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I am using the PID Tuner for the PID Controller Block in Simulink. I am particularly interested in the output disturbance BODE plot. I am trying to achieve an acceptable output disturbance with the follow requirements:

  1. Attenuation of at least 10 dB with frequencies less than 0.5 Hz

  2. Flat response (0 dB) at higher frequencies with no overshoot.


By raising the bandwidth of the controller, see image below.

raising the bandwidth of the controller

I am able to achieve the appropriate attenuation at < 0.5 Hz, but I am getting a nasty overshoot at 4 Hz, which is unacceptable. Lowering the bandwidth, see image below, removes the overshoot but then I have poor attenuation.

Lowering the bandwidth


My plant is:

\$G(s) = \frac{4.1s + 59.5}{s^2 + 34.1s + 385.7}×e^{-0.05s}\$

Other than adjusting bandwidth and phase margin, is there anything else I can try to achieve both of these requirements?

If it isn't evident. I am not an expert in controls engineering. I apologise in advanced if this question seems novice.

Thank you,

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  • \$\begingroup\$ I like the linking to gyazo, it shows that you're rebellious. \$\endgroup\$ – Harry Svensson Aug 5 '17 at 2:39
  • \$\begingroup\$ @HarrySvensson Did I break any forum rules? I am unaware. \$\endgroup\$ – gelman_grad Aug 5 '17 at 2:43
  • \$\begingroup\$ My point is flying too high, what I'm saying is that it's unnecessary to be sloppy. If a question asks for people to click links and decipher what your question really is about, 99% of them will give up. If you however present it like x-3 = 0 where you see the question and the problem instantly, then you'll receive proper answers. And the thing with gyazo is that there's already a built in image uploader here at stackexchange because a question should be able to stand on its own. I'm not trying to be mean, just giving some advice, don't take it the wrong way. It's a good question. \$\endgroup\$ – Harry Svensson Aug 5 '17 at 3:51
  • \$\begingroup\$ Google 'Smith Predictor Controller' \$\endgroup\$ – Chu Aug 5 '17 at 9:31
  • \$\begingroup\$ @HarrySvensson Thanks Harry, I will keep in mind the etiquette. \$\endgroup\$ – gelman_grad Aug 8 '17 at 18:34

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