Using reflectance sensors to automatically calibrate a robot’s motor speeds

Since motor speeds can be slightly different, I’m interested in automating the process of calibrating the motors on a robot.  I’ve done this by hand before but it was a bit tedious and error prone.

Toward this end I stumbled across a description of a robot that used downward facing reflectance sensors to accomplish this.  The robot could calibrate itself by turning each wheel forward and backward while on a sheet of paper that had a black line drawn on it.  It apparently measured the time between detection at various speeds.

Has anyone done this?

Thanks Tom