Arduplane 4.2.0dev Autotune

Re-doing the autotune with the AR Pro running Arduplane 4.2.0dev on a Matek F405-Wing. I put this short video together for those interested in how it works, pretty quick and easy! I'll edit the rest of the flight in HD and upload it soon. Thanks for watching!
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[@bomberaustychunksbruv4119]

They have nailed the AHI haven't they!, it was dead on the whole flight.

[@bonafidepirate]

Yeah I'm always impressed with that! lol

[@yojazdayo]

wow, video is crystal clear

[@MCsCreations]

Fantastic flying, Keith! 😃 Pretty interesting the autotune process! Thanks for sharing it! Stay safe there with your family! 🖖😊

[@iforce2d]

Excuse me sir.... no sweet landing?!?!?! This is unacceptable!

[@bonafidepirate]

Gotta watch the second half in HD! lol I'll upload it soon, probably later today.

[@MarcFPV]

Nice showcase for the Autotune. The pitch on a glide is very likely restricted by the stall protection. I guess this is on by default. It prevents you from pitching up and also limits the bank angle when the airspeed is too low. so the plane won't stall.

[@bonafidepirate]

STAB_PITCH_DOWN is the only thing that should affect the pitch in FBWA, it's explained here. ardupilot.org/plane/docs/parameters.html#stab-pitch-down It's only lowering the nose 2 degrees at zero throttle. My max pitch angle is at the default 20 degrees, so in theory I should still be able to raise the nose 18 degrees above level while gliding in FBWA. I think I'll play with MIXING_OFFSET to balance the pitch and roll response which may help a bit. Maybe raise the max pitch angle a bit too.

[@MarcFPV]

@@bonafidepirate makes sense. Good to know. So I guess the stall protection then only limits the bank angle? Have to look into the description again.

[@SILVIOFRANCO1]

Very nice the autotune process. What is your preference? Ardupilot or Inav? Good flights

[@AerialWaviator]

You may not have an answer for this ... I'm curious if one should have a target A/S in mind when doing an autotune process? Only asking as noticed you did roll tuning at ~50-55 mph and pitch tuning at 35-42 mph. Maybe it doesn't matter. Naturally the control surfaces will be more responsive at higher speeds for same amount of defection, less so at lower speeds. Not sure how this is accounted for in FC autotune process. ie: should we tune at typical flight speed, or should be varied to get better results of a wider speed range. (question is not specific to Ardupilot, or INAV, just curious) ArdupilotTKOFF_THR_MINSPD param for throttle-off minimum speed. It may explain the running out of up elevator authority on landing, depending how it compares to the stall speed.

[@bonafidepirate]

Ardupilot scales the PIDs according to airspeed to account for the effectiveness of the surfaces changing. It does need to know roughly what the intended cruise speed is, which is set by the "SCALING_SPEED" parameter. I don't think it's super critical to tune at a specific airspeed because of this, but typically I tune at the cruise throttle I'm shooting for. (not that throttle was 35% for both roll and pitch tuning) Normally I don't have an airspeed sensor so that target throttle plays a bigger role, but even without a sensor it uses estimated airspeed to scale the PIDs. The TKOFF_THR_MINSPD parameter only works to suppress throttle until the plane is above the set speed during an auto takeoff, useful for a catapult launch from what I gather reading about the parameter and what it does. It shouldn't be active during landing.

[@AerialWaviator]

​@@bonafidepirate Did notice you set throttle at 35%, a number seen used on previous flights. Guess not to critical as flying reasonable level and good enough for most flying circumstances. :) Thanks for taking time to answer questions and providing context.

[@cgwclimber]

Nice video! Wondered if the autotune automatically saved the changes, and if there were any reasons you altered parts of the PIDs on your own?

[@siogana]

Hi.. Im using 4.3.2 on matek f405 std. When i did autotune....flight mode still on fbwa... N message stopped autotune came out.. Any sugestion?

