Thesis (MComm)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In a ground-based air defense (GBAD) military environment, defended assets on the ground require
protection from enemy aircraft entering the defended airspace. These aircraft are detected
by means of a network of sensors and protection is afforded by means of a pre-deployment of
various ground-based weapon systems. A fire control officer is responsible for deciding upon an
assignment of weapon systems to those aircraft classified as threats. The problem is therefore
to find the best set of weapon systems to assign to the threats, based on some pre-specified
criterion or set of criteria. This problem is known as the weapon assignment problem.
The conditions under which the fire control officer has to operate are typically extremely stressful.
A lack of time is a severely constraining factor, and the fire control officer has to propose
an assignment of weapon systems to threats based on his limited knowledge and intuition, with
little time for analysis and no room for error. To aid the fire control officer in this difficult
decision, a computerised threat evaluation and weapon assignment (TEWA) decision support
system is typically employed. In such a decision support system a threat evaluation subsystem
is responsible for classifying aircraft in the defended airspace as threats and prioritising
them with respect to elimination, whereas a weapon assignment subsystem is responsible for
proposing weapon assignments to engage these threats.
The aim in this thesis is to model the weapon assignment problem as a multiobjective decision
problem. A list of relevant objectives is extracted by means of feedback received from a weapon
assignment questionnaire which was completed by a number of military experts. By using two
of these objectives, namely the cost of assigning weapon systems and the accumulated single
shot hit probability, for illustrative purposes, a bi-objective weapon assignment model is derived
and solved by means of three multiobjective optimisation methodologies from the literature in
the context of a simulated, but realistic, GBAD scenario.
The analytic hierarchy process (AHP) is implemented by means of assessments carried out in
conjunction with a military expert. The assignment of weapon systems to threats is achieved
by means of a greedy assignment heuristic and an AHP assignment model. Both these methods
provide plausible results in the form of high quality assignments achieving an acceptable tradeoff
between the two decision objectives. However, a disadvantage of the AHP approach is that
it is inflexible in the sense that a large portion of its pre-assessments have to be reiterated if
the set of weapon systems and/or threats is adapted or updated.
A bi-objective additive utility function solution approach to the weapon assignment problem
is also developed as a result of various assessments having been carried out in conjunction
with a military expert. The assignment of weapon systems to threats is again achieved by
means of a greedy assignment heuristic and a utility assignment model. Both these methods
again provide high quality assignments of weapon systems to threats, achieving an acceptable
trade-off between the two decision objectives. However, a disadvantage of the utility function
approach is that if additional weapon systems are added to the current set of weapon systems, which achieve objective function values outside the current ranges of the values employed, new
utility functions have to be determined for the relevant objective function. Moreover, both the
AHP and utility function approaches are also constrained by generating only one solution at a
time.
A final solution approach considered is the implementation of a multiobjective evolutionary
metaheuristic, known as the Nondominated Sorting Genetic Algorithm II (NSGA II). This
approach provides very promising results with respect to high quality assignments of weapon
systems to threats. It is also flexible in the sense that additional weapon systems and threats
may be added to the current sets without the need of considerable additional computations or
significant model changes. A further advantage of this approach is that it is able to provide an
entire front of approximately pareto optimal solutions to the fire control officer. / AFRIKAANSE OPSOMMING: In ’n militêre grond-gebaseerde lugafweeromgewing vereis bates op die grond beskerming teen
vyandelike vliegtuie wat die beskermde lugruim binnedring. Hierdie vliegtuie word deur middel
van ’n netwerk van sensors waargeneem en deur middel van ’n ontplooing van ’n verskeidenheid
grond-gebaseerde wapenstelsels afgeweer. ’n Afvuur-beheer operateur is verantwoordelik vir die
besluit om wapenstelsels aan vliegtuie wat as bedreigings geklassifiseer is, toe te wys. Die
onderliggende probleem is dus om die beste stel wapens, volgens ’n voorafbepaalde kriterium
of ’n stel kriteria, aan die bedreigings toe te wys. Hierdie probleem staan as die wapentoewysingsprobleem
bekend.
