[ros-users] Draft REP: Coordinate Frames for Humanoids Robots

Matthieu Herrb matthieu.herrb at laas.fr
Thu Jan 12 09:01:19 UTC 2012

On Wed, Jan 11, 2012 at 12:06:54PM +0100, Thomas Moulard wrote:
> Hi all,
> Attached is a draft defining naming conventions and semantic meaning
> for coordinate frames of legged robots used within ROS.

A couple of small nits...

> left_hand and right_hand
> ''''''''''''''''''''''''
> The coordinate frame called ``left_hand`` defines the position and
> orientation of the left arm end effector.
> If the end effector is a grasping device, the frame should be located
> at the recommended object grasping location. The frame orientation is
> defined as X the axis which should be collinear with the object axis
> during the grasping process, Y the axis going "toward" the reached
> object and Z the axis orthogonal to the (X,Y) plan.
> The coordinate frame called ``right_wrist`` defines the equivalent
> frame for the right arm.
> Frame Authorities
> -----------------
> Unlike mobile bases, the transformation from ``base_link`` to
> ``base_footprint`` is not rigid on humanoid robots and is broadcasted by
> an external node.

Rigidity is also not always true for mobile platforms. Especially
outdoor chassis with suspended wheels can have home complex
geometrical transformation here, which can't always be approximated as
a constant...

Matthieu Herrb

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