  Unmanned aerial vehicles (UAVs) have become very popular for many military
and civilian applications including in agriculture, construction, mining,
environmental monitoring, etc. A desirable feature for UAVs is the ability to
navigate and perform tasks autonomously with least human interaction. This is a
very challenging problem due to several factors such as the high complexity of
UAV applications, operation in harsh environments, limited payload and onboard
computing power and highly nonlinear dynamics. The work presented in this
report contributes towards the state-of-the-art in UAV control for safe
autonomous navigation and motion coordination of multi-UAV systems. The first
part of this report deals with single-UAV systems. The complex problem of
three-dimensional (3D) collision-free navigation in unknown/dynamic
environments is addressed. To that end, advanced 3D reactive control strategies
are developed adopting the sense-and-avoid paradigm to produce quick reactions
around obstacles. A special case of navigation in 3D unknown confined
environments (i.e. tunnel-like) is also addressed. General 3D kinematic models
are considered in the design which makes these methods applicable to different
UAV types in addition to underwater vehicles. Moreover, different
implementation methods for these strategies with quadrotor-type UAVs are also
investigated considering UAV dynamics in the control design. Practical
experiments and simulations were carried out to analyze the performance of the
developed methods. The second part of this report addresses safe navigation for
multi-UAV systems. Distributed motion coordination methods of multi-UAV systems
for flocking and 3D area coverage are developed. These methods offer good
computational cost for large-scale systems. Simulations were performed to
verify the performance of these methods considering systems with different
sizes.
