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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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is crocoddyl a library of iLQR based solver or DDP based solver? #749

Closed ddliu365 closed 4 years ago

ddliu365 commented 4 years ago

It seems this solver only used the first derivatives of the dynamics instead of second derivatives which should be included in DDP.

cmastalli commented 4 years ago

We use only the Jacobian of the dynamics. It is equivalent to an iterative LQR algorithm.

Despite that, we prefer to think that our solver it is a DDP algorithm with Gauss-Newton assumption.

cmastalli commented 4 years ago

Crocoddyl has different solvers. One of our novel solver is called feasibility-driven DDP which it is a remarkable improved version of the DDP algorithm.

Additionally, our DDP algorithm is not exactly the classical implementation. We make a relinearization of the Value function to be able to accept the state trajectory as warm-start.

For more details see the Crocoddyl paper described in Readme file.

cmastalli commented 4 years ago

I will close this issue.

Feel free to ask further questions in other issues.