Difference between poses

I'm working with the poses on Ros.

pose1 = tf_conversions.Frame ()
pose2 = tf_conversions.Frame ()

the expression (pose1 * pose2.Inverse ()) is equivalent, if I understand correctly, to pose1-pose2 .. What does (pose1 * pose2.Inverse ()). Inverse()?

Solution

Let's say A and B are the two poses:

$A = \begin{bmatrix} R_1 & t_1\\ 0^T & 1 \end{bmatrix}, B = \begin{bmatrix} R_2 & t_2\\ 0^T & 1 \end{bmatrix}$

To get the difference pose different between A to B we can define as

$AB^{-1}$

How can we define between B to A? that's what you are looking for

(pose1 * pose2.Inverse ()). Inverse()

In other words,

$(AB^{-1})^{-1} = BA^{-1}$