I am leading a Micromouse Team for IEEE UCSD, and in trying to hack something together that would drive in a straight line, I ended up making a contrivance with a lot of tape holding it together.  I named it the Tape Monster, because it didn’t really work, and it looked horrible, compared to what I usually produce.

Now, it turns out that there is a preexisting Tape Monster, from before I joined the Micromouse Team in 2008, so my ‘creation’ is technically the Tape Monster mkII.  Fair enough, I guess.  Anyways, the robot has 4 Sharp GP2D120X sensors, an Arduino board, motor driver shield and a pair of DC motors with encoder feedback on them.  I wanted to power the thing from the USB port, but the cable bias was unacceptable, so I added some batteries.

Here’s where things get interesting.  Without encoder feedback based speed control, the value of Vin (feeding the H-bridges that drive the motor) matters.  The reason is that the higher Vin is, the PWM duty cycle required to overcome the parasitics of the motor is reduced.  Do I have equations a sexy graph for this?  No,  I wanted my robot to drive straight, NOW.  I would like to relate them, but that will have to wait for a night when I’m not under a massive time crunch.

You can follow the progress of my robot and see some of the data that I am using to drive my engineering and design decisions at the IEEE UCSD Wiki.

Now back to the regularly scheduled homework assignment….