Boe-Bot Calibration Test

In the first, brief Boe-Bot video, the servos were about all that was hooked up. So we saw the CPU send pulses through a couple of the pins, which told the servos to rotate.

Now, we see the first video of the Boe-Bot moving by itself. This entails a lot of repetitive calibration -- adjusting the pulse frequencies and the number of pulses to send to each wheel to get the bot to move forward in a straight line and to do simple turns. So, one has to take a guess, program it in, load it into the robot, then move the robot to a smooth surface, align it, and see if it moves in a straight line. If it doesn't, go back to the computer, hook the bot back up, and lather, rinse, & repeat.

This took a while to get mostly straight lines and close to 90 degree turns. By that point, the batteries were starting to weaken -- and that affects how the servos run and how straight the lines traveled are or the angle of the turns. I got it pretty satisfactory one night then had to go to bed. When I came back to it a couple of days later I found it was no longer going straight over a couple of feet or making crisp turns; so I started calibrating again. In the course of 30-60 minutes of recalibrating, the behavior changed again and reverted to values close to -- but not exactly -- what they were previously. Needless to say, this gets a little frustrating.

Also, due to the increased drag of carpet, the calibrations on a smooth lineoleum or tile floor won't be the same as on carpet. This means -- you guessed it -- more calibration! I chose the kitchen floor since it had long tile lines against which to judge straight lines and right angles. After seeing the bot's behavior change within about 10 minutes during calibration as mentioned above, I decided I would not spend time trying to do dead reckoning or precise distance/angle/speed calculations on the bot. Without a more stable voltage supply or some independent way of calibrating the wheel movements, it seemed like it would be time wasted.

Don't worry, I wouldn't presume to make you watch the boring repetition process. But here's about 30 seconds of the boe bot doing it's version of a close-order drill.