Dual Tailsitter

ArduPlane VTOL Plane
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1

Hi all,
I’m working on a dual tail-sitter using orange cube plus and a mini carrier board. Motors are MN4006 with Air40 ESC’s along with digital servos.

Initially flew with the default params using the disktheory and diskloading. Tried quick-tuning as Qautotune is not working for VTOL. Qautotune is telling that level failing, tune manually. This is the first issue.
As quick tune is peitty stable and Qloiter seems to be good, did transition and tried autotune for fixed wing mode. It just starts and stops after sometime.
While bringing back QRTL mode is entered, till the home radius comes fine, does transition. When again in VTOL by QRTL, the behavior is so scary that I had to switch to Qloiter or Qhover to make it stable.

Meanwhile I was getting lane switch messages also.

It will be so much appreciated if some one looks and helps me resolve the issue.

2

you will need to post a log for someone to help you on this

3

Here is the logs link.

4

In the mean while,
While testing VTOL, I saw EKF3 lane switch message with AHRS DCM active message. At that moment i was landing and bird climbed the altitude and I had to kill the bird which crash landed. I noticed one more thing that the altitude on mission planner was showing 30m and GPS location was showing somewhere else when i saw the map.

Did anyone faced the issue like this?
and anyone having the same issue?

5

I hope any developers can address the issue and resolve it
Its been so much time since i posted the issue and no one is interested to look into.

6

your logs are not accessable

7

you mean
the permission?

8

yes…permission is denied to acccess them

9

the permission is given already

10

looking at the logs, my observations:

  1. you have not properly setup any noise filtering…just enabled a static notch with default settings…you cant get best VTOL tunes without noise filtering…follow the wiki
  2. you setup fixed wing autotune to only tune YAW…which an elevon plane cant do…change the AUTOTUNE_AXES and try it again…your fixed wing tune is poor
  3. your VTOL pitch tune is bad…try setting Q_A_RAT_PTCH_FF = .5 set Q_A_RAT_PTCH_P in half since FF will be driving the PID more now and re-run QUICKTUNE script
  4. If you get VTOL Position 1 overshoots, the Q_TRAN_DECEL param can be lowered
  5. the logs do not show an EKF lane switch, but that indicates that a sensor is in wild disagreement with the EKF estimate for it…ie IMU error due to noise or vibrations, GPS glitches, sensor fails, etc.

your landing crash sounds lik it was probably due to GPS glitch/failure causing a switch from EKF to DCM which had a different altitude/pos estimate since DCM is less sophisticated than EKF on fusing location inputs (INS/GSP/BARO) causing the climb

11

Thank you so much
But when i did transitions, the QRTL was scary, as the bird behaved adversely. Is it possible to check that also?

I will be sharing the log soon…

Thanks in advance

12

Also why it did switch to EKF(why there is still DCM working when EKF is sophisticated)?
Is it possible to know why did GPS glitch? Is it because of less signal for the GPS or the interference?

13

DCM is the fallback if EKF declares itself bad…gottta have some kind of inertial guidance active
cant tell you why the glitch…wiring intermittant,interference, GPS cant see the sky fully (common on tailsitters)…don’t have that log…but probably only confirm the GPS glitch not what caused it
the VTOL control looks okay, not tuned well, but okay on that log with all VTOL modes, including the QRTL portion…a tailsitter is very sensitive to descent rate in VTOL (tailsliding) since control surfaces are working backward against relative wind…no ones come up with a good solution because determining a hurestic for true negative vertical AIRSPEED is difficult to use to selectively reverse control directions and how much

1 Like
14

okay

I will refer wiki and set accordingly.
I request you to support me by looking at the logs and resolving the issues.

Thanks

15

I can look at the log for the glitch that you have not linked yet…don’t know that I can help on that but will look when posted

16

@hwurzburg I am following wiki for every setup.
How can I get best VTOL tune without noise filtering?
and is it possible to say what notch parameters i should work on please?

17

tuning VTOL is not recommended without noise filtering

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sorry, but I dont think you have followed all the wiki tuning sections if you have not setup notch filtering

18

okay,
I will recheck again and update the settings.
Will get back with the new test log with changes.

19

@hwurzburg I did fly again
and did dampening and followed wiki for setup.

In Qhover altitude hold is somewhat okay and controls I feel to be much responsive. As soon as i switch to Qloiter everything is reverse. Bird drifts away wont be at a position, does adverse yaw + pitch and don’t take control input sometimes.

Also I observed that the control surface(servos) were making high frequency correction while hovering as well as while pitching also.

Even though i have done all the VTOL maneuvers, in MAGFIT calculator i see coverage as very less.

I request you to look at the log and correct me

Thanks

20

Is it possible to use rangefinder for height estimation during VTOL without altering it on fixed wing mode?
If yes, how?
because my tailsitter Althold performance is not as good as i expected but i feel the controls are good and stable.
I tried to change the EKF3_SRC_POSZ to rangefinder but, i see prearm: AHRS not using configured AHRS type.

On mission planner sometimes i see random altitude values like -7, 30m where i dont even take VTOL to.

I need someone to help me.

Thanks