Lego Mindstorms Orientation

The Lego Mindstorms RCX is a great platform for experimenting in machine vision. While the IR tower used to connect to ver. 2.0 and below is somewhat limiting in distance it is strong enough to provide an interesting platform for experimentation.

In any mobile robot project the orientation of the robot is important to know as motor commands need to be based on the current robot configuration. As an example of what is possible we set out to create a technique that will determine when the Lego Mindstorm is pointing directly toward the camera. The setup requires an external USB camera that is statically mounted in view of the Lego Mindstorm's RCX brick. We chose the tracked Roverbot as a simple example.

First we need to detect the Lego Roverbot...