I don't know if it's important but the channel of the stanford university in youtube has a good collection of robotics course
I've seen Course | Introduction to Robotics with 16 full lecture videos (but I did only see the first 3) and there are videos of other courses as well (example: modern physics, and interesting for games the course of machine learning, and some programming courses)

to matrices, I have to admit that I didn't understand for so long time matrices until I've red a chapter of an directx8 book of gallileo press(only german) It's a really bad and to simple book ( you don't learn much you do what he want lol) but I found the matrices explenation there really good. maybe sometimes the simple things are better than the professional super infos hehe
but I admit too that I still forget sometimes the order of which matrices comes first in an computation. so I end up to cursing with my pc and finally google and then tell myself you idiot It's so simple hahaha

this said, have a good start into the new week guys byeee

ps: Inverse Kinematics is a big topic there at the videos