Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Increasing air traffic and urbanisation has led to a cluttered airspace, particularly near
airports, where both complex terrain and multiple moving obstacles are frequent. Accurately
and efficiently predicting violations in safe separation criteria for commercial
aircraft, a process called conflict detection, is therefore crucial in assessing risk associated
with threats of collision. Existing avoidance systems in operation such as TCAS, EGPWS
and ATC exhibit shortcomings, leaving room for uncertainty and possible conflict scenarios.
A single on-board system capable of minimising errors in prediction would inform
conflict resolution decisions more accurately as well as support the notion of free flight, an
objective of next-generation air traffic management systems.
This thesis investigates the viability of a modern algorithm, probability flow, as a method of
probabilistic conflict detection for commercial aircraft in airport environments. Simulation
results for realistic flight scenarios are presented in comparison with a ground-truth result
obtained through Monte Carlo simulation. Observations are made regarding the suitability
of probability flow for real-world application. It is found that probability flow is capable
of calculating a tight upper bound to the probability of conflict quickly and accurately
for most conflict scenarios. However, unreasonably large overestimates on the probability
of conflict are obtained when flying parallel to an obstacle conflict region. This problem
could lead to a high frequency of false alerts, particularly in aborted landing scenarios
and at airports operating parallel runways. It is therefore advised that further research
be conducted to resolve this problem before probability flow can be reliably implemented
in an airport environment. / AFRIKAANSE OPSOMMING: Toenemende lugverkeer en verstedeliking het gelei tot ‘n deurmekaar lugruim, veral naby
lughawens, waar beide komplekse terrein en verskeie bewegende struikelblokke gereeld voorkom.
Akkuraat en doeltreffende voorspelling van oortredings in veilige skeidingskriteria
vir kommersiële vliegtuie, naamlik konflik opsporing, is dus van kardinale belang in die
beoordeling van die risiko wat verband hou met dreigemente van ‘n botsing. Bestaande vermyding
stelsels in werking soos TCAS, EGPWS en ATC toon tekortkominge, wat ruimte
laat vir onsekerheid en moontlike konflik scenario’s. ‘n Enkele aanboordstelsel, wat in
staat is om foute in voorspelling te verminder, sou konflikresolusie besluite meer akkuraat
in kennis stel, asook om die idee van vrye vlug te ondersteun, ‘n doelwit van toekomstige
lugverkeer beheerstelsels.
Hierdie tesis ondersoek die lewensvatbaarheid van ‘n moderne algoritme, waarskynlikheidsvloei,
as ‘n metode van probabilistiese konflik opsporing vir kommersiële vliegtuie in die
lughawens omgewing. Simulasie resultate vir realistiese vlug scenario’s word aangebied
in vergelyking met ‘n grond-waarheid resultaat wat verkry word deur middel van Monte
Carlo simulasie. Waarnemings word gemaak ten opsigte van die geskiktheid van waarskynlikheidsvloei
vir die werklikheid. Dit is bevind dat waarskynlikheidsvloei in staat is om die
berekening van ‘n stywe bogrens tot die waarskynlikheid van konflik vinnig en akkuraat
te bepaal vir die meeste konflik scenario’s. Tog is daar ‘n onredelike groot oorskatting
op die waarskynlikheid van konflik wat verkry word wanneer ‘n vliegtuig parallel met ‘n
hindernis konflik streek vlieg. Hierdie probleem kan lei tot ‘n hoë frekwensie van valse
waarskuwings, veral in mislukte landing scenario’s en by lughawens wat van parallel aanloopbane
gebruik maak. Dit word dus aanbeveel dat verdere navorsing gedoen word om
die probleem op te los voordat waarskynlikheidsvloei betroubaar in ’n lughawe omgewing
geïmplementeer word.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/97033 |
| Date | 03 1900 |
| Creators | Pienaar, Leanne Jane |
| Contributors | Jones, Thomas, 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 | 120 pages : illustrations |
| Rights | Stellenbosch University |
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