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

AI Thread Summary
Bode plots are essential for designing controllers in liquid level management as they help analyze system stability and performance. The discussion focuses on ensuring a steady-state error of less than ±0.5% and achieving a settling time under 1.5 seconds with less than 5% overshoot. The user has derived the open-loop and closed-loop transfer functions and calculated the proportional gain needed for the controller. To evaluate performance metrics like rise time, peak overshoot, and settling time, it is suggested to plot the system's time response to a step input rather than relying solely on Bode or root locus plots. The key takeaway is that time response plots provide direct insights into the system's dynamic behavior and performance.
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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The only thing I have ever seen is to plot its time response to a step input and determine those numbers from the graph.
 
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.
 
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