mph. If the difference is more than 2 mph for more than 6 consecutive program loops, a mismatched wheel speed calculation error is identified. Each of the microprocessors also compares its loop timing with the loop timing of the other microprocessor and if more than 1 millisecond late for 6 consecutive program loops, the proper diagnostic response is to set an ignition latch code which triggers an inhibit signal. In addition, if the first microprocessor determines more than a 16 millisecond delay, then the first microprocessor is reset.