[wenc]

On the contrary, ZN is taught is almost every undergrad control course — and not actually used industry. It’s a classic textbook method to demonstrate the concept in simulations but it has many downsides in practice (pushing the system to its boundaries is not a good idea).

Most professionals tune with starting values obtained using model inversion (IMC, direct synthesis) and then hand tune. There is also software like Loop Pro that analyzes the data and proposes tunings.