How to change model architecture in controlsystemdesigner

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

[Fangjun Jiang]

"The characteristic equation is the same but I need the 1 zero at 0 only"

???

[Sam Chak]

@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

Answer 1

[Aiswarya]

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