Alt hold PID - Tried everything I can think of


Im relatively new to APM. I have the APM2.5 with latest Arducopter firmware loaded. I've tuned out my Stabilise flight and its sweet, but I cant seem to tune in AltHold. As I understand it, it doesn't help going on the loiter or anything else, unless this is tuned in.

I've tried everything I can think of to tune it, but cant seem to get it right. The worse of all is, that I cant see a pattern emerging. Doesn't matter what I change the settings to, one time it will suddenly climb, other time it will drop like a rock. I've gotten it to a place where i drops and I can see it trying to climb in short burst, but it cant seem to get there. I've then from that tried to up/down the P rates for Alt, then it changes completely again (started with default throttle and under Alt all 0, just adjusting P).

I've also tried changing the ThrottleP etc, but cant seem to find the balance between Throttle and Alt.

I've read everywhere where I could find something about this, even just tried stabbing in the dark, hoping I would get lucky, but nothing.

If I go back to defaults, the copter just drops like a rock. This is now my 4th weekend trying to get it tuned on my own, but Im starting to give up :) I need help please. Any indication to where I should look or change to would be appreciated.

My Setup:

Custom H Quad

Distance between motors: about 60cm (Diagonal)

NTM 2826 1000kv motors, giving 210w

10x4.5 props

3S 3300, 25C battery


The quad weights about 1.3kg.

Again in stable flight is awesome, but not althold.

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  • Hi Paul,

    I am in the same situation as you! I don't succed for a stable alt hold of my Storm Drone ( ) with the APM 2 and a MB 1200 sonar sensor.Up to now the PID tuning did not bring anything at lower height (1 m ....2 m). The best is some seconds with correct alt hold but afterwards it climbs (sometimes it goes down nearly to ground before). Interesting is, that the altitude is correct (with running motors in hover range) on a testbench for attitude PID tuning (see attached photo). Did you resolve the problem in the meantime and give some tipps? Thanks3692542721?profile=original - The Largest RC Helicopter Online Store - The Largest RC Helicopter Online Store online at the Lowest Price. HeliPal is the largest rc helicopter online store. HeliPal is famous…
  • Do you have telemetry on the quad?  Can you see whether the APM "sees" the correct altitude and that it doesn't fluctuate wildly?  There is no sense in trying to tune altitude hold if the APM works with bad altitude data.  It will stabilize fine, as this uses gyros and accells which will not be influenced by airflow.

    Make sure that if there is any chance that the APM "feels" airflow from the rotors, that your APM's barometric sensor is covered like here :

    Take note, my observations are general ones, I have never tuned nor had a quad, so don't know the intricacies of them.

    Whereabouts in ZA are you?

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