Same pitch and roll values from Autotune

ArduCopter Copter 4.5
1

I’ve noticed a strange autotune result in a couple of my student’s flight logs. Autotune produced exactly the same pitch and roll values. What’s really strange is the same thing happened on two student’s drones.

Matek H743-wlite. bdshot. X500V2 airframe. 4S 5200mah battery mounted longitudinally. AC 4.5.3.

These drones are symmetrical enough that the tuning results aren’t bad, and both drones are flying without issue. But they are also different enough that I just don’t see how autotune could give exactly the same values for pitch and roll. I’m not worried about the tune itself. I’m sharing this mostly because I want to know if there’s something odd going on with autotune or this setup.

I’ve attached the log from one of the autotune flights.

2024-06-21 11:35:00.163 ATC_RAT_RLL_P 0.135000 -> 0.117937
2024-06-21 11:35:00.163 ATC_RAT_RLL_I 0.135000 -> 0.117937
2024-06-21 11:35:00.163 ATC_RAT_RLL_D 0.003600 -> 0.003681
2024-06-21 11:35:00.163 ATC_ANG_RLL_P 4.500000 -> 23.456852
2024-06-21 11:35:00.164 ATC_ACCEL_R_MAX 116700.000000 -> 182888.265625
2024-06-21 11:35:00.164 ATC_RAT_PIT_P 0.135000 -> 0.117937
2024-06-21 11:35:00.165 ATC_RAT_PIT_I 0.135000 -> 0.117937
2024-06-21 11:35:00.165 ATC_RAT_PIT_D 0.003600 -> 0.003681
2024-06-21 11:35:00.165 ATC_ANG_PIT_P 4.500000 -> 23.456852
2024-06-21 11:35:00.166 ATC_ACCEL_P_MAX 116700.000000 -> 194876.187500
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If your starting position for both is the same then I would say its possible. The PID step changes in autotune are a percentage of current PIDs as is the backoff. Those X500v2’s are basically square so will have similar gains in roll and pitch anyway. So I would say yes - certainly possible. Notice that the accels are not the same - that is actually a measured value which you would not expect to match exactly.

1 Like
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Thanks @andyp1per. It’s funny we’ve tuned over 60 of these in the last couple years and I’ve never seen the PID values line up like this. And now we have two. But what you say makes sense. They’re flying well so that’s the main thing.