Robust Backstepping Control of a Quadrotor Unmanned Aerial Vehicle under Colored Noises

Advances in software and hardware technologies have facilitated the production of quadrotor unmanned aerial vehicles (UAVs). Nowadays, people actively use quadrotor UAVs in essential missions such as search and rescue, counter-terrorism, firefighting, surveillance, and cargo transportation. While performing these tasks, quadrotors must operate in noisy environments. Therefore, a robust controller design that can control the altitude and attitude of the quadrotor in noisy environments is of great importance. Many researchers have focused only on white Gaussian noise in their studies, whereas researchers need to consider the effects of all colored noises during the operation of the quadrotor. This study aims to design a robust controller that is resistant to all colored noises. Firstly, a nonlinear quadrotor model was created with MATLAB. Then, a backstepping controller resistant to colored noises was designed. The designed backstepping controller was tested under Gaussian white, pink, brown, blue, and purple noises. PID and Lyapunov-based controller designs were also carried out, and their time responses (rise time, overshoot, settling time) were compared with those of the backstepping controller. In the simulations, time was in seconds, altitude was in meters, and roll, pitch, and yaw references were in radians. Rise and settling time values were in seconds, and overshoot value was in percent. When the obtained values are examined, simulations prove that the proposed backstepping controller has the least overshoot and the shortest settling time under all noise types.