How Do Bode Plots Help in Designing Controllers for Liquid Level Management?

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topcat123
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Homework Statement


This is the second part my problem. In the first part the Open Loop and Closed loop TF where worked out from design parameters. In later questions a lead or lag commentator is needs to be designed.

Design an appropriate controller to ensure the steady state
error in the liquid level in the tank when it undergoes a step
change is always less than ±0:5%. The settling time and
overshoot of the system response should also be less than
1:5 seconds and 5%, respectively.

I am unsure on how to calculate these parameters.

Homework Equations


The system is a negative unity feedback.

The Attempt at a Solution


Open loop TF
$$G(s)=\frac{0.213}{s(0.66s+3.5)+1}$$
Closed Loop TF
$$G(s)=\frac{0.213}{s(0.66s+3.5)+1.213}$$

Using the Steady Stat Error ##(e_{ss})=0.005##to work out the gain for the controler
$$e(s)=\frac{R(s)}{1+KpG(s)}$$
With A step ##\frac{1}{s}##
$$e(s)=\frac{\frac{1}{s}}{1+KpG(s)}$$
As ##\lim_{ss \rightarrow \infty} e(t)=\lim_{s \rightarrow 0} se(s)=0.005##
##s=0##
Therefor
$$0.005=\frac{s\frac{1}{s}\left[s(0.66s+3.5)+1\right]}{s(0.66s+3.5)+1+0.213Kp}$$
Giving A ##Kp=934.27##
How do I calculate the rise time, peak overshoot and the settling time.

Any tips or help would be appreciated.
Thanks
Tim
 
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Plot it how? Bode, Root locus.
 
topcat123 said:
Plot it how? Bode, Root locus.
No. Plot the response signal versus time. Feed a step function into the transformation and measure how it responds in time. All the requirements you listed in your post #1 can be measured by looking at the plot of response versus time.