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Carbot

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  • bill rowe
    Carbot is one of my original inspirations for the Olduino project. The original was an arduino-based wall racer that I built a couple of years ago. It
    Message 1 of 1 , Dec 28, 2013
    Carbot is one of my original inspirations for the Olduino project.  The original was an arduino-based wall racer that I built a couple of years ago. It originally had a wired remote control but I removed that and replaced it with an arduino, a motor controller and two ultrasonic range finders - one facing forward and one to the side so it could whip around an arena keeping a specified distance from the wall on its right. Steering is done by controlling the rear wheels independently.

    The picture shows the olduino hardware stack on board the car chassis with just the front sensor plugged in.  It's tall obviously but it looks like everything will fit well enough mechanically and I can start on the software.

    The arduino controlled the wheels with "analogWrite(x,y)" this starts a 10 khz pulse train on pin x with duty cycle y(this is called Pulse Width Modulation).  To drive the left wheel forward at half speed the arduino would issue "analogWrite(Fleft,50); analogWrite(Bleft,0);"  where Fleft and Bleft are connected to the motor control for the front wheel - to run backwards it would be 0 and 50.  

    Without hardware PWM the olduino will have to bitbang the motor control pins in the same loop that polls the sensors. The measurement time should be on the order of a few ms so hopefully I can start with:
    -measure front sensor
    -measure side sensor
    -adjust driving parameters(what duty cycle the motor controllers will see for each wheel)
    -drive for 100 ms(something like .2m)
    -repeat

    I've tried out the rangefinder before(http://groups.yahoo.com/group/cosmacelf/message/10774) but this will be first time out for the motor control



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