Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The air-to-air refuelling of large aircraft presents challenges such as a long fuel transfer
time, slow aircraft responses and a large distance between the aircraft CG and the
receptacle position. This project addresses some of these issues by adding a control
system to keep the receiver aircraft in the correct position relative to the tanker to
enable fuel transfer.
This project investigates different control strategies which are designed to control the
A330-300 during refuelling at one trim condition. The controllers are based on a mathematical
aircraft model which was derived from a simulation model received from
Airbus.
The first set of controllers uses the aircraft actuators directly. Controllers that are
based on the CG dynamics and the receptacle dynamics are compared. Due to the large
distance between the CG and the receptacle it was found to be essential to control the
receptacle position, and not only the CG position. Also, a controller that is based on a
model of the receptacle dynamics performs better.
The second set of controllers uses the aircraft manual control laws as an inner loop
controller. This set of controllers and the last direct actuator controller use the same
axial controller that uses the engine thrust to control axial position.
It was found that both the direct actuator controller and the manual control laws
controller are able to keep the receptacle within the disconnect envelope in moderate
turbulence. In both sets of controllers the axial controller fails to keep the receptacle
reliably within the disconnect envelope in light turbulence.
From the results it is concluded that both the direct actuator control and manual control
laws can be used to successfully control the receptacle position in the normal and lateral
positions as long as the receptacle kinematics are included in the control design. Using
only the engine thrust for axial control is insufficient. Several recommendations are
made to improve the axial control and also how these results can be used in future
work. / AFRIKAANSE OPSOMMING: Die lug-tot-lug brandstof hervulling van groot vliegtuie het uitdagings soos ’n lang
hervullingstyd, stadige vliegtuig dinamika en ’n groot afstand tussen die hervullingspoort
en die vliegtuig massamiddelpunt. Hierdie projek spreek sommige van hierdie
uitdagings aan deur ’n beheerstelsel by te voeg wat die vliegtuig in die korrekte posisie
relatief tot die tenker hou vir brandstofoordrag om plaas te vind.
Hierdie projek ondersoek verskillende beheerstrategieë wat ontwerp is om die A330-
300 te beheer by ’n enkele gestadigde toestand. Die beheerders is gebaseer op ’n
wiskundige vliegtuigmodel wat vanaf ’n simulasiemodel afgelei is. Die simulasiemodel
is vanaf Airbus verkry.
Die eerste stel beheerders beheer direk die vliegtuig se beheeroppervlakke. Beheerders
wat onderskeidelik die massamiddelpunt en die hervullingspoort beheer word vergelyk.
Daar is gevind dat dit essensieel is om die hervullingspoort te beheer en nie slegs die
massamiddelpunt nie, as gevolg van die groot afstand tussen hierdie twee punte.
Die tweede stel beheerders gebruik die vliegtuig se eie beheerwette as ’n binnelusbeheerder
en vorm self die buitelus. Albei stelle beheerders gebruik dieselfde aksiale
beheerder wat enjin stukrag gebruik om die aksiale posisie te beheer.
Daar is gevind dat beide stelle beheerders die hervullingspoort binne die ontkoppelingsbestek
kan hou in die normale en laterale rigtings tydens matige turbulensie. In beide
stelle beheerders is dit die aksiale beheerder wat faal om die hervullingspoort betroubaar
in posisie te hou, selfs in ligte turbulensie.
Vanaf die resultate word afgelei dat beide die direkte beheerder en die buitelusbeheerder
gepas is om die laterale en normale posisiebeheer toe te pas mits die dinamika
van die hervullingspoort in ag geneem word. Om slegs stukrag te gebruik vir aksiale
beheer is nie voldoende nie, en verskeie voorstelle word gemaak om die aksiale beheer
te verbeter in toekomstige navorsing.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/20239 |
| Date | 03 1900 |
| Creators | Venter, Jeanne Marie |
| 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 | 107 p. : ill. |
| Rights | Stellenbosch University |
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