Summary: | Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. === Dissertation presented in fulfilment of the requirements
for the degree of Doctor of Philosophy in Engineering
at Stellenbosch University. === ENGLISH ABSTRACT: Airworthiness certification of unmanned aircraft systems (UAS) is normally
considered to be a regulatory function. In the absence of comprehensive UAS
airworthiness regulations, the development of new and unique UAS, and their
introduction into non-segregated airspace, remain major challenges for the UAS
industry and regulators. Thus, in response, the objective of this research was to
establish a framework and guidelines, within the scope of the typical regulatory
regime, that can be used by the UAS engineering domain to ensure the safe and
reliable functioning of a UAS, whether regulated or not.
UAS airworthiness is currently mainly based on manned aircraft regulations, and the
focus is on the unmanned aircraft and the 'airworthiness' of the remote control station.
The typical UAS as a system, however, consists of more than just these elements and
a broader approach to the 'airworthiness' of a UAS is required. This study investigated
and introduces the concept of UAS operability, where the term 'operability' addresses
the safe and reliable functioning of the UAS as a system, the airworthiness of its
airborne sub-systems, and the safe and reliable functioning of its non-airborne subsystems
and functional payloads.
To ensure that the results of this study are aligned with typical aviation regulatory
systems, a regulatory basis was defined within which UAS operability guidelines
could be developed.
Based on the operability concept, and in the scope of the regulatory basis, a UAS
operability framework was developed for the UAS engineering domain. This
framework is an index and reference source from which appropriate operability
elements can be selected for a particular UAS. The scope of the framework is generic,
rather than UAS-type or -class specific, and includes operability elements for the UAS
as a system, for its airborne and non-airborne sub-systems, and for its payloads.
The framework was validated by developing lower hierarchical levels for the
framework and by populating each operability element of the framework with
appropriate engineering guidance criteria. The guidance criteria were derived and/or developed from industry 'best practices' found in the literature, or were newly
developed where no existing practices were found.
The significance of this study is found in its establishing of a generic UAS operability
framework that not only focuses on the airworthiness of the unmanned aircraft, but
addresses the operability of the UAS as a system, as well as the operability of its
airborne sub-systems, its non-airborne sub-systems and its payloads.
In practice, the UAS operability framework can be used in the UAS engineering
domain as an index and reference source to select relevant operability elements for a
particular UAS. The guidance criteria for the selected elements can subsequently be
used to develop the appropriate processes, procedures, requirements and
specifications to achieve initial operability of the UAS, and to maintain its continued
operability.
Although the objective of the research was achieved, the UAS operability framework
must still be applied and tested in real-life UAS projects and, where necessary, revised
to eliminate shortcomings and to provide for new and novel developments in UAS
engineering technologies. === AFRIKAANSE OPSOMMING: Die lugwaardigheidsertifisering van onbemande vliegtuigstelsels (OVS) word
normaalweg beskou as 'n reguleringsfunksie. In die afwesigheid van omvattende OVS
lugwaardigheidsregulasies bly die ontwikkeling van nuwe en unieke OVS, en die
inbedryfstelling daarvan in onafgesonderde lugruim, besonderse uitdagings vir beide
die OVS nywerheid en reguleerders. Die doelwit van hierdie navorsing was dus om
riglyne binne die bestek van die tipiese reguleringsregime te vestig wat deur die OVS
ingenieursdomein benut kan word om die veilige en betroubare funksionering van 'n
OVS te verseker, of dit gereguleer word aldan nie.
OVS lugwaardigheid word tans hoofsaaklik gebaseer op lugwaardigheidsvereistes vir
bemande vliegtuie. Die fokus is dan ook meerendeels op die onbemande vliegtuig en
die 'lugwaardigheid' van die afstandbeheerstasie. Die tipiese OVS bestaan egter uit
meer sub-stelsels en 'n weier beskouing van die 'lugwaardigheid' van 'n OVS is nodig.
Die konsep van OVS bedryfbaarheid is in hierdie studie ondersoek en voorgestel.
'Bedryfbaarheid' beteken in hierdie konteks die veilige en betroubare funksionering
van die OVS as 'n stelsel, die lugwaardigheid van die lug sub-stelsels, die veilige en
betroubare funksionering van die nie-lug sub-stelsels, asook die veilige en betroubare
funksionering van funksionele loonvragte.
Om te verseker dat die resultate van hierdie studie versoenbaar is met tipiese lugvaart
reguleringstelsels, is 'n reguleringsbasis omskryf vir die ontwikkeling van OVS
bedryfbaarheidsriglyne.
Gebaseer op die bedryfbaarheidskonsep, en binne die riglyne van die reguleringsbasis,
is 'n OVS bedryfbaarheidsraamwerk ontwikkel vir die OVS ingenieursdomein. Die
raamwerk is 'n indeks en verwysingsbron waaruit gepaste bedryfbaarheids-elemente
gekies kan word vir 'n bepaalde OVS. Die bestek van die raamwerk is generies en nie
beperk tot spesifieke OVS tipes of klasse nie. Die raamwerk sluit bedryfbaarheidselemente
in vir die OVS as stelsel, asook vir die lug en nie-lug sub-stelsels van die
OVS, en vir die loonvragte van die OVS. Die raamwerk se geldigheid was bevestig deur die struktuur van die raamwerk tot laer
vlakke uit te brei en gepaste ingenieursriglyne vir elke bedryfbaarheids-element in die
raamwerk te ontwikkel. Die riglyne was gebaseer op 'beste praktyke' soos beskryf in
die literatuur, of was van nuuts af ontwikkel waar geen bestaande praktyke gevind
kon word nie.
Die bydrae van hierdie studie is gesetel in die vestiging van 'n generiese OVS
bedryfbaarheidsraamwerk wat nie net gemik is op die lugwaardigheid van die
onbemande vliegtuig nie, maar wat die bedryfbaarheid in geheel van die OVS as
stelsel aanspreek, asook die bedryfbaarheid van die OVS se lug sub-stelsels, nie-lug
sub-stelsels en loonvragte.
In die praktyk kan die raamwerk in die OVS ingenieursdomein gebruik word om
gepaste bedryfbaarheids-elemente vir 'n OVS te kies. Daarna kan die
bedryfbaarheidsriglyne gebruik word om gepaste prosesse, prosedures, vereistes en
spesifikasies te ontwikkel om die OVS se aanvanklike en voortgesette bedryfbaarheid
te bewerkstellig.
Alhoewel die doelwit vir die navorsing bereik is, moet die OVS
bedryfbaarheidsraamwerk nog op werklike OVS projekte getoets word. Waar nodig,
moet die raamwerk dan hersien word om tekortkominge, asook nuwe en unieke
ontwikkelinge in OVS ingenieurstegnologie, aan te spreek.
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