I need to put this block diagram in MATLAB (not in Simulink) and I do not know how to do it

This is the diagram

And this is what I've got so far in code:

s = tf('s');

s1 = tf(1, [1 4]);
s2 = tf(1, 1);
s3 = tf(1, [1 0 9]);
s4 = 10;
s5 = 12;
s6 = tf([1 6],1);

Answer 1

[Paul]

Hi Carlos,

Recheck the definiton of s2. Once you have that taken care of, I suggest you proceed with connect.

[Walter Roberson]

Hint:

1/s is the same as 1/(s + 0)

[Carlos Puente]

I've redefined the blocks as shown in the image to use the connect function in Matlab more easily, but I don't know if what I'm doing is correct.

A.InputName = 'H';
A.OutputName = 'HA';
 
B.InputName = 'F';
B.OutputName = 'BF';

C.InputName = 'BF';
C.OutputName = 'Y';

D.InputName = 'Y';
D.OutputName = 'DY';

G.InputName = 'BF';
G.OutputName = 'GBF';

J.InputName = 'Y';
J.OutputName = 'JY';

S1 = sumblk('E = R - JY');
S2 = sumblk('H = E - GBF');
S3 = sumblk('F = HA - DY');

T = connect(A, B, C, D, G, J, S1, S2, S3, "R", "Y")

[Paul]

That actually looks like it might be correct, assuing that A,B,C,D,G, and J have been defined properly. Can't tell for sure unless you post the complete code. T might be in the descriptor form because J(s) is improper (higher order numerator than denominator), but T can changed to tf or zpk form with tf(T) or zpk(T) respectively, and from there changed back to state space form if desired.

Answer 2

[Sam Chak]

Hi @Carlos Puente

When utilizing the syntax s = tf('s') to establish a special variable 's', you gain the ability to directly formulate rational expressions for the creation of transfer function models. Employing a rational expression proves to be more intuitive, particularly when handling high-order transfer functions. Furthermore, it is advisable to generate dynamical model objects, with the 'tf' class being one of the viable options in this regard.

Proceed as @Paul guided you via the following link:

https://www.mathworks.com/matlabcentral/answers/2030509-i-don-t-know-how-to-introduce-the-block-s-6-in-simulink?s_tid=srchtitle

s   = tf('s');

s1  = 1/(s + 4)

s1 =
 
    1
  -----
  s + 4
 
Continuous-time transfer function.

s2  = 1/s

s2 =
 
  1
  -
  s
 
Continuous-time transfer function.

s3  = 1/(s^2 + 9)

s3 =
 
     1
  -------
  s^2 + 9
 
Continuous-time transfer function.

s4  = tf(10)

s4 =
 
  10
 
Static gain.

s4a = 10        % test subject

s4a = 10

s5  = tf(12)

s5 =
 
  12
 
Static gain.

s6  = s + 6

s6 =
 
  s + 6
 
Continuous-time transfer function.

whos

  Name        Size            Bytes  Class     Attributes

  cmdout      1x33               66  char                
  s           1x1              1281  tf                  
  s1          1x1              1281  tf                  
  s2          1x1              1281  tf                  
  s3          1x1              1297  tf                  
  s4          1x1              1265  tf                  
  s4a         1x1                 8  double              
  s5          1x1              1265  tf                  
  s6          1x1              1281  tf