That looks very clever and it seems to work perfectly. Great job.

One detail that I did not see explained is the encoder disk you used for the optical sensors. You might say some things about how you arrived at the number of holes that you used and how you located and drilled the holes. I would think that any roughness or fuzz on the edges of the holes may make the readings erratic. Did you have any trouble with that? Did you do anything special to clean them up?

I know this is a wood project, but I would have been tempted to make that disk from metal (aluminum) or plastic.