Pre-scaling in acados

User Questions
1

Hi all,

I would like to know if there is pre-scaling in acados implemented. To maximize the accuracy of the result?
Since I have two values with very different magnitudes as targets in my cost function. (one force (1e4 Newton) and one angle (1e-2 rad)).

Best regards,
Freddy

2

Hi,

there is no pre-scaling implemented in acados.
So, it is in responsibility of the user.

I see that different magnitudes in the formulation can lead to inexactness.
But I would guess that there are no huge issues with the magnitude difference you are mentioning.

Also, if there is such a pre-scaling procedure for similar software projects, I would be interested to have a look.

Best,
Jonathan

3

Hi Jonathan,

yes, you where right. The solution was to adopt the weights considering the differences of magnitude in the reference signal and set “nlp_solver_exact_hessian” to true.

I know that the osqp solver https://github.com/oxfordcontrol/osqp is using (pre-) scaling, as it is mentioned in its paper.

Best regards,
Freddy