Modelling an S-shaped Second Order Response

55 Views Asked by At

I am trying to model an S-shaped second order process response as a transfer function in Simulink, as shown in Figure 3 in the linked article. Ideally the response should be overdamped. I have tried using the function: $\frac{1}{s^2 + 5s + 1}$ however my process response is non-S shaped. Could you please give me advise on how to adjust my transfer function such that it emulates the figure in the article?