So i am writing about AI and what AI are being used for in aircrafts, like autopilot. But I need to know how the autopilot really work. I came across something called VANAV and LNAD. That should be something the autopilot is using. But I cant find a description about how the autopilot really works, what parameters etc it is using to navigate. I dont know anything about airplanes (mostly) so i am looking for a link to a site that can describe it or a person who are willing to explain it !!
Ohh and i choose to write about A320 since i read that should be one of the most used aircraft including being better then the B737.

BUT i need to know it before this Friday!