Autotune guidance

ArduCopter Copter 4.0
1

I have a few questions concerning autotune procedures.

I have watched several tuning videos, I have read all the tuning sections of the wiki and numerous internet searches.

Hardware: Holybro Pixhawk 4 system, ordered straight from holybro, control is via Jumper T-16 running Yaapu telemetry, Tarot 680Pro Hexacopter, 1355 props, Oneshot125 35amp escs running Blheli, Multistar elite 4006/740kv motors, dual 8000mah 4s Multistar, 12c turnigy batteries

Here goes

I can take off in stab, switch to Althold, then invoke Autotune. The craft twitches per the wiki and videos. When the radio notifies me that autotune is complete, I leave the craft in auto tune, land, and try to disarm, while still in auto tune. I attempt to disarm the craft using stick disarm, yaw left, throttle low, and it wont disarm. If I switch to stabilize, I can then disarm. I attempted to disarm via Mission Planner and received a warning.

Switching to stabilize disarms, but I lose the pids. What am I doing wrong?

Reading the wiki and watching the videos, nowhere does it say what mode to land in.

2

After autotune completes you must turn off auto-tune then turn it back on, basically flip the switch off and then back on again. And then land and disarm and it will save the pids

2 Likes
3

Okay. So take off in stabilized, switch to altitude hold, invoke autotune, when autotune completes, go back to altitude hold then back to autotune, and land in autotune?

4

I just read through the Autotune instructions (because I am about to autotune one for my first time also) and I’ve got to say, this part of the instructions is not very clear. I am glad @Brian_Bourdeau asked, because I would not have known either. I had to read through it a few times before what you posted became clear in the autotune instructions. In fact, I will need to read through it at least once more before autotuning.

5

I actually use POSHOLD. Not althold.

6

This was actually spelled out much clearer in the older documentation.

7

@Leonardthall could you chime in?

8

Thanks @smartdave,

We will have to make this clearer in the documentation again.

If you use Alt_Hold then the aircraft will drift with the air. If you are doing Autotune in light air this is the ideal conditions. In any breeze you should understand how to point the tuning axis 90 degrees to the airflow so any air speed over the aircraft does not disturb the tune.

If switching to Autotune from Loiter (or Pos Hold) then I have made the aircraft gently flight the wind so it does not move by more than about 10m from the place you initiated Autotune. It also will yaw the aircraft to minimise the impact of the moving air flow over the aircraft. The down side of this is the aircraft will make more uncommanded attitude and heading changes that may confuse the pilot.

1 Like
9

So there is a problem here with your ability to disarm in Alt Hold.

Can you provide a log so I can see what is causing this problem?

10

Where I have a issue is with the procedure I think. Let me explain now that i’m on my computer.
Yesterday, I spent a good hour or so attempting to autotune my tarot hexacopter multiple times. I had my laptop, telemetry radio, Jumper t-16 with Yaapu, and a printout of the autotune procedure from the Wiki. The Jumper t-16 has a 6 position push button switch for flight modes. Set up for me as follows, Stabilized, Pos 1, AltHold Pos 2, Loiter Pos 3, Autotune Pos 4, Pos 5 and 6 are RTL.

I took off in stabilized mode, gained altitude to about 60 feet, put the craft into altitude hold, made sure it was stable, then invoked autotune. Roll and Pitch autotune began. I was notified via Mission planner and yaapu telemetry that the autotune completed successfully. The craft was still in Autotune and happily hovering at this point.

I referred to the wiki pages I printed out before continuing,

" 6. When the tune completes the copter will change back to the original PID gains.
7. Put the ch7/ch8 switch into the LOW position then back to the HIGH position to test the tuned PID gains.
8. Put the ch7/ch8 switch into the LOW position to fly using the original PID gains.
9. If you are happy with the autotuned PID gains, leave the ch7/ch8 switch in the HIGH position, land and disarm to save the PIDs permanently."

I was a bit perplexed at step 7.

