  Complex multibody legged robots can have complex rotational control
challenges. In this paper, we propose a concise way to understand and formulate
a \emph{whole-body orientation} that (i) depends on system configuration only
and not a history of motion, (ii) can be representative of the orientation of
the entire system while not being attached to any specific link, and (iii) has
a rate of change that approximates total system angular momentum. We relate
this orientation coordinate to past work, and discuss and demonstrate,
including on hardware, several different uses for it.
