Aeronavics / Droidworx Developed a wierd oscillation with the XM6 - Help Needed

[Benjamin Rowland]

I've run into a strange problem with our XM6. A few days ago it was flying great. Then I finally put the AV200 gimbal on it. Now it is oscillating and vibrating badly. I pulled the gimbal off and it flew fine. I put the gimbal back on - problems. I tried adding some weight to the gimbal to simulate a camera and it didn't change things - might've been worse.

Right as it reaches the point where there is enough power to almost lift it off the ground, the gimbal starts to swing a bit. Then this is picked up by the rest of the copter and the whole thing just shakes.

Here's what I plan to check for:
prop balance
motor balance
a demon

If anyone has additional suggestions for issues to look for, PLEASE comment.

 

[Benjamin Rowland]

I checked the prop balance and they're darn near perfect, so that isn't it.

 

[Muunk]

You have to change gains when you change weight.

 

[Benjamin Rowland]

You have to change gains when you change weight.

I'll try that when the rain stops. I messed with the gain a bit, but I'll dive into that a bit more. The oscillation is pretty violent though.

 

[Razzil]

When I was using the Hoverfly boards on my CX4 ... changing batterys from 2x2250mah to 1x6000 made it go all over the place. Really didn't like the extra weight. Adjusted my gains and everything was hunky-dory.

 

[Benjamin Rowland]

Looks like it was a gains issue. I haven't fully tested it, but based off of a quick test on my front porch (it's raining here) that seems to have fixed it. I'll report back when the sun comes out. THANKS FOR THE HELP! You guys rock!

 

[DucktileMedia]

Thats weird as my XY8 was going ballistic on the Xoar props but not on the same sized APC props. but when I took the camera off everything was fine, with camera it looked like the arms were literally going to shake off. I never changed gains as I just couldnt see the props making such a huge difference and making the whole arm bounce up and down. Now if the whole heli was jumping around like they do when gains were off i think I would have noticed this and tried that first. Hopefully you have it sorted out.

 

[kloner]

what kinda numbers are your guys hfp gains

 

[nicwilke]

Ben,
My XM6 was showing those exact signs. I have 13's on it, and no weight (ie: no gimbal/camera), superb.... Add some weight, and the more weight I put on it, the harsher the oscillations. It'd hover fine, but under a little more throttle, it would do as you're describing. I use ZeroTech YS-X6, so I can land, add some motion compensation via my phone's GCS, and fire it up to iron it out. I found that my XM6 flies best with APC 12x3.8's, and thats at an AUW of around 5kg (just under at 4900g). I asume you're machine will be heavier with retracts and AV200 instead of Av130 like me, but I'm also thinking that you may be nearing the end of your lifting capability with those 13x6 Xoars. How hot do your speedies get?

 

[Benjamin Rowland]

I gave it a quick test when the rain stopped for a moment. Lowering the gain seems to have fixed it. I'll have more info when I give it a proper test on Friday when we'll finally have decent weather. Nic, I'll be sure to check temps as well. For the cameras we'll be lifting we probably would've been better off with the AV130 on this rig.

 

[nicwilke]

Nic, I'll be sure to check temps as well. For the cameras we'll be lifting we probably would've been better off with the AV130 on this rig.

I think the AV130 is perfect for the XM-6, but sometimes it feels a little too small. I would have loved to lift our Canon Xf100 on occasions, but its too large for the AV130. The gimbal we'll put on this rig next will be interesting. Looking at a Cinestar 8 or a skyjib 8 later this year, so will no doubt rack your brains there mate.

 

[DucktileMedia]

Kloner, I'm around 40 on my xy8. Any higher and she goes nutso.

 

[ChrisViperM]

Is it possible to change the COG with your Hoverfly board....your physical COG definetly will change if you hook up a gimbal and and a cam. I am not very familiar with Hoverfly boards, but on whatever I was flying so far, correct COG was almost always the cure to wobbely or unstable flying.....setting the gains was more of a fine tuning after COG was set as close to perfect as possible.

Chris

 

[Benjamin Rowland]

Is it possible to change the COG with your Hoverfly board....your physical COG definetly will change if you hook up a gimbal and and a cam. I am not very familiar with Hoverfly boards, but on whatever I was flying so far, correct COG was almost always the cure to wobbely or unstable flying.....setting the gains was more of a fine tuning after COG was set as close to perfect as possible.

Chris

Setup of the HFP is pretty basic but it works! I adjusted the gain and it was back to flying great. There's a gain setting for flight and a gain setting for altitude hold, and that's pretty much it. And you can adjust those from the transmitter. There isn't a COG setting. There are a few parameters you can fine tune in the software, like the smoothness of the autoleveling (works great), but setup is pretty simple compared to the competitors. I haven't tried the GPS board yet, but I've got one on my desk waiting for me to put the time into it.

 

[ChrisViperM]

Glad you could sort it out.....also interesting to know that the HF board is "pretty simple" to set up.....following your posts, I know you are a big fan of Hoverfly.....will give it a try.


Chris