Hello. I want to make a plane exclusively for automatic flights. fpv is not supposed to be installed on it, and although I can connect the remote and change pids through scripts, I would like to understand how I can do this only with the help of logs. I started to learn how to tune PID without autotune and came to a dead end. It is clear to me how to set up FF and I based on the documentation and with detailed explanations on the graphs. However, after setting FF and I, it is supposed to set the parameters P and D to 0, and then adjust by adding a little. After adjusting FF and I, I want to set P and D equal to 0.1, and then, based on the flight log, find out what values are actually needed. For setting FF, it is supposed to focus on .345PIDR.ActAETR.SS and AETR.Ail*0.01. what parameters should I display for P and D in order to understand the overestimated / underestimated value? I will be grateful for any help.
I’m not sure if this will help but autotune can be activated in Auto mode now. Rather than re-invent the wheel why not take advantage of that feature? Prepare and fly an auto mission, then use the RC with stick mixing turned on to give autotune it’s required inputs.
https://ardupilot.org/plane/docs/automatic-tuning-with-autotune.html#setting-up-for-autotune
yes, you can do it, but still I would like to understand how to do it manually, so that after test flights, open the log and understand what needs to be changed (if required), and if you understand this, then you can configure everything manually. this is probably the best approach to tune the aircraft.
Have you looked in the wiki about log analysis?
https://ardupilot.org/plane/docs/common-logs.html#topics-related-to-logging-and-analysis
Tuning a PID controller is very iterative. To tune a plane’s PIDs based only on log data would be possible but it would take so long I’m not sure there would be great value in it.
You can apply the principles of Manual tuning to log analysis. That is often done for the fine tuning when oscillations or hunting may not be as clear to see from the ground. But at that point you are taking a plane that is more or less flying well and making it better.
If you are using Mission Planner there are the MavGraphs already built in and you can automatically plot the ATT.Pitch, ATT.DesPitch, ATT.Roll, and ATT.DesRoll. This will show you what the FC is asking for, and what the plane is actually doing. This is probably one of the main logs I use when evaluating a tune. In MavExplorer it’s the Attitude Control graph.