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Proefschrift
ter verkrijging van de graad van doctor
aan de Technische Universiteit Delft,
op gezag van de Rector Magnificus prof. dr. ir. J.T. Fokkema
voorzitter van het College voor Promoties,
in het openbaar te verdedigen op maandag 12 november 2007 om 15.00 uur
door
Fok BOLDERHEIJ
Master of Science (Cranfield University, UK)
Kapitein Luitenant ter Zee voor de Elektrotechnische Dienst der Koninklijke Marine
geboren te Vlaardingen
Dit proefschrift is goedgekeurd door de promotoren:
Prof. ir. dr.h.c. P. van Genderen
Prof. dr. ir. L.P. Ligthart
Samenstelling promotiecommissie:
Rector Magnificus, voorzitter
Prof. ir. dr.h.c. P. van Genderen, Technische Universiteit Delft, promotor
Prof. dr. ir. L.P. Ligthart, Technische Universiteit Delft, promotor
Prof. dr. ir. F.G.J. Absil, Nederlandse Defensie Academie
Prof. dr. ir. F.C.A. Groen Universiteit van Amsterdam
Prof. dr. ir. J.M. van Noortwijk Technische Universiteit Delft
Prof. drs. M. Boasson Universiteit van Amsterdam
Prof. dr. A. van Deursen Technische Universiteit Delft
Prof. dr. ir. F.G.J. Absil van het Koninklijk Instituut voor de Marine heeft als begeleider in
belangrijke mate aan de totstandkoming van het proefschrift bijgedragen.
ISBN 978-90-76928-13-5
Keywords: sensor management, situational awareness, threat assessment, risk estimation,
(Dynamic) Bayesian Networks.
The research described in this thesis was funded by the Netherlands Defence Academy and
the Centre for Automation of Mission Critical Systems (CAMS) – Force Vision.
Acknowledgements
Some people state that the execution of PhD research can be managed as a project. When
putting the finishing touch on this thesis, I draw the conclusion that this statement is incorrect.
From the experience I have gained with project management during my career, I recollect that
the art of project management involves the careful balancing of the elements time, finances
and quality and requires meticulous planning of the progress of a project. One of the most
important aspects of PhD research, innovation, cannot be planned however, as it requires
creativity and this human quality cannot be forced to manifest itself. It is possible to stimulate
creativity by organising brainstorm sessions or by exchanging ideas and opinions with experts
but when at the end of the day the starting piece of the jigsaw puzzle is not found, all that
remains is a heap of seemingly related but unconnected pieces. This is what happened to me:
after more than two years in which I spent half my time executing this research I had collected
a lot of ideas and topics that were somehow related to the problem area but still no clear
structure was visible. During a desperate search in a remote database I discovered the paper
a game theoretic approach to search by Harland Romberg that provided the required corner
piece of the puzzle. The ideas triggered by this paper enabled the construction of the
framework in which most of the already collected pieces fitted. Because creativity cannot be
planned and this is a fundamental concept in research, only the writing of the thesis can be
managed as a project but only after most of the research is finished.
I especially want to thank my first supervisor prof. ir. dr.h.c. Piet van Genderen and prof. dr.
ir. Frans Absil for supporting me during the first years of the research when I thought it was
adrift, for assisting me in keeping the research on the right course after I discovered the
navigational track and for helping me to detect and avoid submerged obstacles. Piet van
Genderen often approached the subject matter from unexpected angles, which invariably
resulted in very interesting discussions and topics that required further examination and
therefore these discussions were a valuable contribution to the final results. Frans Absil
always reviewed the results thoroughly and provided detailed comments that helped me to
improve the quality of the work. I want to thank my second supervisor prof. dr. ir. Leo
Ligthart for showing me how to shift the emphasis of the thesis from the problem that had to
be solved towards the innovative aspects of the research. I also want to express my gratitude
to prof. dr. ir. Jan van Noortwijk for showing me the shortcomings in the notation of the
Bayesian calculus and prof. drs. Maarten Boasson for discussing some design and
architectural issues.
