What is the capability of the control loop to compensate offset in measurement?

45 Views Asked by At

Let's say I have a control loop

enter image description here

where $D$ is the transfer function of the controller and $G$ is the transfer function of the plant. The $R$, $Y$, $E$, and $V$ are the Laplace transforms of the reference value, the controlled variable, the control error and the measurement noise. As far as the Laplace transform of the control error following equations hold

$$ \begin{eqnarray} Y &=& \frac{DG}{1 + DG}\cdot R - \frac{DG}{1 + DG}\cdot V \\ E &=& R - Y = \frac{1}{1 + DG}\cdot R + \frac{DG}{1 + DG}\cdot V \end{eqnarray} $$

Now suppose there is a constant offset in the measurement i.e. $V = \frac{1}{s}$. My question is whether the control loop can compensate this offset in case following holds $\lim\limits_{s\to 0} (DG) \to \infty$?