Should be able to send feed-forward moments in quadrotor_msgs:SO3Command

[justinthomas]

[kartikmohta]

See d335e018c05069a22f2470ad58aa134aaec5b6ba, we can cherry-pick the commit to master if this is really useful for multiple people.

[justinthomas]

Sweet! This is great, but perhaps we could include snap in the PositionCommand and update so3_control accordingly before fully merging?

[kartikmohta]

So demanding! 😐

[justinthomas]

Sorry :-/ Feel free to merge :-P

[kartikmohta]

Now you've put the snap idea in my head, cannot merge without it 😛

[jsvacha]

What would snap be used to compute? Desired angular accelerations? Is our onboard attitude controller even capable of taking those?

[justinthomas]

@kartikmohta hehe, gotcha!

@jsvacha, yes, angular accelerations. They are required to compute feedforward moments. In the current state, the SO(3) controller doesn't include them but it is a fairly straightforward extension. I'm happy to send some derivations along if that would help.

[sytang]

https://xkcd.com/356/

[jsvacha]

This makes sense. I'd just check the scaling factor on the moments. I made the scaling factor so that the moments would be what I expected to see caused by drag during forward flight, and I'm fairly confident that you want a larger range than that, especially if you want to do flips and such.

[justinthomas]

Ahh, yes. Good point. Since the scaling factor is particular to the hummingbirds, we can determine the full range on the moments, so that should help.