I have two subsystems which are shown in the picture below.
One of them is a system of stable and controlled differential equations of a mechanical system.
Second is a block that implements a function $f(\theta)$ from a signal entering its input.
$\theta,\Omega,\omega$ - variables, $u(t)$ - control signal.
I need to combine the two systems in such a way that $\omega=\Omega$. What will be the structure of such a system and how to generate a control signal $u(t)$? As control laws, it is allowed to use simple ones, including $P-$,$PI-$ and $PID-$ones.
I would be grateful to the community for advice and help.