|dc.description.abstract||The quadrotor is a type of unmanned aerial vehicles (UAVs) which is gaining popularity
over the past few years for its potential applications. Quadrotor UAVs are used, for instance,
for surveillance, search and rescue missions, monuments inspection, and aerial photography.
The crucial step towards a reliable application is the development of efficient attitude estimation
and control algorithms. The primary focus of this thesis consists in investigating
various attitude control techniques and their applications.
A nonlinear attitude estimator and a PD-like controller have been successfully implemented
on a Quadrotor UAV. However, the stability proof of the attitude observer/controller combination
is not obvious as the system is nonlinear. To solve this problem, an attitude
controller directly relying on inertial vector measurements and angular velocity has been
proposed. Some practical methods such as filtering and vector decoupling were developed
and discussed. Moreover, an inertial measurements based velocity-free attitude controller
has been designed.
Finally, real-time implementation has been conducted on a small-scale low-cost quadrotor
UAV. Experimental results have been carried out to show the effectiveness of the proposed
controllers and some experimental problems and further approaches of the velocity-free
controller are discussed.||en_US