Asking about the ''delayss'' function in matlab

Hello, I am using the ''delayss'' function to simulate a delayed statespace system. my question is , it is written in the command line after I obtain the system matrices A,B,Cand D that '' (values computed with all internal delays set to zero). does this mean that the resulted statespace matrices don't represent the delay inside the system that I already introduced in the 'delayss' function ?

Answer 1

[Paul]

Hi Mohamed,

Not sure if this answers your question, but ...

The state space matrices shown in the output after using delayss at the command line are exactly what the output says they are: the state space matrices of the model assuming the delays are set to zero. But the output also tells you what the delays actually are in the model. And we can see that the delays do affect the output.

DelayT(1) = struct('delay',0.5,'a',0,'b',2,'c',1,'d',0);
DelayT(2) = struct('delay',1.2,'a',-1,'b',0,'c',0,'d',0);
sys = delayss(-1,1,1,0,DelayT)

sys =
 
  A = 
       x1
   x1  -2
 
  B = 
       u1
   x1   3
 
  C = 
       x1
   y1   2
 
  D = 
       u1
   y1   0
 
  (values computed with all internal delays set to zero)

  Internal delays (seconds): 0.5  0.5  1.2 
 
Continuous-time state-space model.

sysnodelay = ss(-1,1,1,0)

sysnodelay =
 
  A = 
       x1
   x1  -1
 
  B = 
       u1
   x1   1
 
  C = 
       x1
   y1   1
 
  D = 
       u1
   y1   0
 
Continuous-time state-space model.

step(sys,sysnodelay)

[Mohamed Abdullah]

Thanks Paul, This is pretty helpful . I was very confused. I thought since the delay is not included in the process of calculating the matrices, then how the delay is considered in the output system matrices.

The last line is what I needed to read '' But the output also tells you what the delays actually are in the model''.

Thanks again.