Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In recent years the aviation industry has shown an interest in the airborne refuelling
of large transport aircraft to enable increased payload mass at take-off and
to extend aircraft range. Due to the large volume of fuel to be transferred, a boom
and receptacle refuelling system with a larger fuel transfer rate is employed. The
refuelling operation is particularly difficult and strenuous for the pilot of the receiver
aircraft, because the position of the receptacle relative to the tanker aircraft must
be maintained within a narrow window for a relatively long period of time. The
airborne refuelling of a large aircraft is typically much more difficult than that of a
fighter aircraft, since the large aircraft is more sluggish, takes much longer to refuel,
and has a relatively large distance between its refuelling receptacle and its centre of
mass. These difficulties provide the motivation for developing flight control laws for
Autonomous In-Flight Refuelling (AIFR) to alleviate the workload on the pilot.
The objective of the research is to design a flight control system that can regulate
the receptacle of a receiver aircraft to remain within the boom envelope of a tanker
aircraft in light and medium turbulence. The flight control system must be robust
to uncertainties in the aircraft dynamic model, and must obey actuator deflection
and slew rate limits.
Literature on AIFR shows a wide range of approaches, including Linear Quadratic
Regulator (LQR), μ-synthesis and neural-network based adaptive control, none of
which explicitly includes constraints on actuator amplitudes, actuator rates and
regulation errors in the design/synthesis. A new approach to designing AIFR flight
control laws is proposed, based on Linear Matrix Inequality (LMI) optimisation.
The relatively new LMI technique enables optimised regulation of stochastic systems
subject to time-varying uncertainties and coloured noise disturbance, while simultaneously
constraining transient behaviour and multiple outputs and actuators to
operate within their amplitude, saturation and slew rate limits. These constraints
are achieved by directly formulating them as inequalities. / AFRIKAANSE OPSOMMING: Die lugvaart industrie toon huidiglik ’n belangstelling in die brandstof oordrag
tussen twee groot vervoervliegtuie gedurende vlug, met die doel om die maksimum
opstyggewig kapasiteit sowel as die maksimum ononderbroke vlugafstand vermoë
van die hervulde vliegtuig te vermeerder. ’n Boom hervulling-stelsel word geïmplementeer
om die hoë spoed van brandstof oordrag te voorsien. Die verrigting van
vluggebonde hervulling van ’n groot, trae vliegtuig is moeiliker en meer veeleisend
as bv. van ’n vegvliegtuig, veral vir die vlieënier van die hervulde vliegtuig, wat
sy boom-skakel moet reguleer binne ’n relatiewe klein boom bewegingsruimte vir ’n
relatiewe lang tydperk. Die kinematika betrokke speel ook ’n groter rol in ’n groot
hervulde vliegtuig a.g.v. die langer afstand tussen die boom-skakel en die massa middelpunt/
draaipunt. Hierdie bied die motivering om ’n beheerstelsel te ontwikkel wat
die taak outomaties uitvoer.
Die doel van die navorsing is om ’n beheerstelsel te ontwerp wat die boom-skakel
van die hervulde vliegtuig outomaties reguleer binne die bewegingsruimte van die
boom, gedurende ligte en matige turbulensie. Daar word van die beheerder vereis
om robuust te wees teen onsekerhede in die vliegtuig se meganika, sowel as om die
beheer oppervlaktes en turbines van die vliegtuig binne hul defleksie-, wringkrag- en
sleurtempo-perke te hou.
Daar bestaan reeds ’n groot verskeidenheid van benaderings tot die outomatisering
van luggebonde hervulling, onder andere LQR, μ-sintese en neurale-netwerk
gebaseerde aanpasbare beheer, waarvan geeneen perke op aktueerders en regulasie
foute direk in die ontwerp insluit nie. ’n Nuwe benadering word voorgestel wat
gebaseer is op Linear Matrix Inequality (LMI) optimering. Die LMI tegniek is relatief
nuut in die gebruik van beheerstelsel ontwerp. Dit stel die ontwerper in staat
om ’n stogastiese stelsel, onderworpe aan tydvariante-stelsel-variasie en gekleurde
ruis versteurings, optimaal te reguleer, terwyl aktueerders en stelsel gedrag direk
beperk word.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/80195 |
| Date | 03 1900 |
| Creators | Claase, Etienne H. |
| Contributors | Engelbrecht, J. A. A., Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 282 p. : ill. |
| Rights | Stellenbosch University |
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