I'm just starting up with a project where the copter has to fly under the ceiling and holding a certain distance ~20cm.
One solution could be, to do that manual or in Standard Alt-Hold mode using barometer. But the much better solution would be to hold a certain height referencing the distance to the ceiling by using a sonar.
Does anybody have experiences in doing that?
Do you think I'll need to setup a new flight mode? "reversed alt-hold" ;)
Thanks for your replies in advance.