This work started as a part of the STATOR (Sensor Timing And Tuning on Object Request)
research program on sensor management supported by Thales Naval Nederland, the Royal
Netherlands Naval College, and the International Research Center for Telecommunications
and Radar of the Delft University of Technology. I greatly appreciate the exchange of ideas
and discussions with the other project team members of whom I especially want to name dr.
ir. Hans Driessen, dr. ir. Yvo Boers, dr. ir. Maurice Houtsma, ir. Perry Verveld, ir. Jitze
Zwaga from Thales Naval Nederland and ir. Rene Thaens from the NATO C3 Agency.
In order to support this research, many interviews were made with staff of the Royal
Netherlands Navy. Their willingness to share their views on the Command and Control
process functions and operator roles is greatly appreciated
Because the execution of research was a part of my job description as lecturer above water
sensors and data communication at the Royal Netherlands Naval College, I thought the
V
STATOR project provided an excellent opportunity to satisfy these requirements. It turned
out however, that the combination of lecturing and research was not as straightforward as I
had anticipated. Because these tasks are only loosely correlated, much time is lost by
switching between them. I would therefore like to thank the (ex) staff of the Royal
Netherlands Naval College for their advice and support in executing these tasks and in
particular dr. Theo Hupkens and ir. Ben Bruggeman for helping me to combine the lecturing
and the research tasks, exchanging ideas and discussing the suitability of candidate
methodologies, dr.ir. Arthur Vermeulen and ir. Raymundo Hordijk for helping me with
mastering Matlab and Deborah Trimpe Burger (MA) for proof reading the manuscript.
About a year after the STATOR project was finished, I was posted to CAMS-Force Vision to
develop the sensor management concept further into an operational system. I want to thank
the management of CAMS-Force Vision for providing this opportunity and granting me time
for finishing the thesis. I also want to thank my colleagues and especially LTZE 2 OC ir.
Wilbert van Norden for his work on the scheduler and discussing new concepts.
And last but certainly not least, I would like to thank my wife Ans and my daughter Sanneke
for their patience and forbearance when I consumed valuable family time building the
prototype and writing this thesis. They only imposed the restriction that I was not allowed to
take the work with me on holidays (our notebook computer was only to be used for storing
photographs and searching the internet for the opening hours of family attractions).
Nevertheless, more than one planned weekend walk on the beach was lost by an incorrect
estimation of the time required to finish a subroutine, a section or a chapter. However, they
never really complained about this and were always there to support me when I needed them.
Fok Bolderheij
VI
Abstract
The management of sensors onboard of the vessels operated by the Royal Netherlands Navy
is becoming increasingly knowledge intensive due to the fact that these vessels are equipped
with state of the art sensor systems that provide more functionality and more accurate
information at the cost of more complex control mechanisms and due to the shift of
operational areas from the fairly stable environment of the Atlantic Ocean into littoral waters
with often dense civil traffic and rapidly changing geographical and meteorological
conditions. The shrinking defence budgets on the other hand drive a demand for crew
reduction, shorter education times and less training opportunities thus reducing the synergy
created within teams of operators and the knowledge and experience of individual operators.
This perception leads to the following problem definition: management of a set of complex
sensor systems under often rapidly changing environmental, operational conditions and
temporal constraints requires more skills and knowledge than is currently available. This
problem definition justifies the execution of research into the design of a sensor management
system that is capable of optimally controlling a set of complex sensor systems under rapidly
changing environmental conditions with respect to the mission objectives. The sensor
manager should also provide assistance in determining the optimal use of the sensors in the
planning stage of the mission.
From the problem definition, the functional requirements were gathered in the course of
which attention was also paid to the identification of the relevant non-functional (quality)
requirements to establish the starting point of the research.
