Hello to all … I maidened my heavy octo x8 as written above … It`s my first pixhawk and it flew on defaults … had to increase P on roll and pitch a little first, now I have Yaw on ch6 tuning … Just wanted to share my first logs here and ask friendly for comments of people knowing … Especially if there is any issue with vibes that should be taken care of … Next question is : When do I have to turn off throttle hover learning … I have no precise autority on throttle anyways at the moment … Yaw is better but still away fom perfect … I’d really appreciate any comment leading me to further steps … especially for autotune …
Logs and short video may be viewed here :
Many thx in advance.
D130 v2 octo x8
kde 5215 with triple blades adapters and DJI 17" carbon props
Herkules III okto xl ESC board runnnig 400 Hz
PH 2 Missionplanner latest and copter 3.5rc5
Tattu 6s 16000
5.3 kg dummy weight
I haven’t looked at the log in detail but it looks generally looks OK. Nice transmitter you have there.
The roll is overshooting a bit but it’s hard for me to immediately say if the gains are too high or too low. By the way when adjusting the roll, pitch or yaw gains manually, I’d recommend keeping the ratio of P to I or D the same. I.e. if increasing the gains, increase them all by a similar percentage.
If possible it’s good to keep the center of gravity in the middle of the vehicle between the motors. So you should find you get better control if the bottom is mounted horizontally instead of dangling down. A bottle which is symmetrical (i.e. cube shaped instead of long and skinny) is also better if possible. It can work as you have it of course, just saying that it will be easier on the controllers and you’ll get a better final result.
As a side note, with new vehicles we recommend using the official firmware instead of the beta firmware. This allows the developers to concentrate on issues that we know are related to the beta firmware.
Thanks for Your suggestions … will do so and report … The TX is a JETI DC16 …
The dummy weight bottle shall simulate a gimbal of same weight and size and flex (mounted with gimbal damping unit) … Would You suggest to tune PID with a more fixed weight and later on flying with a “moving” payload ?
Best from Berlin,
Autotune on ROLL worked well without dummy weight … copied values to to pitch … fine response, very direct … But oscillations on ground before take off when powering up motors … Shall I now turn down PIDs down by X % for that ?
And what could be a reason for AUTOTUNE NOT WORKING on YAW … I put the rig up both in AltHold and PosHold, when invoking AT nothing seems to happen … !!!
I attach my log (that seems to be huge).
And other questions please : Do I have to switch off hover throttle learn now … I could not find any satisfying explanation on this … And how shall I tune throttle responsiveness in different modes ? In stabilize it requires a fine hand to find the hover, climbing goes like a rocket ! In alt_hold and pos_hold it’s not responsive at all … How is the best strategy here … ? Again I’d really appreciate any suggestion to that wonderful FC (so far) … I really didn’t expect it flying so good from scratch !!! Please take that as a compliment …
Best from Berlin,
I had a successful yaw autotune ;_) Except ground oscillations shortly before takeoff (have to get it up quickly) it’s flyable now … And it feels (and looks) like it is still overshooting slightly ??!
Would You kindly have a look at my big birs logs please … ?
I would again really appreciate any help.
But I’m very satisfied so far …
Getting it to this point was pretty stressless …
A short .mov of the logged flight is also in the folder …
Best from Berlin, Christoph
“Except ground oscillations shortly before takeoff…”
specially with X8 Copter, this is normal…feedback air stream at ground when starting
is quite strong…stronger than with flat copter…
greetings from Berlin…