So I am using a pixhawk on a quad and it works great if I just let it hover, POS hold is rock solid and so is alt hold. But in AltHold or POS HOLD as soon as I give it some forward momentum and then back or just sharp turns it instantly goes 100% throttle until I switch it to Stab and I have to let it fall for a bit until its back at the level it started at at.
Now I know it's vibrations because I review my logs and the Z, x y, accel is great until it it puts out more throttle then it goes crazy and thats when alt hold misbehaves. I tried EKF and issue still happens, I tried really thin "airy" foam but compressed with the same foam on top (made a pixhawk sandwhich), my latest was moongel and I did 2 peices at each end and used its standard pre cut size. I was thinking of doing 2 layers next...
So I am trying to find out which motor, prop is the issue but I have gone through a number of props (I just have been flying normally and not using RTL or alt hold (RTL uses ALT hold so if it goes into RTL I lose my quad in the sky forever)
I switched out a motor since it sounded funny on the bench although I felt minimal vibrations when testing with out props. It just has a "hum" vibration, hard to explain. (this is 4 all 4 motors)
I balanced the props and tested them on the quad and they all produced similar vibes and nothing major
I bought new arms in case some were twisted or something and still same issue.
Tightened all screws
I put it in Poshold and just watched the props for a couple minutes in hover and they looked fine
Frame: Aphid x450 (Uses f450 arms)
Sunnysky xx2212 980kv, 3S, 10x4.5sf plastic.
Replies
So an update,
Purchased new sunnysky motors with t prop adapter, new frame, and new carbon props, seems to fly really well now, hammering the sticks trying to cause massive vibrations and its still good. I think it was motors that caused the issue.
I am having an issue and I beleive it may be becase of of the moongel, I am losing yaw lock, I have not done compassmot yet but thats the plan later today. Just wanted to ask if anyone had similar issues with moongel?
hi, as you say the root of it all is vibration in the motors - so careful balancing will help a lot.
but for the vibration thats left (theres always some), ive found that stiffer foams work much better. if you can, get your APM on a board with as much weight as possible (ESCs? battery? radio?) and isolate that as a single block. in any case i have had much success with neoprene - both a sheet i bought in a local rc shop as "radio mounting foam" and a chopped up mouse mat. recently i am trying 1/4" sorbothane which is also working very very well.
one more thing .. i have a TBS discovery flying with the same motors and found that there is more z axis vibration in the centre of the plates between the arms. mounting at the edge of the plates seems better.
Thank you,
I bought 4 new SS x2212, new frame, new carbon props, I was very rough with the first quadcopter so maybe the motors got a little to much abuse.