Die toestande waaronder die afvuur-beheer operateur besluite ten opsigte van wapentoewysings
maak, is besonder stresvol. ’n Gebrek aan tyd is ’n uiters beperkende faktor, en die afvuurbeheer
operateur moet gevolglik binne ’n tydspan wat weinige analise en geen ruimte vir foute
toelaat, wapentoewysings volgens sy beperkte kennis en intuïsie maak. ’n Gerekenariseerde
bedreigingsafskatting-en-wapentoekenningstelsel kan gebruik word om die operateur met besluitsteun
te bedien. In sò ’n besluitsteunstelsel is ’n bedreigingsafskattingdeelstelsel verantwoordelik
om vliegtuie wat die beskermde lugruim binnedring as bedreigings of andersins te klassifiseer en
ten opsigte van eliminasie te prioritiseer, terwyl ’n wapentoewyingsdeelstelsel verantwoordelik is
om wapentoewysings aan die bedreigings voor te stel.
Die hoofdoel in hierdie tesis is om die wapentoewysingsprobleem as ’n multikriteria-besluitnemingsprobleem
te modelleer. ’n Lys van relevante doelwitte is met behulp van ’n wapentoewysingsvraelys
verkry wat aan militêre kenners vir voltooing uitgestuur is. Twee van hierdie
doelwitte, naamlik toewysingskoste en geakkumuleerde enkelskoot-trefwaarskynlikheid, is vir
illustratiewe doeleindes gebruik om ’n twee-doelwit wapentoewysingsprobleem te formuleer wat
met behulp van drie multikriteria-besluitnemingsmetodologië uit die literatuur in die konteks
van ’n realistiese, gesimuleerde grond-gebaseerde lugafweerscenario opgelos word.
Die analitiese hiërargiese proses (AHP) is met behulp van assesserings in samewerking met ’n
militêre kenner geïmplementeer. Die toewysing van wapenstelsels is met behulp van ’n gulsige
toewysingsheuristiek asook aan die hand van ’n AHP-toewysingsmodel bepaal. Beide hierdie
metodes is in staat om resultate van hoë gehalte te behaal wat ’n aanvaarbare afruiling tussen
die twee doelwitte verteenwoordig. ’n Nadeel van die AHP is egter dat dit onbuigsaam is in die
sin dat ’n groot hoeveelheid vooraf-assesserings herhaal moet word indien meer wapenstelsels
en/of bedreigings by die huidige sisteem gevoeg word.
’n Twee-doelwit additiewe nutsfunksiebenadering tot die wapentoewysingsprobleem is ook met
behulp van velerlei assesserings in samewerking met ’n militêre kenner ontwikkel. Die toewysings
is weereens met behulp van ’n gulsige wapentoewysingsheuristiek asook ’n nutstoewysingsmodel
bepaal. Beide hierdie metodes is ook in staat om resultate van hoë gehalte te behaal wat ’n
aanvaarbare afruiling tussen die twee doelwitte verteenwoordig. ’n Nadeel van die nutsfunksiebenadering
is egter dat indien addisionele wapenstelsels by die huidige stel wapenstelsels gevoeg word, en indien die waardes van hierdie addisionele wapenstelsels buite die grense van die doelfunksiewaardes
van die huidige wapenstelsels val, daar ’n nuwe nutsfunksie vir die relevante
doelwit van voor af bereken moet word. Beide die AHP- en die nutsfunksiebenaderings is
verder tot die lewering van slegs een oplossing op ’n slag beperk.
Laastens is ’n multikriteria evolusionêre metaheuristiek (die NSGA II) geïmplementeer wat ook
goeie resultate in terme van hoë-gehalte toewysings van wapenstelsels aan bedreigings lewer.
Die voordeel van hierdie benadering is dat dit buigsaam is in die sin dat die getal wapenstelsels
en bedreigings in die huidige sisteem aangepas kan word sonder om noemenswaardig meer
berekeninge of groot modelveranderinge teweeg te bring. ’n Verdere voordeel is dat die metaheuristiese
benadering daartoe in staat is om ’n front van benaderde pareto-optimale oplossings
gelyktydig te lewer.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/20007 |
| Date | 03 1900 |
| Creators | Lotter, Daniel Petrus |
| Contributors | Nieuwoudt, I., Van Vuuren, J. H., Stellenbosch University. Faculty of Economic and Management Sciences. Dept. of Logistics. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Format | 165 p. ; ill. |
| Rights | Stellenbosch University |
Page generated in 0.0027 seconds