522 Chapter 20 Three-Dimensional Kinematics and Dynamics of Rigid Bodies
Space and Body Cones
Z
A way to visualize moment-free Z Space
steady precession. The space Space u cone
u cone
cone is fixed in space. The body
cone rolls on the surface of the z
y z
b
space cone. The precessing
object undergoes the same f
b
motion as the body cone. The
Body
angle b is related to the nutation
Y cone
angle by
Izz
tan b # ! "
Ixx
tan u. Body
cone
c x
X
Z
z
u Space
b cone
y
If b $ u, the interior surface of
the body cone rolls on the
exterior surface of the space
cone.
Y
Body
cone
c x
Euler Angles for an Arbitrary Object
Z, z Z , z!
y!
Y, y Y
The xyz coordinate system is body
fixed and aligned with the primary X, x X c x!
XYZ coordinate system in the initial
(a) (b)
orientation (a). The precession
angle c is a rotation of the object
about the Z axis (b). The nutation Z , z! y
y" y"
angle u is a rotation of the object
about the x¿ axis (c). The spin angle
z", z x
f is a rotation of the object about u
the z– axis (d). z"
y!
f
Y
x"
X c x!, x"
(c) (d)