Should we have a `base_footprint` TF frame?

[tckarenchiang]

The idea with base_footprint is that it provides a

projection of the robot's base_link "on the ground floor"

Especially for mobile robots this is useful, as their base_link could be anywhere, but many 2D nav systems plan at ground floor level.

Some links:

• base_link to base_footprint transform ?
• REP-120: Coordinate Frames for Humanoid Robots
• Where do I put base_footprint?
• base_link vs base_footprint

And the hector_slam page on the ROS wiki (this one) has a nice diagram:

(base_stabilized is not something we need to add immediately. It's mostly for systems which require the LaserScans to always be in a plane parallel to "the ground")