Copter ascends in loiter:Desired Altitude not following loiter throttle rules

ArduCopter Copter 4.6
1

Hello,

I’m trying to autotune/quiktune a Gofilm20 small copter, equipped with Micoair H743 V2 AIO controller and controlled by Arducopter 4.6.3.

In Stabilize it flies more or less fine (needs tuning but is controllable). However, when switched to Loiter, it ascends very quickly irrespectively of the throttle stick position. In the logs, the DAlt forms tall peaks, and is very far from staying level:

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Log

I have calibrated the radio input. Might this be related to the airflow close to the baro? (rather not, as the altitude reading seems to be reasonable)

The hover throttle CTUN TrH stays around 0.34, and the RC3 throttle channel around 1150 for hovering. Might it happen that because this copter weight is so small, these values are somehow not correlated? And Arducopter thinks that this throttle value corresponds to ascending, even if it is well below the middle of the range?

1 Like
2

RC3 at 1500 means hover, you switched to Loiter with 1110 throttle, which means quick descent… make sure when you switch to althold or loiter the throttle is centered.

In althold/loiter the throttle channel is controlling desired climb rate, with center is zero climbrate…

1 Like
3

OK thanks now I understand that the loiter hover is always the middle thottle. Maybe there could be a parameter for loiter hover equal the learnt copter hover value?

But still I don’t understand why the copter was ascending (fast!) and not descending, it the throttle was always below 1500?

4

You’ve missed some tuning steps:

PSC_ACCZ_P, 0.34
PSC_ACCZ_I, 0.68

You should also set up the initial params in mission planner. A lot of params still on defaults and your rate outputs are showing it.

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Before you burn out your motors you should look at How to methodically tune any ArduCopter | MethodicConfigurator

5

No. That’s not in line with the design architecture of assisted flight modes.

6

Thank you very much for pointing at the exact values to look at. I’ve tried to use the methodic configurator, but got lost in the settings and many screens with parameter updates. Usually I got my copters (from medium to big, and also VTOL planes) to fly in stabilize, and then loiter worked more or less “out of the box” and I could run the autotuning. But maybe Gofilm20 is too small and scales differently. The motors are cold and Micoair H743 AIO has plenty of power, so I hope it’s safe. Thank you!

7

I wouldn’t run autotune on this one yet. It’s got a few things to deal with first before you should try that. Setting a notch filter and getting the PID values in a safe range would be a good idea.

8

The trick is to no go to the next screen without fully completing the current one.
And if you have problems with the current one post them here.

Skipping stuff is what gets copters crashed. Not understanding something is not an excuse to skip stuff. Ask questions, we will answer.

1 Like
9

No. Most of my builds over 3” have hover values around 12-15%, meaning the vehicles are extremely overpowered (for good reason). Yet, I don’t have the issue you are experiencing. Mostly b/c I follow the workflow laid out in Mission Planner, the wiki, and fill in the rest with the forum.