Hierarchical Control of Fully-Actuated Hexarotors: Architecture Revision and Physics-Based Validation

Nowadays, the use of aerial robots, such as multi-rotor UAVs (Unmanned Aerial Vehicles), is becoming increasingly widespread across various applications, including exploration, surveillance, monitoring, and more. For this reason, new optimal control strategies for such platforms are being actively researched. The objective of this thesis is to improve a nonlinear control solution, known as Hierarchical Control, for fully-actuated hexarotors, which are multi-rotor UAVs equipped with six propellers arranged in such a way as to achieve a fully-actuated platform, thus enabling control over all six degrees of freedom of a rigid body in three-dimensional space. Specifically, the work aims to describe the operating principles of the Hierarchical Controller, improve its existing architecture, and present a revised version that addresses current shortcomings and introduces structural enhancements. Subsequently, to assess the performance of the improved Hierarchical Controller architecture and to carry out an objective comparison, two other state-of-the-art control strategies will be introduced, and several numerical simulations will be performed in MATLAB/Simulink. In particular, numerical simulations in MATLAB/Simulink were carried out to evaluate the performance difference between the improved Hierarchical Controller and its original version. Afterwards, the improved Hierarchical Controller is compared with the other state-of-the-art control strategies under ideal conditions, in the presence of sensor noise, and during a representative real-world tracking task. This thesis work concludes with a physics-based simulation in Gazebo, which confirms the results obtained through numerical validation by comparing the performance of the proposed controller with that of an alternative control strategy along a predefined trajectory.