How to get terms required for DDP

[lwygzh]

Hi,

Thank you for open sourcing this library!

I am new to this library, I was wondering after creating the robot model using

robot = pinocchio.robot_wrapper.RobotWrapper.BuildFromURDF(urdf_path)

could I get the functions $x_{n+1} = f(x_n, u_n)$, $\displaystyle\frac{\partial f}{\partial u}$, $\displaystyle\frac{\partial f}{\partial x}$, $\displaystyle\frac{\partial^2 f}{\partial x\partial x}$, $\displaystyle\frac{\partial^2 f}{\partial x\partial u}$ and $\displaystyle\frac{\partial^2 f}{\partial u\partial u}$ using pinocchio?

[stephane-caron]

The answer to your question, where $f$ is the forward dynamics function of your system, is yes. You can look for instance at Crocoddyl, which implements DDP using Pinocchio. You can also look at the forward-dynamics-derivatives.cpp or forward-dynamics-derivatives.py examples.

[lwygzh]

Thanks for the response!