[@stephencarlson6297]

Just checking for clarity: Is this actually 4.0.1dev, or 4.1.0dev? 4.0.1 is over a year old at this moment.

[@bonafidepirate]

It's 4.2.0dev, or the "latest" branch. I'll fix the titles. ;) Thanks for the heads up!

[@sarahdaviscc]

Love your AR Wing Pro videos. How do you digitise the analogue video so clearly?

[@bonafidepirate]

I think it's a combination of a few things. A decent FPV cam to start, a well matched vtx and receivers, a good capture device to get the video into my PC, and capturing it with relatively high bitrate in OBS so it doesn't get demolished when I edit and re-encode before uploading to KZbin.

[@sarahdaviscc]

@@bonafidepirate what VTX and VRX do you use? Also, what analogue capture card?

[@bonafidepirate]

@@sarahdaviscc 800mW Partom transmitter with a Racewood receiver that's no longer sold, but the RMRC ones use a similar RF module and should work as good. For capture I'm using a GV-USB2 from IO Data

[@sarahdaviscc]

@@bonafidepirate thank you so much!

[@nicfpv9969]

Hello bona, is this the same procedure to tuned a vtol?

[@jhughes2286]

Hello Keith, Are you still flying this Ar Pro with the Li Ion 4s3p or are you using the Turnigy 4s 5200? Also your efficiency is amazing, with a 5.5 mph headwind you were sitting at a steady 110 mah/m.

[@bonafidepirate]

Yeah, still the 4S3P 18650 pack. That's pretty much what I'm averaging is about 110 mAh/mile with this one. It's the stock motor and ESC (Sunnysky 2216 1400kV) with a APC-E 7x6 prop.

[@SamStack]

I've never noticed the messages during auto tune before. Is that a new feature of 4.2?

[@bonafidepirate]

I think it's there in 4.1 and later.

[@mrreddog]

I know Autotune Confirmation has been in older firmware from long ago using pixhawk 1 & 3dr radio to Mission Planner on a laptop, but cant remember if it displayed the pid values. But it would definitely say "Autotune successful" on MP hud screen when completed..

[@flyingrock6381]

Good stuff! What autotune level was that? Default 6? Cheers!

[@bonafidepirate]

Level 7

[@mrreddog]

Your LIM_PITCH_MAX & LIM_PITCH_MIN are at defaults of 2000 & -2500. If you raise these, you should get more pitch authority, I think? I don't have any wing experience, but its helped me on other planes....

[@bonafidepirate]

Yes, 20º up and 25º down. I could try raising them, but I'd think 18º (considering 2º down added by STAB_PITCH_DOWN) would be enough for a flare at landing. It's barely able to hold the nose up level at full stick once the wing slows down. The log shows it's "requesting" more pitch up angle than what's achieved. Asking for more may or may not help... lol In manual mode it will easily pull the nose up until it stalls. I'll play around with it and see if I can figure it out.

[@mrreddog]

​@@bonafidepirate HUH? Try adding 10 more degrees to LIM_PITCH_MAX as a test. Thats all I can think of??, I'm no pro, but it really helped my Stratosurfer. But it could of been due to motor thrust pushing from above??

[@jimmytheriot8978]

Have you tried the fatshark HD system

[@bonafidepirate]

I have not

[@jimmytheriot8978]

Could you do a video on how to set the two switches you need for mode switches

[@rakinye8843]

how to put video in QGC windows

[@bonafidepirate]

That's only done during editing. When I fly I have my video up on one screen, normal QGC on another, and OBS running to blend to two into what you see here for recording. I wish there were an option to do it within QGC, I'd free up an extra screen... lol

[@Tyler-qz9uc]

How are you estimating Wind speed?

[@bonafidepirate]

Ardupilot estimates it based on changes in GPS ground speed vs. direction. It's even more accurate with an airspeed sensor. There's some explanation here, it's in the copter docs, but the principles are the same for planes ardupilot.org/copter/docs/airspeed-estimation.html

[@Tyler-qz9uc]

@bonafidepirate thanks! I appreciate the quick response!