| It is essential to vehicle brake safety by detecting basic performance and durableperformance of brake unit. However, anti-lock brake system(ABS) is excluded fromdomestic traditional test-bed of brake unit for automotive vehicles. To solve theproblem above-mentioned, an ABS control system is developed, which can be used asan add-on to the traditional test-bed of brake unit for automotive vehicles. With theimpact imposed by ABS, a more accurate and reliable result can be achieved from thetest-bed.ABS takes over control of the hydraulic pressure whenever a wheel starts to lockup. Sensors continuously monitor wheel speed and send this information to theElectronic Control Unit(ECU). When a wheel starts to lock, the ECU, using thewheel-speed information and programmed data, sends output signals to control theoperation of the ABS valves. The ECU causes the ABS valves to adjust hydraulicpressure supplied to the brake chambers to control braking and prevent wheel lockup.This thesis develops an ABS control system based on PIC18F2580from Microchip.ABS valves is driven by MC33289and DC motor is driven by LMD18200. Pulsewidth modulation(PWM) is used in DC motor control, and then pumps status ismodulated in order to provide the desire amount of pressure. At the MCU, CAN isimplemented by utilizing Enhanced Controller Area Network(ECAN) module inPIC18F2580and a CAN transceiver named MCP2551. A printed circuit board(PCB)is designed with Protel99SE environment and the PCB can replace the ECU in ABS toperfect detection in test-bed of brake unit for automotive vehicles. At PC terminal,where several USB interface is available, USBCAN-II realize protocol conversionfrom USB to CAN, so CAN communication could be completed between PICmicrocontroller and PC. A CAN communication class which encapsulatedfrequently-used functions of the driver provided by USBCAN-II is developed byDelphi. And software can be easier to develop and maintain with the communicationclass. |
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