FEZ Mini Robot, simple odometry

For solving a line maze are provided with two reflectors insufficient. For this I want multiple sensors via I2C bus. The two reflectors can easily be used for odometry.
The inside of the wheels is a hard disk of white paper pasted.
The sensors are positioned with the holes in the wheels and can see the transitions from black to white disc wheel frame and back wheel is a pulse counter. The software is a histeresys used to avoid double counting.
Through the eight holes are 16 transitions per wheel rotation, the accuracy is therefore circumference (21 cm) divided by 16 is about 1.3 cm
For a line maze with a grid of 15 cm seems to me plenty, you can use the calculated distances for each node to synchronize with the grid

This is a very smart idea!

That is indeed a smart idea which was used a couple of time in other robots on the internet.
Thanks for making it clear ;D

@ Robert, for proper operation, the sensors connected to the pin AN2 and AN3, this allows the possibility interrupt pin used. The processing of the wheel sensor is integrated into the “engine module”. This gives the opportunity to “move routine” not only speed but also the distance as a parameter to this function.
Controlling the distance traveled by the interrupt routine done.
Because two motors are never quite the same I am now working on a calibration routine for the motor so they really coincide.