Drone Physics

> This article describes drone physics. Audience should have familiarity with introductory linear algebra, introductory calculus, and introductory classical mechanics.

Having familiarity with all 3, as soon as I read this sentence I knew it was all down hill for me.

If you're into simulators then you may try applying forces directly rather than integrating ODE. If sim's has tiny numerical instabilities or integrator schedule is wrong the whole thing gonna fall spectacularly. The interest is with running large-scale simulations where along with ODE you need to handle collisions and deformations. The best one currently is MuJoCo.

I studied this subject when I was building FPV sim from scratch. I noticed that yaw action is often misunderstood, falsely believing that it's caused by a change in angular momentum (think reaction wheels).

There is a good SE answer about deriving net torques given each props' thrust force in less PhD language than this article: https://drones.stackexchange.com/a/416/11402

If anyone is interested in tackling UAV simulation, make sure to check out this prop/motor performance database, helped me a lot building a virtual drone with realistic properties (mainly motor thrust & torque): https://database.tytorobotics.com/tests

This feels very https://ciechanow.ski/

Which I think is a good thing :)

I was looking for an explanation of how you deal with the fact that quad rotors are under-actuated, and therefore you lack the complete control authority to do any arbitrary motion in space. So path planning has to take this into account, but how is this described?

I wrote something similar (though admittedly more in depth) some time ago: https://www.cggonzalez.com/blog/index.html

Previously: https://news.ycombinator.com/item?id=48781539

I would have liked to understand this, but the math behind it is overkill. One may need a PhD in aerospace to digest it.

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