The first step in the research concerned the analysis of the current sensor management
process and its position within the command and control process. It turned out that it was
completely operator-driven and that no clear guidelines existed. A literature survey yielded a
model of the command and control process and from it a high-level sensor control cycle based
on the Observe-Orient-Decide-Act loop could be constructed. This cycle uses information
gathered by sensors. This information is correlated, interpreted and used as the basis for
consequent (sensor management related) actions. From the survey, the command and control
processes that deliver the required sensor management information could be identified. The
survey however did not disclose generic sensor management principles and therefore in a
second step a series of interviews with operational experts was conducted. From these
interviews the conclusion was drawn that sensor management should support both the
complete and accurate (timely) compilation of a mission relevant picture of the man-made
and natural environment and the direction of appropriate actions (in a military context: the
weapon assignment and weapon direction processes). A novel approach introduced in this
research was the modelling of this environment as a set of objects that could potentially
endanger the mission objectives. This approach enabled the description of the search for
completeness as the pursuit of a one-to-one relationship between each relevant (with respect
to the mission) element of the environment and its object representation within the picture of
the environment that is compiled by the Command and Control process. The accuracy of this
picture is modelled by means of the uncertainty related to the relevant properties (or attributes
as they are called in the object-oriented terminology) of each object.
To initiate the sensor control cycle, virtual or expected objects were introduced to model
intelligence information or other prior knowledge. Objects observed by the deployed sensors
consequently complement this set of objects.
VII
The perception that the picture of the environment is composed of objects instigated an
object-oriented design approach resulting in the development of a three-stage sensor manager
concept.
The first stage of the sensor manager reviews the uncertainty connected with each attribute of
an object in the compiled picture and determines what task(s) should be executed to reduce
this uncertainty.
The second stage of the sensor manager selects the most appropriate sensor for this task from
the set of available sensors based on the quality of information provided by each sensor.
The third stage of the sensor manager determines the sensor settings for the particular task
output by the second stage and hands tasks back to the second stage if the sensor has
insufficient resources to execute all tasks. The second stage then assigns these tasks to a less
appropriate sensor.
It is clear that the process of returning tasks to the second stage of the sensor manager should
start with the least important task and therefore a prioritising mechanism was required. When
existing prioritising mechanisms were reviewed, it appeared that they could only be used in
relation to objects that were already detected and that these mechanisms could not be utilised
to allocate surveillance functions to search for the expected objects in order to ensure the
completeness of the compiled picture. Hence a new type of prioritising mechanism was
developed that is capable of estimating the risk of both the expected but undetected objects
and the already detected objects. This mechanism determines the costs of the damaging event
caused by the object, being its lethality and the probability of occurrence of this event. To
estimate this probability of occurrence, an event tree was constructed that was based on the
state diagram of a missile system and those events that lead to a state transition. This event
tree was consequently converted into a Dynamic Bayesian Network that estimates the
probability of being hit by this missile from the underlying events.
Using this novel prioritising concept, the high-level design of the sensor manager embedded
in a basic object-oriented combat management system featuring those processes that deliver
the required sensor management related information could be completed. From this design a
prototype was constructed that was tested in a simulated environment using a scenario that
was drafted with the aid of operational experts. In this simulation the management of a Multi-
Function Radar was tested as this type of sensor is renowned for its difficult deployment. It
was assessed that a sensor manager capable of handling this type of sensors can be expanded
without too many problems into a multi sensor management system by making more
resources and functions available.
The execution of this scenario showed that it was possible to deploy the multi-function radar
completely autonomously by utilising prior information and from this result it can be deduced
that mission-driven, autonomous sensor management is feasible. The prototype also provides
the possibility to integrate radar performance prediction tools that predicts the sensor
performance for the prevailing meteorological and environmental conditions thus effectively
addressing the identified problem.
The generic sensor management principles that were postulated do not restrict the sensor suite
to being located at a single platform and therefore a sensor manager that is developed along
these principles is theoretically capable of handling a suite of distributed sensors. The
research showed that the management principles could also be used to manage other resources
and the sensor manager may well be expanded into a resource manager.
VIII
Because the developed sensor manager was intended to be a proof-of-concept, a lot of issues
like the integration with existing combat management systems and the interfacing with
different sensor systems still need to be addressed before the sensor manager can become
fully operational.
IX
X
Description:h.c. Piet van Genderen and prof. dr. ir. Frans Absil for supporting me during the first years of the research when I thought it was adrift, for assisting me in keeping the research on the right course after I discovered the navigational track and for helping me to detect and avoid submerged obstacl
