PX4 excessive (maybe) jitter in Baro Alt

Log Analysis -- deprecated Copter Logs -- deprecated
1

Hi,

I have two PX4 systems set up which both show what I think is quite a bit of jitter in the Baro Alt log.

One on a F330 Flamewheel and the other (BaroAlt.jpg log file enclosed) for a Flip quad which is a 380 sized copter with DJI motors and 10" props.

As best I can tell the jitter is somewhat over 1 meter plus and minus.

Both of them have a small piece of foam stuck over the Baro between the FMU and IO boards.

Both have hard tops but are open on the sides with no other enclosure.

Both PX4 copters are a bit bouncy in Alt Hold modes. :open_mouth:

I have an APM in an enclosure with foam on another F450 Flamewheel which has jitter at about the same frequency, but less than 1/4 the amplitude and it holds altitude rock steady.

All my controllers are mounted on Kyosho Zeal Gel and have very low sub 1/10 G vibration in all 3 axes.

My supposition at this point is that propwash back pressure is causing excessive jitter for the barometer and that the best way to ameliorate it is going to be to provide some kind of more effective enclosure.

But this thread is here to elicit feedback from others who may or may not have this problem with unencased flight controllers.

Or to anyone who has a solution for it.

When it is solved, I will publish the relevant data in the Wiki. :bulb:

Best Regards,

Gary

2

The problem is related to proximity of the Prop tips to the multicopters central frame plate.

On my lip the very ends of the 10: props actually are directly over the very corner of the frame plate.

This allows considerable pressure pulses from the prop down wash each time a tip passes over the corner of the frame plate to be produced above the frame plate.

Most copters prop tips pass well clear of the central frame plate corners and do not have this problem.

Smaller props will cure it and an enclosure vented at the top will probably alleviate it.

But if you have bouncy copter syndrome look at prop tip clearance from central frame plate first probably at least an inch is good. :wink: