No Raspberry Pis were hurt in the making of this film…

but once more the blades and the gravel had a major fight, which again, the blades lost!

I think there’s more work to be done here! from Andy Baker on Vimeo.

On the plus side, the blades didn’t slice the LiPo battery power cable, so no risk of explosion – you can see me in protective glasses and gloves this time just in case.

That then means I have diagnostics to interpret, but even without those, just the video itself suggests the pitch PID has too high a gain, meaning it overshoots it’s correction leading to ever increasing front / back rocking.  My code won’t cope with > 90 degree tilt so when the rocking goes over 90 degrees, the drone flips onto it’s head and accelerates hard towards the gravel.

Two obvious solutions spring to mind:

  • reduce the pitch, roll and yaw PIDs’ P gains and / or add a negative D gain to each
  • add support for > 90 swings – this is harder and unnecessary at this level of flight control if fixing the gains works.

Still not sure about the yaw though – far higher than expected still – I think I need to use the yaw angle PID’s I output to infuence the motors much as I do already with the vertical speed PID. But I’ll leave that for another day.


5 thoughts on “No Raspberry Pis were hurt in the making of this film…

  1. Pingback: Super duper WiFi dongles | PiStuffing

  2. Fascinating reading your efforts to get this working. Although this time there was something fairly comedic about the lift off and crash – a bit like Soviet space programme experiments in the 50s. Good luck on getting it to work – I think you’ll get it right!

    • Hi Mike,

      It is ironically amusing isn’t it! And although the net result was the same as before (a terminal crash), I now have a very good idea of the problem, both from a video I can replay, and the diagnostics I got.

      Third time lucky?!


  3. Hello Hove,
    I’m following interested your development, since I’ll be on the same situation shortly.
    (I’m waiting for the first hw delivery).
    Just a comment on yuor approach. why don’t you devide the problem in subsystems. For example why don’t you lock the qpi with a frame with only one degree of freedom per time instead of wires?

    • Hi Oscar,

      I’ve done some flights constrained so I could check whether the PIDs were close to being right. However, they weren’t as refined as stringing up the quad with one degree of freedom – though having now trashed £100 of blades in my 2 test flights, I think I will go that direction next before I try another flight!

      The wires you mention are just bits of string just to prevent it from leaving a 2m radius dome: a safety net to protect me and my neighbours!



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