Thank you @Leonardthall for sharing this guide! Lot of useful info in there!
I’ve seen you give some insights also on PSC parameters for Z. Great, thanks!
Can you please explain how to set up the other terms?
Why POS I term is missing?
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As for the setup of the XY POS parameters the only real guidance I can give is if you have set up your aircraft to be very slow in roll and pitch then you may have to halve all the PSC_XY parameters.
To answer you question on the I terms. You only need one I term in each control system to take out constant offsets. This is best handled in the lowest loop.
Perhaps to answer your question directly. We don’t need an I term on the position controller if there is an I term in the velocity controller. The only way there is a constant Position error is if there is a constant Velocity error. So we add the I term to the velocity (the inner most loop)
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Amazing work here Leonard!! This is an area of the wiki really needed a touch up. Excited to see the improvement people see in there birds with all the effort that has been put into this. Let me know if there is anything I can do to help the cause.
-Ed
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Really amazing work, I re-tuned all my copters following the new wiki and I saw substantial improvements.
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Hello All,
This is a great effort and a huge help for beginners like me who generally jump too quickly into AutoTune, without setting-up the required parameters for starting a tune and end up in CRASH
Good news is that I have rebuilt the whole thing and getting it ready for first flight 
I have generated Thrust vs PWM data for four KDE-3520XF-400KV motors, KDEUAS55HVC (55A+HV) ESCs with T-Motor 18x6.1 props on an RCBench Series 1520 thrust stand. Its just one data point on the curve but I hope it will be useful to verify the approximate MOT_THST_EXPO curve.
https://www.dropbox.com/sh/3glldns2s184pnn/AAB4sx0tYDtVABXVcI3icuy8a?dl=0
I would be glad to perform the same on other Motor/ESC/Prop combinations that i have and share the data with community if it carries enough value to justify the effort 
P.S: Can you please guide on how to use this data to get the MOT_THST_EXPO value?
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@Leonardthall on this thread MicroArduCopter, 3" props, Omnibus Nano, Success! I read that also EK2_ABIAS_P_NSE is an important parameter to tune in order to improve stability on small (3 inch) copters. I would like to know what do you think about it.
I can’t provide any thoughts on this without seeing the issue myself.
Sorry, I have not had time to write up an explanation of this yet but there is a pretty big conversation about it here:
There is a bit of drama in that thread but I went to a lot of effort to explain how I choose that value and where there are some tricky things to deal with.
OK thanks the same.
I saw your work on system identification with chirp signal on the PR, it is really awesome.
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Thank you! great and detailed description of the tuning process!
Can you describe the logic behind suggested filter hz values? Any relation to motor speed or build natural frequencies?
Any info on FF parameters use / setting with multi-copters?
The filter frequencies are really about the agility of the drive system and inertia of the aircraft. I have built very agile 30 kg racing multirotors that need filter settings similar to a 10 inch quad for example.
These instructions are focused on an optimal performance tune. These filter settings are much more complex if I am doing a noise limited tune but I have no idea how I could give instructions on a noise limited tune. (where noise levels are the such that the PID’s can not be tuned up to an optimal tune without the noise swamping the motor outputs).
Classic multirotors do not use FF. the FF is for aerodynamic surface controled aircraft like heli, single and coax copters.
Thanks for the great wiki page, started fine tuning our large hexacopter with 30 inch props with it this week. Changing the MOT_THST_EXPO param seemed to have the biggest impact as it was set at default 0.65 to start with. Tried stepping it up to .75 initially and then to 0.8. There was little notable difference between 0.75 and 0.8 but both had major improvements to control ability from the default setting. Makes flying feel a lot safer.
Current rig is running:
30 inch props
T-Motor U8II KV85 motors
T-Motor Alpha 60A HV ESCs
I saw in another post that T-motor ESCs might work well with a low EXPO value, but its running so well on the higher value I’m hesitant to try it.
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That would have been me. On some of the earlier t-motor escs they did internal compensation that messed things up. I have not seen it for a long time now though.
Good to know! Thanks for the update.
Hello Jake,
I am working on a large hexacopter myself with a similar setup (30 Inch Props on 100KV Motor). I have completed the assembly and Pixhawk setup and done all the tuning setup according to the new tuning guide. I will be attempting a first flight soon and wanted to know your experience with first flight and what changes did you made from default parameters specifically the PID gains.
How different are the gains now after tuning and fine tuning. A screenshot of Extended Tuning page from Mission Planner before and after tuning would be a great help, or perhaps you could share the .param file.
Many Thanks
First flight was with default PIDs. After conducting an auto tune PID values were in the middle of the specified range, I can post the specifics at a later date, but not at the moment as the aircraft is being used for a project. Do be cautious with the values after the tune as we attempted a tune with the aircraft that returned very low values, around 0.6. We are not sure what caused this, after a crash and a second tune we got values that made more sense.
With default PID gains and MOT_THST_EXPO set appropriately you should be able to safely fly the aircraft. Best of luck!
I’ve got a question regarding prop size and Octoquad/X8 config;
A few key parameters can have initial settings based on prop size, so how do we treat the X8 with two props (the same size in this case) on one arm?
I think we would still treat this as just one size, for example 1555 props upper and lower = 15 inches in all the above posts and parameters, and we wouldn’t try to sum them (30 inches) or do anything special.
I’m not as sure about an X8 config with different size props (and possibly different motors too) for top and bottom. For example, upper props are 1855 (18 inches) and lower props are 1555 (15 inches) probably with high KV motors for lower props.
Would we :
- Try and average the two, 16.5 inches in the example
- Pick whichever you think will have the most effect (thrust, drag) 18 inches
and use that for the calcs in the new tuning guide.
Although I’m using props of the same size and same KV motors for upper and lower, I read where people think there’s merit in using slightly smaller higher pitch lower props and high KV lower motors - so I wonder about the tuning intricacies of such a config. Still I’m suspecting the difference in prop sizes (and potentially coupled with motor KV) wouldn’t make much difference.
All thoughts welcome
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This is correct.
If you want better than that you need to start measuring the thrust curve.
Yes there are lots of theories out there but most of the data has been produced without considering how multirotors are configured. For example most of the data is based on torque matched upper and lower blades. This is not the way an X8 aircraft will drive the props so it is not relevant for those aircraft.
Thanks a lot for your reply Leonard - I think I understand your answers, it certainly clears up some things for me.
I put together this spreadsheet for calculating some initial values based on the new tuning guide. You will need to judge for yourself if the calculated values suit your craft.
You should probably read and understand the new tuning guide to know what these new values mean.
https://ardupilot.org/copter/docs/tuning-process-instructions.html
WARNING: formulas are derived purely on eye-balling the graphs in @Leonardthall 's guide and recreating them to gain some formulas. The graphs I recreated are on separate tabs and you don’t need to look at them unless you feel like updating them and putting changed formulas back into the main tab.
- Enter your prop size in inches, and the number of LiPo cells.
- Copy/Paste the calculated values into notepad++
- Search, Replace
- Select Search mode “Extended”
- Find what: /t {tabs}
- Replace with: , {commas}
- Save As some_filename.param
Apply the new .param file using Mission Planner or similar - I find this quicker and easier than manually finding all the parameters and trying to set them without making mistakes.
Everyone is free to provide feedback, modifications or otherwise.
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