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In recent years, there has been a tend toward larger and larger
spacecraft. At the same time, the mission requirements are more
and more complex satisfy all kinds of requirements, the power
required in the spacecraft is increased. In other words, the
orientation of large flexible solar panels should be controlled
to provide enough power without influences on the pointing
accuracy of the payload. That is, an active control should be
used to achieve all kinds of tasks with good vibration
suppression. Early spacecraft were mostly rigid, and their
attitude motion was controlled by passive means, such as spin
stabilization or gravity-gradient stabilization. Meirovitch, L.
did the firdt works in which the equations of motion of
spinning spacecraft considering of a rigid body with flexible
appendages were derived. About the same time, in the mid-1960s,
a formalism was being developed for deriving the attitude
equations of motion of a spacecraft consisting of a number of
interconnected rigid bodies arranged in a "topological tree."
The formalism was extended to the case in which the
interconnected bodies were flexible and to the case in which
the sapcecraft is stabilized by means of active control.
Another approach to the derivation of the equations of motion,
suitable not only for spacecraft structures but also for
aircraft and civil structure, is known as component-mode
synthesis or substructure synthesis. This approach regards the
structures as collection of substructures, eash one
represented by a limited number of degrees of freedom. Hence,
the method represents not only a modeling technique but
trunction procedure as well. It should be observed that the
approach of Ref. 1 can be regarrded as an example of
substructure synthesis.
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