Study of controllers for a Quadrotor Uav

Abstract

Quadrotor Unmanned Aerial Vehicles (UAVs) have become vital tools in fields such as surveillance, search-and-rescue, and environmental monitoring due to their flexibility and precise maneuvering capabilities. However, managing the complex and inherently unstable dynamics of quadrotors remains a challenge, requiring effective control systems. This thesis work presents a detailed mathematical model for a Vertical Take-off and Landing (VTOL) type Unmanned Aerial Vehicle (UAV) known as the quadrotor. The nonlinear dynamic model of the quadrotor is formulated using the Newton-Euler method, the formulated model is detailed including aerodynamic effects and rotor dynamics that are omitted in many literature. The motion of the quadrotor can be divided into two subsystems; a rotational subsystem (attitude) and a translational subsystem (altitude and x and y motion). Although the quadrotor is a 6 DOF underactuated system, the derived rotational subsystem is fully actuated, while the translational subsystem is underactuated. The derivation of the mathematical model is followed by the development of four control approaches to control the altitude, roll, pitch and yaw of the quadrotor in space. The first approach is based on the linear Proportional-Derivative (PD) controller. The second control approach is based on the nonlinear Sliding Mode Controller (SMC). The parameters and gains of the forementioned controllers were tuned manually in MATLAB/Simulink in order to track the set point smoothly. Simulation based experiments were conducted to evaluate and compare the performance of the two developed control techniques in terms of dynamic performance and stability.