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Neuroadaptive observer design for spacecraft attitude control and formation attitude synchronization
Subedi, Garba
Subedi, Garba
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2020-12
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Abstract
Spacecraft attitude-tracking control problems require uncertainties and disturbances-
rejecting controllers to perform well in practical scenarios. The objective of this research is
to design an adaptive controller that uses Modi ed State Observer (MSO) to improve upon
the controller's performance for spacecraft attitude-tracking. The application scope of the
MSO-based control strategy is then extended for attitude synchronization problems.
In this thesis, a spacecraft is considered to be operating under in
uence of unmod-
eled system dynamics and external disturbances. The e ects of these factors are modeled
as an unknown angular acceleration function, which is predicted by using an observer that
depends on a neural network. The rst part of this research is focused on augmenting
a classical inverse controller with an MSO observer (i.e. unknown function estimating ob-
server). Chebyshev neural network is employed in designing the MSO such that the unknown
function prediction performance is enhanced, which consequently enhances attitude-tracking
performance. To validate the controller's enhanced performance, two numerical examples are
presented to highlight the di erences in performance of the proposed versus existing con-
trollers.
In the second part of the research, the proposed attitude controller is augmented to
solve attitude synchronization and stabilization of spacecraft in a leaderless formation-
ying
network. The communication time-delay, which is inherent and unpreventable, is considered
in the course of designing attitude-synchronizing controller. The proposed methodology em-
ploys a graph theory-based model for the communication network to determine a desired
angular velocity pro le, which guarantees angular velocity stabilization and attitude consen-
sus among spacecraft. The MSO-based inverse controller drives the angular velocity error
and attitude error to zero such that the desired reference pro le is attained. Two numeri-
cal examples are presented to validate that the controller is able to reject disturbances and
uncertainties while achieving attitude synchronization.
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Thesis (M.S.)-- Wichita State University, College of Engineering, Dept. of Aerospace Engineering
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Wichita State University
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© Copyright 2020 by Garba Subedi
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