I have a 3DR HexaCopter with the 880kV motors. With the default settings across all PIDs, the copter lands without bouncing. When I set the Rate D for Pitch/Roll just a hair higher ( .007 where the default is .005 ), the copter has a hard time staying on the ground when coming in for a landing while the flight mode is in Acro or Stabilize. On the ground and bringing the throttle stick all the way down, the copter will actually increase throttle causing a 1/3 meter bounce.
As far as wanting to set the Rate D for Pitch/Roll higher, I've been attempting to follow the Arducopter Tuning Guide post by Dave C. It seems Rate D for Pitch/Roll for my copter ought to be a little higher according to the article.
Replies
I should also mention that you shouldn't get too hung up on actual tuning numbers of others.
I have small quad that I can't get anymore than 0.008 rate_D into it, therefore rate_P of no more than 0.15 but my tri is very happy at 0.02 and 0.250 respectively. The figures you end up with will be specific to your setup.
The way I land - it may not be correct, but it works, is to switch to alt hold mode a few feet up, then throttle down and the copter settles to the ground gently, then switch to stabilize mode and the props stop.
Yes, this is an issue.
The way I handle it right now, is that I put the quad a few inches above the ground, get it level, and then just shut the motors right down. It will fall gently, and not bounce.
Maybe we'll be able to figure out an algorithm, but this is a tough one, as the code doesn't know when you're landing in stab mode.