Since things like this often seem to show up here, people interested on a self-balancing robot might want to check out the November, 2016 of Circuit Cellar Magazine. They have an article in there on how to do it - they use a different processor (PIC 32), however, lots of good info on the sensors and how to accomplish the task. You would have to figure out how to accomplish the tasks with an arduino, but that is part of the fun! Hope this helps someone looking to do that task.
Just curious: what kind of regulator(s) do they use?
They indicate they are currently powering it with a power supply but note that a battery pack would provide freedom of movement. They also discuss the PID control loop and how it works.
Thanks, I wanted to know wheter it's a PID or a more sophisticated controller.
I've seen various videos about balancing projects, with very different response times an overshoots, so that I suspect that really good results can not be achieved by PID.
They indicated that at a 50 hz update rate for the PID, it was not very stable, but at 100 hz, they had much better response. The article was worth a read (as is the rest of the magazine - one of the few left that has fun projects in it).