I’d appreciate it if someone could explain to me what ATC_ANG_RLL_P (Stabilize Roll - Error to rate) is.
The same for PIT and YAW.
More importantly, what increasing and decreasing it does to PID tuning. How it affects it.
This parameter is in MP under Extended Tuning but I cannot find any explanation.
My way of thinking is:
- ATC_ANG P parameters are overall airframe tuning - it’s easy to change these by relatively large percentages and see handling differences without being too unstable or dangerous
- ATC_RAT P I D params are related more directly to motor control (increase/decrease in RPM) - small differences can have significant effects on handling, battery consumption and motor temperature, these are dictated by your motor/prop/ESC/weight combination
These are my own very simplistic views, a controls expert like Leonard Hall may have some corrections for me and would be able to go into great detail. There’s numerous videos on https://www.youtube.com/channel/UCtqkaA8BWDpISGNAfivUSHw/videos
Thank you Shawn,
I know the effects of ATC_RAT P I D. I have a very heavy copter which hoovers at close to full throttle, in which ATC_RAT had to be increased to 0.05 to reduce sensitivity to RPM.
What puzzles me is the ATC_ANG parameter. I’m testing my large copter on a stand and hate to wrack it on its first free flight.
Doubling the default ATC_ANG_P seems improve handling, but in the air it may be a different story. Hence my question.
Another thing is the FILT setting. Default is 20, but when reduced to 10 and below appears to smooth things out. I’m a bit worried to fly with FILT = 5 because don’t know the potential side effects.
I get only one shot at it. Once the copter is wrecked, it takes over half a year to rebuild it.
You can determine practically nothing with the craft on a stand with regards to the PID loop parameters.
The stand allows the craft to rotate about Pitch and Roll axis that go thru the center of gravity.
My initial flights with default settings ended after 4 seconds resulting with total destruction. Only after I got it on the stand I was able to find PIDs that allowed my craft to fly stable so I could fine tune it. That was with my previous copter that was half the weight of the new one. The default parameters are not suitable for heavy copters and for gas powered copters.
So I have no choice but to tune it initially on a stand. Cant afford to lose my new copter.
We hold a copter overhead while the pilot operates pitch/roll/yaw in Stabilise mode to verify responses are as-expected. Not everyone would agree with doing this. Sometimes you could weight or strap and aircraft down for the same test - depends on aircraft size.
Use as little throttle as possible to achieve test results.
We dont run this test very long, just check if movement matches stick input, then move on.
We havent had any issue with the PIDs and getting airborne when following the tuning guide and using the spreadsheet (or Alt A in MissionPlanner).
We have had to make minor adjustments after getting airborne and checking logs before going to autotune.
https://ardupilot.org/copter/docs/tuning-process-instructions.html
If you like, start a thread about your aircraft and tuning, supply a .bin log and a good description of the aircraft.