[Bug Report] Frame transformation docstring notation

[mis0butter]

Describe the bug

Update docstring for combine_frame_transformations and subtract_frame_transformations inside isaaclab.utils.math, specifically this misleading part:

where :math:T_{AB} is the homogeneous transformation matrix from frame A to B.

In the explanation, A and B should be swapped:

T_{AB} is the homogeneous transformation matrix from frame B to A.

Additional context

For the frame transformation T_AB, saying "from frame B to A" is equivalent to saying "frame B with respect to A," also commonly "of B in A." Or, in other words, the "orientation of frame B measured in frame A."

This is standard, although it can differ based on kinematics conventions. It looks like Isaaclab uses this convention, because in the same docstring, it says:

t01: Position of frame 1 w.r.t. frame 0. Shape is (N, 3).
q01: Quaternion orientation of frame 1 w.r.t. frame 0 in (w, x, y, z). Shape is (N, 4).

which follows the T_AB = "from B to A" convention.

Source

Tedrake, R. (2023). Robotic Manipulation. Course Notes for MIT 6.4210. Chapter 3: Basic Pick and Place. Section 3.1: Kinematics. https://manipulation.csail.mit.edu/

Checklist

• I have checked that there is no similar issue in the repo (required)
• I have checked that the issue is not in running Isaac Sim itself and is related to the repo

Acceptance Criteria

Add the criteria for which this task is considered done. If not known at issue creation time, you can add this once the issue is assigned.

• Updated for combine_frame_transformations
• Updated for subtract_frame_transformations

[RandomOakForest]

Thank you for posting this. The team would appreciate if you could submit a PR. Thank you.

[mis0butter]

Created PR here: #5819