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1. Introduction
A swarm or fleet of Unmanned Aerial Vehicles (UAVs) is a set of aerial robots i.e., drones that
work together to achieve a specific goal. Each drone in a swarm is propelled by a specific number of
rotors and can vertically hover, take off, and land (VTOL). The flight of the drones is controlled
either manually, i.e., by remote control operations, or autonomously by using processors deployed
on the drones. A common purpose for drones is a military one, but their civilian applications are
attracting increased attention in recent times. Indeed, low-cost drones and their swarms provide a
promising platform for innovative research projects and future commercial applications that will
help people in their work and everyday lives. Swarms of drones can be classified in different ways.
For example, Fig. 1 illustrates fully and partly (semi) autonomous swarms. From another point of
view, the classification can be envisioned in single-layered swarms with every drone being its leader
and multilayered swarms with dedicated leader drones at every layer, which reports to their leader
drones at a higher layer; a ground-based server station is the highest layer in this hierarchy. In each
swarm, every drone can have dedicated data collection and processing tasks with sufficient
computing capability to execute these tasks in real-time. Its central processing takes place on the
more performant server/base station or even in the cloud. The paper is aimed to (1) study the
characteristics of the drones and the swarm of drones, (2) discuss the existing technologies of linear
and model-based nonlinear controllers, and (3) assess the public awareness levels regarding drones
using an experimental query-based survey. To realize these contributions to the field of knowledge,
this paper is structured as follows. Section 2 follows this introduction in which drone application
fields are discussed. In Section 3, the classification of UAVs is presented. Section 4 lays out the
description of the dynamics and flying mechanisms of drones. Section 5 studies the key
characteristics of autonomous drone swarms.
Fig. 1. Classification of swarms.
The history of aviation has shown that the majority of aerial missions can be dull, dirty, or even
dangerous for humans, and thus, the deployment of Unmanned Aerial Vehicles (UAVs) can be an
advantageous solution with considerable benefits in terms of money and time (Tice, 1991).
Overall, there are numerous uses of UAVs that can involve various degrees of autonomy, and at
present, some notable examples include civilian (e.g., disaster relief, law enforcement),
commercial (e.g., cargo transportation, aerial surveillance), and military (e.g., reconnaissance,
attack) applications. According to the U.S. Department of transportation, the use of UAVs has in

2. the past decades experienced an increase, and nowadays, several missions can be performed much
safer and with less cost since there is no need for a pilot or a crew (Volpe, 2013). To no surprise,
this growth has created a competitive market with strict performance and delivery requirements,
and therefore, the aeronautical industry is currently faced with new challenges which in turn call
for a more efficient Product Development Process (PDP). Multidisciplinary Design Optimization
(MDO) is a method that can be used in the development of complex products to explore the design
tradeoffs through the concurrent analysis of several engineering disciplines. Like all active fields,
MDO has still a margin for improvement, and it can be argued that the computational efficiency
can often be a limitation towards its final implementation in the development process. In addition
to this, there are still several gaps in the modeling as well as the analysis capabilities, while a
further and rather a critical shortcoming is the lack of research on the integration of MDO in the
organizational functions. System of Systems (SoS) formulations are a higher level of modeling that
aims to bring forward new and improved capabilities that are beyond those of each system. A
typical SoS study includes an analysis of the design interactions with other products as well as the
environment, and it is in this capacity that it can be considered as a further dimension in the
development process. In general, the use of SoS is still in most applications at an experimental
stage, and to this date, the challenges towards a successful implementation can be found in the
model decomposition, the simulation of collaboration, and the computational efficiency of the
framework.
The Unmanned Aerial Vehicle (UAV) is a remotely piloted or self-piloted aircraft that can carry payloads
such as cameras, sensors, and communications equipment. All flight operations (including take-off and
landing) are performed without an onboard human pilot. In some reports of DOD, and Unmanned UAV
System (UAS) is preferred. In media reports, the term “drone” is utilized. The UAV mission is to perform
critical flight operations without risk to personnel and is more cost-effective than the comparable manned
system. A civilian UAV is designed to perform a particular mission at a lower cost or impact than a manned
aircraft equivalent. UAV design is essentially a branch of engineering design. Design is primarily an
analytical process that is usually accompanied by drawing/drafting. The design contains its own body of
knowledge that is independent of the science-based analysis tools that are usually coupled with it. Design is
a more advanced version of a problem-solving technique that many people use routinely. Research in
unmanned aerial vehicles (UAVs) has grown in interest over the past couple of decades. There has been a
tremendous emphasis on unmanned aerial vehicles, both fixed and rotary-wing types over the past decades.
Historically, UAVs were designed to maximize endurance and range, but demands for UAV designs have
changed in recent years. Applications span both civilian and military domains, the latter being the more
important at this stage. Early statements about performance, operation cost, and manufacturability are
highly desirable already early during the design process. Individual technical requirements have been
satisfied in various prototype, demonstrator, and initial production programs like Predator, Global Hawk,
and other international programs. The possible breakthrough of UAV technology requires support from the

3. aforementioned awareness of general UAV design requirements and their consequences on the cost,
operation, and performance of UAV systems.