Disturbance observer and prescribed time controller

Hi, I simulated a disturbance observer based prescribed time controller, but I'm facing two problems : 1- When I choose a really small Tfc in the follwoing code, a singularity is resulted in the second state.

Answer 1

[CHANDRA BABU GUTTIKONDA]

Prescribed-time terms 1/(Tfc−t)1/(T_{fc}-t)1/(Tfc​−t) blow up near TfcT_{fc}Tfc​ in discrete simulation, creating an impulsive control that drives x2x_2x2​ unstable.