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BigQuad Unstable - Constantly changing values for roll\pitch

Posted: Sun Mar 10, 2019 12:54 am
by Lombazombie

So I have build a bigger drone with the bigquad and am having some issues with it being rather unstable.
  • The vales for the roll and pitch will be constantly changing (usually increasing) when the drone is on the table.
  • When running the python example for the multiranger_push
    • Does not hold position
    • Flies uncontrollably (usually crashing)
  • Motors seem to be overcompensating, causing it to flip.
Once again, thank you so much for all the help! Any ideas why this is happening would be great.


Re: BigQuad Unstable - Constantly changing values for roll\pitch

Posted: Mon Mar 11, 2019 2:04 am
by ricardo.halfeld
A bigger quad is likely to need different PID settings for attitude at least. Its dynamics may be very different to the Crazyflie.

I suggest restricting some of the degrees of freedom until you find the ballpark for attitude stability and then proceeding into short flights with lots of room around it. A contingency plan for losing control must be in place, i.e., have something you can hide behind if everything goes wrong.

Another thing that comes to mind since you mentioned the multiranger is making sure your ranging sensors are not blocked in any way.

Perhaps you should post some data of your system such as mass, prop size and pitch, motor kV, shaft to shaft distance, etc. Someone may have assembled something similar.

Re: BigQuad Unstable - Constantly changing values for roll\pitch

Posted: Fri Sep 20, 2019 9:41 pm
by Lombazombie
Hello ricardo.halfeld,

Deeply sorry, we completely rebuild the drone and have been doing work with the smaller crazyflie.

We haven't been able to get it any more stable then before. Even with PID tuning we are able to get it to lift but it will lean towards one direction. ANy ideas why that may be the case?

Also although we have been doing PID tuning. Any advice or recommendation for readings or how to do it?

I should be able to post pictures and info on monday. We are not using the multiranger anymore and have been using the flow deck but we are going to remove it..

Thank you.