Pololu 3pi Robot - Manual (Page 41)

Typically, one might use encoders to measure the lengths of the segments. We were able to just use timing on the
3pi, however, because of the 3pi’s power system, which uses a regulated voltage for the motors and produces highly
repeatable results. With a more traditional power system, motor speed would decrease as the batteries discharge, and
a timing approach like this would potentially produce unreliable results. For example, if you were to use a robot with
a more traditional power system, the function you come up with for T when the batteries are freshly charged might
work poorly when they are nearly drained.
Tip: Once you start significantly increasing your maze-solving speed, performance becomes dependent on the
traction of the tires. Unfortunately, traction decreases over time as the tires pick up dust and dirt from the course. Our
fast maze solver needs to have its tires cleaned every few runs or else it starts fishtailing on the turns, which slows it
down and can even cause it to mess up. You can see the effects of this on the second (solution) run of the video (the
tires hadn’t been cleaned recently). You can easily clean the tires by wiping them with a little rubbing alcohol on a
paper towel.
Pololu 3pi Robot User's Guide © 2001–2014 Pololu Corporation
8. Example Project #2: Maze Solving Page 41 of 63