Some explanation about AUTO mode?

Hi everyone !

This summer in my college, I will be in a team that builds quadricopters for a competition. I have been asked to work on the ArduPilot code and have to explain how it works, for us to know how to make changes in the code.

I have been working on that for a week now and have understood a good part of the code but I still have some difficulties to understand how does it run when used in Auto mode. The code is very dense and I can’t figure it out.

More precisely, I would like to know two things :

  1. How does the drone knows his position ? Does it use GPS combined to intertial sensors ? When, in the code, is this updated ?
  2. What is the global logic of the waypoint navigation ?

I am not looking for someone to work for me. I just need to be shown where to look or to be given some documentation that could be useful.

Thank you for your help ! And sorry if my english is strange, I am not a native speaker :slight_smile: