Inav: Fixed wing: How to Tune minor Oscillations on roll? (could have been done with D-Term)?

[Pairan]

This is surely a SUPPORT question!
Currently the Wing flies good, just some minor oscillations on the roll axis are annoying me.

Currently installed v2.4.1 - but this is surely the same as for 2.5.x

fw_p_roll = 9
fw_i_roll = 1
fw_ff_roll = 85

As the D-term has been removed from the cli as well as from the configurator, I'm a bit stuck on how to fix those oscillations.

How can I improve on that? ... raising FF?

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[digitalentity]

Can you please share:

1. Dump
2. Blackbox log
3. Description of your wing

[Pairan]

I will have to make a log on next flight. Never worked with logs before- anything I should know/need to have checked?

The wing is a Reptile S1100 Harrier with two motors

So far I can provide a DIFF or an outtake from that with the related settings. I you prefer the full dump then let me know. I will provide that later.

The Diff

INAV/MATEKF405SE 2.4.0 Feb 11 2020 / 22:58:10 (bcd4caef9)

GCC-8.2.1 20181213 (release) [gcc-8-branch revision 267074]

mixer

mmix 0 1.000 0.000 0.000 0.000
mmix 1 1.000 0.000 0.000 0.000

servo mix

smix 0 3 0 50 0 -1
smix 1 3 1 50 0 -1
smix 2 4 0 -50 0 -1
smix 3 4 1 50 0 -1
smix 4 5 8 100 0 -1
smix 5 6 9 100 0 -1
smix 6 7 10 100 0 -1

servo

servo 3 1000 2000 1560 -80
servo 4 1000 2000 1450 80

feature

feature -SOFTSERIAL
feature BAT_PROF_AUTOSWITCH
feature MOTOR_STOP
feature GPS
feature LED_STRIP
feature PWM_OUTPUT_ENABLE
feature FW_LAUNCH

aux

aux 0 0 1 1800 2100
aux 1 2 0 1400 1800
aux 2 3 0 1175 1225
aux 3 9 0 1150 1250
aux 4 8 0 1075 1175
aux 5 35 0 1800 2100
aux 6 27 3 1425 1600
aux 7 28 3 1800 2100
aux 8 11 5 1750 2100
aux 9 18 0 1075 1175
aux 10 32 6 1050 1325
aux 11 33 6 1325 1800
aux 12 34 6 1800 2100

master

set acc_hardware = MPU6000
set acczero_x = 108
set acczero_y = -41
set acczero_z = -586
set accgain_y = 4089
set accgain_z = 4034
set mag_hardware = NONE
set baro_hardware = BMP280
set pitot_hardware = NONE
set rssi_channel = 12
set serialrx_provider = CRSF
set motor_pwm_rate = 1000
set motor_pwm_protocol = ONESHOT125
set failsafe_procedure = RTH
set align_board_pitch = 30
set model_preview_type = 8
set small_angle = 180
set imu_acc_ignore_rate = 10
set disarm_kill_switch = OFF
set applied_defaults = 1
set gps_ublox_use_galileo = ON
set nav_rth_climb_first = OFF
set nav_rth_allow_landing = FS_ONLY
set nav_rth_alt_mode = AT_LEAST_LINEAR_DESCENT
set nav_rth_altitude = 10000
set nav_fw_cruise_thr = 1450
set nav_fw_launch_detect_time = 20
set nav_fw_launch_thr = 1600
set nav_fw_launch_timeout = 20000
set nav_fw_launch_climb_angle = 20

profile

profile 1

set fw_p_pitch = 9
set fw_i_pitch = 20
set fw_ff_pitch = 91
set fw_p_roll = 9
set fw_i_roll = 1
set fw_ff_roll = 85
set fw_i_yaw = 14
set fw_ff_yaw = 63
set dterm_setpoint_weight = 0.000
set nav_fw_pos_z_p = 35
set nav_fw_pos_z_d = 15
set rc_expo = 60
set rc_yaw_expo = 40
set manual_rc_expo = 60
set manual_rc_yaw_expo = 40
set manual_pitch_rate = 80

[schnupperm]

I have the same problem (Dart 250G, under 250 g).
Is it save to set pid_type=PID on a fixed wing, to get the D-term back?

[digitalentity]

It's generally safe to change the pid_type to PID, but you'll have to figure out proper P-gain. Generally, oscillations could be caused by any of the PIFF terms.

@Pairan based on your dump you may want to have lower FF and higher I and P for roll. Generally FF is is a direct connection to you stick in ACRO (think "manual mode"), while P and FF offer actual stabilization against plane movement. Try lowering FF considerably and raising P - should help get oscillations under control. What are you roll_rate and pitch_rate parameters set to?

[Pairan]

@digitalentity
I will try that- in the moment I wrote this, I was a bit clueless on how to get hold on it. But digging a bit in the wiki I found to raise P and I a bit.
Lowering FF and raising P will get a shot on next flight- as well as a log if 2GB SD will be sufficent for such a task.

I'm a cruiser making these videos while passing over the landscapes so usually I stick in HOR or CRZ. Reduced Pitch and Roll rate a lot ... but I need to take a look at the settings, when im back on the Harrier. By that time I will report back in.
Thanks for your support ;) Greetings goes out to you in Switzerland!

[digitalentity]

I have an S1100 on the way - fingers crossed that would be my main HD-wing, so I guess I'll have the same issue as you )

[Pairan]

It's more a quality detail than an issue ... but to calm a wing down so that 4K footage can go smooth is a lovely thing to do!
If you need anything/infos around that wing, let me know ... I guess I can tell you a lot. Currently running 50min on a flight

[tiriad]

Try to increase i and decrease p?
the following video explains it in detail https://youtu.be/A45vc4OihgY?t=584

[Pairan]

I will be honest: I didn't like the way the wing got tuned in Pawels video. My wings usually fly pretty smooth. But the tuning is (/ my settings are) far from what Pawel suggests. Nothing to complain on Pawel's work, so don't get me wrong.

The main problem seams, that everybody has his own way to tune!

• The Wiki says: raise P for stability!
• in this Thread DigitalEntity suggests Raising P and lowering FF
• you suggest lowering P and raising I
  ...

I try to stick to what iNav offers/suggests - make the wing fly and perform an autotune, which I have had good results with
Then i start tweaking on it as the final result isn't far from the autotune.

My Problem is, that I look for a solution which is "up-to-date" (P-I-FF) and like what "raising D a bit" would have achieved

[dragnea]

This is surely a SUPPORT question!
Currently the Wing flies good, just some minor oscillations on the roll axis are annoying me.

Currently installed v2.4.1 - but this is surely the same as for 2.5.x

fw_p_roll = 9
fw_i_roll = 1
fw_ff_roll = 85

As the D-term has been removed from the cli as well as from the configurator, I'm a bit stuck on how to fix those oscillations.

How can I improve on that? ... raising FF?

Hey.
Lower p and raise i to benefit of stabilisation in air mode. If you want to cruise, you’re using cruise and/or implicit angle mode, so imho try to lower the angle strength but after you put some i term... also, try to add some Adjustments. It will make your life easier tuning in the air... https://youtu.be/KoJmKmrHE50

[Pairan]

I will give it a try!

The adjustments was something I tried out some time ago. But I found it to be a hassle to configure for a temporary setup. Ended up with the idea, if I would do so, I would copy the model (in the Transmitter) and program the adjustments into the copy! Then, when the adjustments have been made, simply dispose the copy.

Thanks for your reply

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