Similar to my first turtle, this robot is designed to draw shapes on a piece of paper. The difference is that this version was built with only parts from the Robotics Invention System. Surprisingly, it is able to draw much more accurately than the first one. There are quite a few tricks used in this robot to get three functions from two motors, and enable perfectly straight driving.

The virtual model. The light sensor is used as a rotation sensor to measure distances and turning angles.

Okay, that's enough. Buy the book when it comes out!