Brilliant! I pulled your Levenberg-Marquadt branch down, and using that option solved my problem. If I recall correctly, I think IPOPT does something similar to try to regularize the Hessian? Now I’m getting equivalent answers from IPOPT and Acados, which is great. Is the 1.0 you set a binary switch, or can this be applied in varying magnitudes?
As a side note, adding a penalty on u also helped, but took more iterations and also required that I reduce the solver step size. The regularization method solved in fewer iterations with the default step size.
Thanks for putting up with my endless stream of questions! This is a great project, and you’ve been extremely helpful.