Implementing rate constraints and rate costs

[FreyJo]

Hi Martin,

@martiabr

I know this could be achieved by augmenting the dynamics or adding the dynamics function as x_dot in the cost function / path constraints, but that would increase the number of variables or complicate the NLP a lot, so it would not be ideal.

Reformulating your system to have u as a state and \dot{u} as the new control would probably be the way to go.
In typical optimal control problem formulations, there is no coupling of the control inputs.
Since acados is tailored to exploit the typical optimal control problem structure, this is not supported.

@martiabr

It seems to me like each stage cost is completely separate from each other, making this impossible, is this indeed the case?

Yes, the stages are only coupled trough the model dynamics.
Sorry, if this is not ideal for you.
But I hope you can still get good enough performance in acados using this reformulation.

Cheers,
Jonathan