ALT Hold PID on MW 2.4

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skoubri
Posts: 18
Joined: Sun Mar 03, 2013 1:24 pm

ALT Hold PID on MW 2.4

Post by skoubri »

Hi to all, i am running multiwii 2.4 on a CRIUS AIOP v2, F450 frame, 6S, 380KV motors on 10x4.5 3-blade props

Trying to adjust ALT HOLD from zero, i am having some questions... Most of the guides say to start from D value which adjusts Z ACC sensitivity, then P (for the baro sense) and finally I for voltage drop...

So i started from D but even at the highest level (100) i didn't get the "yo-yo" behavior... It reacts but nothing more... so i put a value around 60... then playing with P there is always a yo-yo movement probably due to the baro error, right? And there i have to go from 5.0 to 8.0 to see some major difference... i left it on 5.0.. and finally, the I parameter, no difference from 0.030 up to 0.120!!... With values p5.0, i0.120 and d60 seems pretty stable with no more than 50cm variations for the most of the time.. because some times it looses more height and corrects after some time too...

With this adjustment, when i am in HORIZON+MAG+ALT mode when i am trying to move it starts to loose significant part of its height making me uncomfortable...and finally correcting by hand. Any suggestions or feedback for proper ALT HOLD?

Many thanks in advance!

michelsneto
Posts: 3
Joined: Sun Mar 15, 2015 10:24 pm

Re: ALT Hold PID on MW 2.4

Post by michelsneto »

Hi Skoubri,
My is a quad frame quanum venture with 2213-935 motor, 2 blades 8x4.5 propeller 3s running the same as yours multiwii 2.4 on a CRIUS AIOP v2.
Almost everything apart from altitude control is working fine.
Like you did, I also tried many many tunings but nothing really worked, normally extreme behavior or too aggressive yo-yo or too slow and lazy, 5 meter amplitude variation.
I was so unmotivated just flying in "manual mode". Altitude hold? almost give up...
I never reached so large tuning values like you did, mine D=4 ; I=0.03, And P=1;
I will try your values next weekend.

FengShuiDrone
Posts: 234
Joined: Wed Dec 24, 2014 1:20 am
Location: ......

Re: ALT Hold PID on MW 2.4

Post by FengShuiDrone »

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Last edited by FengShuiDrone on Fri Aug 07, 2015 4:43 pm, edited 1 time in total.

skoubri
Posts: 18
Joined: Sun Mar 03, 2013 1:24 pm

Re: ALT Hold PID on MW 2.4

Post by skoubri »

Thank you both for your replies... I have been using the 10'' 3 blade for two reasons: first I cannot find larger 3 blade :), second I am TOTALLY stucked at 3 blade config as I can balance them dynamically to almost ZERO vibration and maybe that's why as michelsneto states I can get pretty high numbers at all PID settings, I just keep them low to have some smoother response.
Also after many many hours of research and bench tests these specific motors have the best efficiency with these props at hovering RPM. And I think that with this setup, two batteries 5200mAh (no name, chineese) and full-setup including aluminium gimbal, gopro hero 2, all boards (fpv, osd, etc), and lighting system, to have standard flight time 25-27 minutes in any condition is fair...
I am still searching on this... :)

michelsneto
Posts: 3
Joined: Sun Mar 15, 2015 10:24 pm

Re: ALT Hold PID on MW 2.4

Post by michelsneto »

Feng Shui Drone, your comment about my, possible, undersized propellers seems to really make some sense because other thing that I forgot to mention...
I "feel" that the reaction capacity to fall is much more stronger than rise capacity, in other words, many times I have to go to 100% throttle to revert the falling rate and not crash in ground. My flight weight is about 1.1 Kg draining 15 amps from my 3S in hovering mode with 2200mAH and about 6 minutes flight time. I tried another 3S 4000mAh battery and the flight time remains almost the same indicating that the extra battery weight do not worth to increase flight time.

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