New DJI F550/Naza RTH - rough landing

[nicheuser]

Hi guys,

I just got my new F550 assembled, configured, and flying quite well, and I have a newbie question for anyone who's been there. I tested the return-to-home function for the first time today, and it works great, but I found the landing itself almost comical. It slowly lowered itself toward the ground and then "bounced" off the ground by smacking into the concrete and then flying back up to about 3 or 4 feet high, and it repeated this act around 5 or 6 times before finally landing and shutting off the motors. The GPS receiver was locked in on at least 6 satellites, but I would guess that GPS altitude accuracy was at least partly to blame. I'm curious whether this is normal, and whether anyone has any suggestions on how to make it land itself better than this. There was an altitude gain setting in the software that I didn't touch because I wasn't sure I needed to--could that be related? The 6-bounce landing was not a problem today because I don't yet have a gimbal with a camera installed, but when I do, I'll want a much more gentle landing. I'm asking only for demo purposes, because in reality, I would always switch back to manual control and land it myself. :-)

Ideas? Thanks!

--Kris

[Wesley888]

That bouncing is a very very very common problem. I did not follow those discussions to see how they fixed it though. Mine worked perfectly even the first time.

See if you can find anything in this monster thread: http://www.rcgroups.com/forums/showthread.php?t=1536553

[R_Lefebvre]

Wesley, I didn't know the DJI had this problem? I thought it was only Arducopter?

Ground detection is a difficult thing without having an actual ground contact sensor.

[Wesley888]

My Hexa with DJI NAZA worked flawlessly right out of the box, so do many people that I've met in the forum. It detected ground very nicely and landed gracefully. Remember this?

[ame]http://youtu.be/MAHfgxZyViU[/ame]

It also worked great on hard ground in case you wonder. (You can hear it landed and shut off the motor even though you can't see it in the following video at the end)

[ame]http://youtu.be/Zec8HFPCbsQ[/ame]

Just that, every so often, I've saw forum thread about the same bouncy problem. It just happened to a few and nobody knew how to fix it at that time. I just briefly browsed those forums and don't see those problem being reported any more. Maybe people have found the solutions.

[Wesley888]

Originally Posted by nicheuser

. It slowly lowered itself toward the ground and then "bounced" off the ground by smacking into the concrete and then flying back up to about 3 or 4 feet high, and it repeated this act around 5 or 6 times before finally landing and shutting off the motors

I have an idea. Go to the Motor Mixer tab and change the Motor Idle Speed to the lower setting(s). Try different one out.

Another thing you can try is to temporary use some tapes to tape around the NAZA unit. Someone suspected that light or air (or some mysteries force) got into the NAZA unit and made it do that. Try that out as well.

[nicheuser]

Hi Wesley,
Thanks for the suggestions. Two things I think I'll try: 1) launching from the grass so that it will return and land in the grass. When I tried it before, it was on pavement, so maybe that's part of the problem. 2) I'll play with the motor idle speed as you suggested. Right now, it's on the recommended middle setting. As I said, in the future, I will take over and land manually as soon as it gets close, but as an engineer, I'd like to find the cause and fix it anyway. :-)
--Kris

[pblgml]

You may want to put a piece of black tape on the left side of the NAZI. Light will affect the barometer and give if a false indication of altitude. I have read this in several forums and noticed it one day while flying at about 60 feet it dropped quickly and then climbed back up just as quickly. I immediately turned the left side away from the sun and it stopped. I landed and placed a piece of black tape on the NAZI and went and attempted the same flight and never had the problem again.

[Wesley888]

I have read about that as well. Do try that out.

[nicheuser]

Thanks guys, I feel like I've heard something like that before, so I'll definitely try it out. At the moment, my F550 is torn down while waiting for my LEDs to arrive, so as soon as I get those installed, I'll try these things and report back.

[nicheuser]

Okay, I tried it again, but this time I'm landing in grass and I've got the black tape on the left (port) side of the Naza. It definitely worked better (

DJI F550 w/Naza M (0 min 39 sec)

), but there was still a good bounce. I tried it again a couple hours later when it was much less sunny, and this time the bounce was much less pronounced (

Return-To-Home Test (1 min 54 sec)

), so maybe it has something to do with the bright sunlight. I dunno, I'm just happy that it can find its way home if it gets out of range--a perfect landing would just be gravy.

[Wesley888]

Go to the Motor Mixer tab and change the Motor Idle Speed to the lower setting(s). See if that can eliminate that tiny bounce as well.

[R_Lefebvre]

That looks pretty good to me!

[Wesley888]

Nah, only the one that has the bouncing problem would do that. Otherwise it should land picture perfect and not a hint of trying to get back up. Interesting thing is that majority of them never have this problem. Those who have this problem never figure out exactly what caused it.

[hareedy]

some people are very demanding
a few years ago this technology was out of hand for the average man
now its sold every where with a friction of the cost of what its used to be
my advice for you
is to enjoy it the way it is cause there is a big chance you will mess up the settings sometimes and you are gonna end up crashing
i only use rth function when i am flying fpv and i get lost cause i am too high or too far
and i use it only to make it get near then i take over and land it my self

[z_man_95]

How does light affect pressure?