How to change the parameters of step function?

Hi, I have this transfer function: >> num=[122.1]; >> den=[1,3,3,1]; >> G=tf(num,den)

G =

          122.1
  ---------------------
  s^3 + 3 s^2 + 3 s + 1

i usually plot the step function as >>step(G) But in this case, I want to know the step response with these specifications: Inicial value= 28 Final value=70 Rise time=20

If i specify this parameters as: requirement = sdo.requirements.StepResponseEnvelope('FinalValue',70,'InicialValue',28,'RiseTime',20)

How could I affect step function with the last parameters? Thanks

Answer 1

[Star Strider]

Using stepDataOptions (link) you can change the amplitude and the offset, but nothing else. So you can specify everything except rise time.

You would have to create your own function to generate that input.

Something like this will get you started:

t = 0:99;
u = (2.1*t + 28) .* ((t >= 0) & (t<= 20)) + 70.*(t>20);

Plot it, then make any necessary changes to get it to work with your transfer function.

[Daniela Montserrat Ruiz López]

Thank you very much

[Star Strider]

As always, my pleasure.