$\begin{cases}\frac{\mathrm{Ls}}{1+e^{-80(t-\mathrm{ts}-0.05)}} & \text{if $(t< \mathrm{ts}+0.15)\land (t\ge \mathrm{ts})$}\\ \mathrm{Ls} & \text{if $t\ge \mathrm{ts}+0.15$}\\ 0 & \text{otherwise}\end{cases}$