I have the next system, and I want to find the transfer function from d to y.
So I've got the next equations
$$v = Ce = C(r-y)$$ $$e = r - y$$ $$u = d + v$$ $$y = Pu = Pd + PCr - PCy$$
Now I know that:
$$e/r = \frac{1}{1+PC}$$
So eventaully if I am not mistaken I arrive at:
$$y/d = \frac{P}{1+PC}+\frac{PC}{1+PC} \frac{r}{d}$$
How do I eliminate the dependence on \$r/d\$? i.e, I want y/d to be a function of P and C.
Edit: actually, I arrive at:
$$ y = \frac{P}{1+PC} d + \frac{PC}{1+PC} r$$
So the transfer function from d to y should be: \$\dfrac{P}{1+PC}\$, correct?