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loco-3d / crocoddyl

Crocoddyl is an optimal control library for robot control under contact sequence. Its solver is based on various efficient Differential Dynamic Programming (DDP)-like algorithms
BSD 3-Clause "New" or "Revised" License
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DifferentialActionModelFreeFwdDynamicsTpl does not update data.pinocchio #1119

Closed huweiATgithub closed 1 year ago

huweiATgithub commented 1 year ago

In the following code snippet: https://github.com/loco-3d/crocoddyl/blob/0500e398861564b6986d99206a1e0ccec0d66a33/include/crocoddyl/multibody/actions/free-fwddyn.hxx#L124-L127

The derivatives are stored (expect ddq_dtau=Minv) in d->Fx instead of d->pinocchio, which makes it impossible for Cost Models to re-use these derivatives.

Any suggestion on that? Is there a workaround, or should we do the computation of the derivatives in each cost model that needs it?

cmastalli commented 1 year ago

Hi @huweiATgithub,

These derivatives cannot be stored in Pinocchio as they do not represent what you meant.

However, you can always access the individual terms (i.e., Minv and dtau_du) in your cost function via the respective collector.

huweiATgithub commented 1 year ago

Thank you. I need also ddq_dq and ddq_dv, which can be stored in Pinocchio. (e.g. another overload version of computeABADerivatives)

cmastalli commented 1 year ago

The ABA derivatives are already stored in Pinocchio data, which you can also access via the collector.

huweiATgithub commented 1 year ago

I checked the data. It is not saved in Pinocchio data due to the overload of computeABADerivatives Crocoddyl is calling (they are stored in the reference passing in instead).