Since I don’t have high, or low, settings (I understand that high and low are electronics/software jargon), does this mean that I should switch flight modes? i.e. When autotune completes, switch to previous hold mode(Low), then back to autotune (High) to test the new PIDS?

Jumping to step 9, if the PIDs are satisfactory, remain in Autotune (High), Land in Autotune (High), disarm to save new PIDs permanently. Is this correct?

Not fully understanding the procedure, I attempted to land the craft, it was still in Autotune (High) state. I brought the craft in to land. I never changed from High to Low and back to High. I was able to bring the craft to the ground, but could not get it to disarm while the Autotune was still active from the Autotune session, yaapu telemetry mavlink messages kept saying pilot intervention whenever i tried to disarm. I couldn’t disarm from the radio, or from mission planner. I was scratching my head at this point . I decided, since nothing i was doing was working, I would I changed flight mode to Stabilized, and see if I could disarm the craft. That worked! I checked Mission planner, still the same default PIDs.

I would assume, since I did not alter the state of the autotune, i.e. High to Low back to High before landing, the Autotune software loop assumed it was still running which is why i could not disarm?

By the way, I am a retired USAF aircrew. We had checklists for everything.

11

You should really have autotune on its own switch vs a flight mode. That way you hover, put yourself in poshold, then flip the switch. I don’t think you can do it the way you are trying. At least I have never tried it, and based on your results it doesn’t work.

I use a 3 position switch for Stabilize, Alt Hold and POSHold. Then I have separate switches for RTL and Autotune.

You might want to try it the way I have described above

12

The jumper radio has a 6 pos switch vs having to mix switches for all 6 modes available. It’s really a slick setup.

13

No, kind of.

For example switch A has three positions. Stabalize, alt hold and poshold

Switch B has 2 or three positions. Doesn’t matter.
Switch B high is auto-tune and Low is nothing

Before taking off make sure switch B is low and A is what ever mode you want to take off in

Take off and move switch A to POSHold where you want to perform the auto-tune.

Once in position flip switch B to high and invoke auto-tune

Once completed flip B off wait 1 second then flip high

Without touching switch A…

Land and disarm and your PIDs will be saved

After landing and disarming and the pids saved, flip switch B back to off/low and move switch A to what ever mode you want to take off in

Using this procedure you will never have a failed Saving of the pids

14

This is where the log is needed.

15

Hey all.\Been following this conversation as I have a few machines that now need to be re-tuned since I have overhauled and upgraded them…Covid19 has given me lots of time to work on the machines. But soon I want to get them into the air and tune them and had a couple question.s
The documentation states basically to have the machine twitch direction to be 90 Degrees to the wind. Can someone tell me why this is…just curious.
Also during auto tune is it normal for the machine to turn 90 degrees on its own…say doing a roll tune.
I got one machine into the air recently and saw my quad do a sudden 90 degree turn and I stopped what it was doing and landed in fear there was an issue. But a friend told me this isn’t unusual…so wondering why this is the case. Why turn.

Any thoughts would be appreciated.I am a computer operations person and odd not understood behavior doesn’t sit well…unless its supposed to do that and I am just not aware.

Cheers

1 Like
16

What flight mode did you start the auto tune in? Pos Hld, AltHld, Loiter?

17

https://1drv.ms/u/s!AuSRRT1z_xPZg_oborjwW2646kvy2g?e=DN5TVq

The two log files were too big to post here. The above link should get you the files.

18

I started in PosHold.

19

I took a look at your logs. You mot_bat_volts min and max not set which are needed.

I am curious, how long are you holding the rudder to the bottom left? Are you waiting on the blades to spin down first, after the landing (while in pos/alt hold) and then try and disarm?

I find that when I first land the props are still spinning quickly, then a couple seconds later they spin all they way down to Idle, its at this point that you can hold the rudder/throttle down left until the FC beeps

20

i tried again this morning. https://1drv.ms/u/s!AuSRRT1z_xPZg_odqHWQ0LrjhnG30w?e=oDIum6