Hey guys. Anyone know how to get the inertia tensor of a bunch of masses in a tree?
Right now I’m just adding all the individual inertia tensors. I can’t find any clear explanations
What you’re looking for is the “Parallel Axis Theorem.” It lets you sum various inertias (second moment thereof) and it’s quite simple.
Essentially you can shift the second moment of inertia in one direction (let’s say the x, y and z axes) to a new reference point. Once all second moments of inertia are all in relation to the same point, they can be summed together.
https://en.wikipedia.org/wiki/Moment_of_inertia#Parallel_axis_theorem (Pretty poor source of info unless you’re at a far, far higher level of understanding of mechanics than me but even I was able to get the basics.)
Ahh yea that’s it.
I remember this now from a physics class freshman year.
Thanks!
Ditto.
It’s that one thing which you never need again until suddenly you need it again.