Hi 
I am struck in one of the formulation using delta u. My model is nonlinear continuous model and I want to introduce deltau for the augmented plant model. Since deltau = uk - u(k-1) and my model is continuous time varying model. One approach I can think is by defining my control variable as a state variable in augemented plant with udot = deru/time_step where deru is the deltau.
I wanted to know whether this approach is correct or is there any other way to do it via acados.
Hi,
if you formulate your system dynamics in continuous time, you need to define an additional state u with dynamics \dot{u} = v where v is a control corresponding to the rate of change in u. You can now add costs/constraints on v.
This approach is also implemented here:
Best, Katrin