Altitude Hold vertical oscillations - high power to weight copter

ArduCopter
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Hi all - If I’m flying a small overpowered copter and getting vertical oscillations in AltHold, is it more likely that MOT_HOVER_LEARN is not learning the extremely small hover value and so I should set it manually per this - https://ardupilot.org/copter/docs/ac_throttlemid.html or should I reduce the PSC_POSZ and PSC_VELZ values per this - https://ardupilot.org/copter/docs/initial-tuning-flight.html#test-althold?

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    dataflash log - AMC_2ndFlight_FilterCheck.bin

    First flight with more attempts at AltHold in the log. It just doesn’t seem like MOT_HOVER_LEARN can learn a value less than 0.2? Though I’ve had it learn values under that on other larger copters that were also a bit overpowered.

    Image

    FirstFlightduringAMC.bin

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The learn limit is 0.125.

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Thanks @amilcarlucas ! I’m working through this copter and hopefully another soon using your AMC. I saw this note and wondered if there was some kind of minimum it could learn.

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That thing is a rocket! What is this build?

Don’t forget to turn down PSC_ACCZ_P and PSC_ACCZ_I.

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Haha, yeah I didn’t realize it hovered so low until I looked at the logs, @Allister Funny thing is that it’s like a random open source - SourceTwo frame that I bought a few years ago because it was cheap and then I have parts bin type components on it, some old Emax 2204 2300kv motors, 6in props, and F405 Matek SE and some analogue FPV gear.

I’ve been trying to learn more about Ardupilot acro type flying, since I enjoy flying Betaflight quads in full acro, etc. Probably an F405 isn’t the best to do this with in Arducopter, but it’s what I had. Then I decided to use this frame/build as an Ardupilot Methodic Configurator test mule to learn about how the AMC works. So far I’ve enjoyed it, just trying to figure out a few things, and then this AltHold oscillation came in along the way. Hoping to get this working and flying well - I have another 5in quad that is mostly built and just waiting for the Arducopter treatment if I ever get around to it!

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@Allister did you happen to mean these params from here? I hadn’t seen anything about PSC_ACCZ_I that I was supposed to adjust.

I thought I had adjusted these both, but I guess one of them didn’t save. Hopefully I’ll get another test flight in this afternoon.

if AltHold starts to oscillate up and down the position and velocity controllers may need to be reduced by 50%. These values are: PSC_POSZ_P and PSC_VELZ_P.

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Read thru here and you will get to it. Initial Tuning Flight

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Oh whoops, I was looking for PSC_POSZ_I instead of ACCZ_I. Can’t believe I missed that. Thanks @dkemxr

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Included in Step 20 of AMC

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An F405 should be enough for a straight forward acro build. And if it’s what you’ve got on hand, it’s hard to beat the price.

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Ahh, thanks @amilcarlucas - I opened up my AMC files and it looks like I was just on step 19 and got distracted with fixing this, not even thinking that I should try the next AMC step. I was so close!

btw, I had some other AMC questions - would you prefer I post on the big AMC megathread on the forum, start a new topic. or just use the Discord #methodic_configurator channel?

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Thanks Allister - I don’t know that I’ll get it flying as well as some of Andy Piper’s builds, but that’s what the goal is. :slight_smile: And that’s true, you definitely can’t beat “free.99” !

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For questions use the megathread on the forum.
For bugs or features use github.com

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