Fixing bug in the computation of the SE3's residual and its derivaties

[wxmerkt]

In GitLab by @cmastalli on Nov 16, 2018, 12:31

null

[wxmerkt]

In GitLab by @cmastalli on Nov 16, 2018, 12:45

The residual vector represents the local velocity of the frame expressed in the reference frame, i.e. d^V^f where d is the reference frame and f the local frame (see https://gepgitlab.laas.fr/loco-3d/cddp/blob/devel/cddp/costs/multibody_dynamics/se3_cost.py#L41).

Instead the Jacobian of the residual is expressed in the local frame, i.e. f^J^f (see https://gepgitlab.laas.fr/loco-3d/cddp/blob/devel/cddp/costs/multibody_dynamics/se3_cost.py#L45).

I suggest to express the local Jacobian in the reference frame d^J^f = d^X^f * f^J^f. So we need to get the frame Jacobian in the local frame and them map it through d^X^f. Note that we can compute it as d^X^f = inv(0^X^d) * 0^X^f.

[wxmerkt]

In GitLab by @cmastalli on Nov 16, 2018, 13:49

assigned to @cmastalli

[wxmerkt]

In GitLab by @cmastalli on Nov 16, 2018, 14:05

mentioned in merge request !15

[wxmerkt]

In GitLab by @cmastalli on Nov 19, 2018, 09:27

The task was tackled in !15. I am closing this task!

[wxmerkt]

In GitLab by @cmastalli on Nov 19, 2018, 09:27

closed

[wxmerkt]

In GitLab by @proyan on Jan 2, 2019, 15:34

Thanks for the correction.

Currently, we are doing moving the jacobian from the world to the local frame (when we call the pinocchio function 'getjacobian'), and then we are moving from the local to the desired frame.

This is just a minor point, but it would be faster to compute in the world frame, then apply the action matrix to move the derivative from the world to the desired frame.

[wxmerkt]

In GitLab by @proyan on Jan 2, 2019, 15:34

reopened

[wxmerkt]

In GitLab by @nmansard on Jan 21, 2019, 15:24

This is solved by refact. I am closing.

[wxmerkt]

In GitLab by @nmansard on Jan 21, 2019, 15:24

closed