rear wheel controlleranti lock brake system normal

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Unformatted text preview: ar wheel controller/anti-lock brake system Normal operation Regulate velocity of rear wheel Brake pressed Gradually increase amount of breaking If skidding (front wheel is moving much faster than rear wheel) then temporarily reduce amount of breaking brake pedal pressed Inputs Brake pedal Front wheel speed Rear wheel speed brake on/off micro controller front wheel velocity move rear wheel rear wheel velocity Outputs Pulse-width modulation rear wheel velocity Pulse-width modulation brake on/off * / . 0 1 ) 2 + # Check if brake pedal pressed – or interrupt Move rear wheel write (rearWheel, onOff) Use automatic detection capability of processor brake pedal pressed rear wheel velocity $ Brake pedal port How often? Need to make sure not to forget to do so (use timer) write (brakePort, onOff) GPIO port 3 Software must repeatedly check brakePressed = read (brakePedalPort) Turn brake on/off front wheel velocity , micro controller GPIO port brake on/off move rear wheel Connect brake pedal to input capture or external interrupt pin Interrupt on level change Interrupt handler for brake pedal brake pedal pressed GPIO port micro controller 2 #$ %& $ + ) / ) $ $ Use timer to turn brake on and off To pump the brakes gradually increase the duty-cycle (ton) until car stops Apply brake Set timer to interrupt after “on” time Disengage brake Set time to interrupt after “off” time Repeat How do we tell which interrupt is which? t t t set timer to go off at each edge...
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This document was uploaded on 04/04/2014.

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