[JensR]

I've thought about this a lot, for my model grader.

Gyros will be very difficult, since the drift of electromechanical-mini-gyros is going to be difficult to compensate for. At the very least you'd need to combine their data with that from acceleration sensors. Or maybe you could live with correcting the drift manually via the stick.

GPS is going to be virtually impossible at our scales.

Laser would be possible, I guess. My thought was a camera-based system, though.

Another problem is that you need data to feed into the system. How are you going to generate the data describing the desired shape of the terrain? It's not impossible, but another step you'd need to cover.

What I want to do is a simple blade (mouldboard) level control in the sense of an electronic water-level, for the roll and pitch movements of the mouldboard.