Question

I have G=1/(s*(s+3)*(s+4))
and K=0.5

We need a closed loop system so :

V=feedback(G*K,1)
sisotool(V)

Now I have the plots on the screen, if I go to :

Analysis > Response to Step command

I get the closed loop response to a step input, but what about ramp ?

Where in Sisotool can I find a response to a ramp ?

Thank you very much !

Answer 1

There is no ramp response in sisotool. If you recall, the Laplace transform of a unit ramp input is 1/s^2. Therefore, you need to add an integrator (1/s), and use the step response (which has a Laplace transform of 1/s). I normally add the integrator outside of the loop in the “F” block, and that gives me the unit ramp response.