# Quiz 2: Closed-Loop Control

## 8 thoughts on “Quiz 2: Closed-Loop Control”

• Also, can you open the drop box so we can turn the quiz in early without having to wait until the day before its due?

• It says so in Task 3. You *may* use $k_p$ if you wish in Task 2, but my initial intention was that you use $H(s)$. It does not make a difference.

1. When solving for w(t–>infinity), does the R ‘disappear’ if we assume kp is large, such that we are left with: r + 1/(kmkp)*d ???

• No and yes. No, $R$ does not disappear, but it becomes very small compared to $k_p$. For large $k_p$ the factor in front of $r$ nears unity. Also, while $r + 1/(k_M k_p) d$ looks good, provided that you assume $R$ is small compared to $k_M k_p$, but you can make the point that with $k_p \to \infty$ the factor in front of $d$ goes to zero.

In either case, I have the impression that you are on the right track.

2. The closed-loop system is one where the output signal (i.e, the controlled variable) is in some fashion fed back into the controller and leads to a control action.

Conversely, the open-loop system is where the feedback loop is opened at some point, which means that no control action can take place. An open-loop configuration is useful to determine the behavior of the underlying system without active control.

See, for example, Section 5.3 in our book, especially Figure 5.3.