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GeorgeBoutselis / DDP-LieGroups

Differential Dynamic Programming on Lie groups
MIT License
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Second order derivatives f_{xu},f_{uu} are all zeros #1

Closed chenghuailin closed 5 months ago

chenghuailin commented 6 months ago

I've checked and run the codes and it works so far. However, I've also gotten an problem about the linearized dyanmics.

In lineardynTSOeul.m where the Jocabian and Hessian is obtained, two of three the second order derivative of dynamics, he f{xu} and f_{uu} are all set to be zero. To further confirm, I printed out those variables and they are indeed all zeros.

Are you sure this is the right way, or is it a unfinished version of code? For me, it seems a bit wierd that they are all zero, seemingly saying the changes of the input doesn't affect the dyanmics at all. If I'm wrong, can you explain a bit about that?

GeorgeBoutselis commented 5 months ago

These are Hessians. It just follows by taking consecutive derivatives of the example posted here. f_{u} is not zero though.