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In this thesis, we study the problems of missile interception
and soft landing on an asteroid. First we employ
linear stability theory to design guidance control
laws for missile interception problem. Lyapunov
approach is then used to enlarge the capture region. However,
for the case of large capture distance and/or maneuvering
target, such a guidance control law is found to
fail to intercept the target. Variable structure
control type guidance laws are proposed to
tackle the problem. This is achieved by
treating the maneuver motion of the target as unmodeled dynamics
and suitably selecting the sliding surfaces. Moreover, feedback
linearization type control laws are also proposed for
missile interception. These two control schemes are shown to
be effective in intercepting both non-maneuvering and
maneuvering target. Same approaches are then employed to design
the guidance control laws for the soft-landing on an asteroid.
The main difference between interception and landing problems
is that both aero-drag and gravitational force are concerned
in landing problem but not in missile interception.
Numerical simulations are presented to demonstrate the main
results, which show that feedback linearization type guidance
control laws provide better performance in both missile
interception problem and the soft landing on an
asteroid.
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