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How to change model architecture in controlsystemdesigner

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Hello, I have G rotor transfer function = 1/s^2 , and a PI controller (K rotor), the architecture of the model looks like this:
But in controlsystemdesigner, the architecture is the same, but it doesn't allow me to edit block H as a controller. Only C and F can be controller. How can I change that?
The characteristic equation is the same but I need the 1 zero at 0 only
Thank you
  2 Comments
Fangjun Jiang
Fangjun Jiang on 13 Dec 2023
Edited: Fangjun Jiang on 21 Dec 2023
"The characteristic equation is the same but I need the 1 zero at 0 only"
???
Sam Chak
Sam Chak on 21 Dec 2023
@Nghi, A brief analysis shows that if a PI controller is placed in the feedback loop, the system remains unstable. However, if it is replaced by a PD controller, the compensated system will be stable.
s = tf('s');
%% Rotor dynamics (Plant system)
Gp = 1/s^2
Gp = 1 --- s^2 Continuous-time transfer function.
%% Control gains
Kp = 1;
Ki = 1;
Kd = 2;
%% PI controller
Gc1 = Kp + Ki/s
Gc1 = s + 1 ----- s Continuous-time transfer function.
Gcl = minreal(feedback(Gp, Gc1))
Gcl = s -------------------------- s^3 - 1.11e-16 s^2 + s + 1 Continuous-time transfer function.
step(Gcl, 20), grid on
%% PD controller
Gc2 = Kp + Kd*s
Gc2 = 2 s + 1 Continuous-time transfer function.
Gcl = minreal(feedback(Gp, Gc2))
Gcl = 1 ------------- s^2 + 2 s + 1 Continuous-time transfer function.
step(Gcl, 20), grid on

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Accepted Answer

Aiswarya
Aiswarya on 19 Dec 2023
The blocks as such can't be edited but you can have different initial configurations with controlsystemdesigner using the 'sisoinit' function (https://www.mathworks.com/help/control/ref/sisoinit.html). There are a total of 6 configurations where you have different positions for the controllers. You can create a config object and then open the same with controlsystemdesigner:
initconfig = sisoinit(config_num);
controlsystemdesigner(initconfig);
For more information on supported control architectures you may refer to the following resource: https://www.mathworks.com/help/control/ug/feedback-control-architectures.html

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