Need Help tuning large frame hex.

ArduCopter
1

So here is the rundown. Currently in the process of tuning a large/heavy hex. I have gone through the steps on mission planner for setup and first flight ect. I’m at the point of notch filtering & PID Tuning. In Altitude Hold the drone is very stable and smooth (no oscillations to speak of). Now in Loiter I’m getting a bit of a pendulum effect. Which I am to believe that it is caused by low PID’s (slow adjustments) I have uploaded the flight logs for the ALTHD flight also the LOITER flight to see what can be adjusted to help prevent/ mitigate this this slow response. I have had great success in the past with smaller quads that are more agile. But this big hex is stretching my technical knowledge a bit. For clarification here is a breakdown of the full build.

HEX 1600mm motor center to center
T-Motor U10II 100KV
Alpha 60v 6-12s ESCs
T-Motor 30.2x9.9 folding carbon props
Here3 gps (dual)
Herelink Blue & Blue Airunit
Cube Orange+ on ADSB Carrier
Mauch PC4/V3 w/PL-Sensor
17000mah Max Amps 10s 15c 629wh battery
full carbon fiber construction frame (very ridged)
min_TOW 13.8kg
max_TOW 19kg

ATL HOLD FLIGHT

(.bin file)

2023-10-03 07-58-33.bin

(video)

20231003_075908.mp4

LOITER FLIGHT

(.bin file)

2023-10-03 08-07-59.bin

(video)

20231003_080818.mp4

DRONE IMAGES

20230929_083247.jpg

Any input or review of this is greatly appreciated. Don’t really want to test durability through crashing it. The next flight (weather permitting) will be with (FFT) on and ALT HOLD to verify if I’m getting and vibrations that need to be tuned out via “notch filter”
I know this is a lot of info dump, but I would rather be accurate than vague. Thanks again for the help.

2

For what reason did you lower the Rate Pitch/Roll P&I values?

You don’t need to enable FFT but you do need to set these:
INS_ACCEL_FILTER,10
INS_LOG_BAT_MASK,1
INS_LOG_BAT_OPT,4

I’ll assume those Motor Ranges are set because they are the Alpha ESC’s.

3

I have not adjusted the PID settings at all yet. And yes the motor ranges are determined by the firmware(tune) of the alphas and matched as so.

4

Somebody did because these are not default and they are likely going the wrong way from default for a large craft:
ATC_RAT_PIT_I,0.1
ATC_RAT_PIT_P,0.1
ATC_RAT_RLL_I,0.1
ATC_RAT_RLL_P,0.1

5

Yes I’m seeing that default is .135 I have not gotten to adjusting them yet. but i believe i will move those back up to default. Just trying to get ready for an Autotune flight.

6

OK so you did adjust them. There are reasons for doing so having to do with output oscillation and general instability so we need to know why you made the changes.

7

If it was changed it would have to be by the auto adjustment in the initial tune parameters or by accident. None the less is it suggested to adjust them back to what is listed as default? And then re-fly at ALTHD to verify adjustment improvement?

8

Initial Tune doesn’t change these so it must be the later. Yes, set them back to default.

1 Like
9

Thanks. Will do and re-fly in the morning fingers crossed for a more stable-ish flight. I would like to get it as close as possible before doing the Autotune. I appreciate the input and time. Also will reload .bin of flight with the new logging enabled.

1 Like
10

So all has been worked out. Drone is very stable in all flights, and all weights. VTOL QUICK TUNE is absolutely the way to go. Very safe and straight forward. no twitching and jerking like standard Autotune. I have built a lot of drones over the years and have never really like the standard autotune option. But now with this as an option I am happy to say that “this is the way”. Thank you to everyone that helped with this endeavor.