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BigQuad Unstable - Constantly changing values for roll\pitch

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

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.

Thanks.

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.