Graph behaviours in Simulink

I need response of a system. Modified some blocks but response is not fit to time characteristics.

attached simulink file. *coefficients are not important.

Answer 1

[Jon]

I don't think you should be using the derivative block. I don't see that in the original diagram. Also it makes no sense to differentiate a step function, the result would be infinite (theoretically an impulse, but Simulink will only approximate this).

Also I'm not sure what you mean by "the coefficients are not important". The shape of the responses will of course be highly dependent upon the coefficient values that you choose.

Since everything is linear if you have the control systems toolbox, you don't even need to use Simulink for this. You can just set up your system by interconnecting transfer functions.

[EuroLion]

Jon thank you for your answer. Yes you are right there is no derivative block. But I wanted fit curve. coefficients are important but they are variable. I have no information about it. That affects shape of response. Now I will try get along with control systems toolbox.

[Jon]

It is also OK to do it in Simulink if that is helpful, Simulink can solve purely linear systems too, its just not needed as it would be if you were looking at non-linear effects, like actuator saturation etc. An advantage to doing it with the control systems toolbox is that the ode's do not need to be solved numerically with any associated numerical issues with time step sizes etc.