[Filligree]

As someone who's only worked with PID controllers, do you have any pointers to the more complicated stuff you're thinking about? A wikipedia article maybe?

[regularfry]

It's been a while, but I remember https://en.wikibooks.org/wiki/Control_Systems/MIMO_Systems#S... as a fair example. State-space representation is very powerful, and totally unnecessary for PID.

[nuclearnice1]

Try Model predictive control (MPC) and linear quadratic regulator (LQR)