On a regular basis we see builders posting on the forum with a perceived problem on a new craft perhaps on the 1st flight.
First I would say if you are new to Ardupilot use The Methodic Configurator
But, let’s say you made a 1st flight anyway and have been asked to post a link to a .bin log file so we can see what’s going on.
I will use one of my 4" quads as an example of what we often see and what can be done to advance the tuning process.
Some people, usually due to not knowing about the available documentation, launch their craft on default parameters.
What are the first 2 things we want to look at in a log file? Levels of vibration and RC Outputs. This 4" has a very rigid frame and a well isolated FC so nothing to see for vibes.
RC outputs on default parameters:
This is what output oscillation looks like and you cannot advance with tuning until it is corrected.
Well, what about the Initial Tune Parameter Tool in MP? Great idea, let’s looks at that:
Hmm, doesn’t look good at all. Why not? Because for this craft, and many like it, the rate PID’s and the Vertical Acceleration Controller gains are too high.
The Hover thrust on this craft is ~0.125 so let’s adjust these:
Start by cutting the Rate defaults in half. These have been lowered further after testing.
ATC_RAT_PIT_D,0.0015 (Same for Roll)
ATC_RAT_PIT_I,0.05 (Same for Roll)
ATC_RAT_PIT_P,0.05 (Same for Roll)
Set these as per the wiki based on the hover thrust value.
PSC_ACCZ_I,0.25
PSC_ACCZ_P,0.125
Now what do we see?
What we want to see. Now the tuning process can really begin!
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