In the following equation for the Rigid Body total momentum derivate
I think there are the two following typos:
in the second equation, the wrenches should be expressed as $_{G[A]}f\^x$ (in $G[A]$ reference).
in the third equation the rotation matrix $^ARG^T$ should not be present since it cancels out after multiplying by $\{G[A]}X^B$.
in the second equation I think it would be also good to express respect to which frame $g$ is defined, and to specify the rotation matrix $R^T$ where is defined (${R^T}g \to {^AR_G^T}^Ag$)
In the following equation for the Rigid Body total momentum derivate![Screen Shot 2019-08-30 at 12 01 47](https://user-images.githubusercontent.com/35487806/64012496-1bf4db80-cb1e-11e9-8b35-3687790e0ca7.png)
I think there are the two following typos: