Design of H-infinity controller for VTOL tiltrotor unmanned aerial vehicle

This paper presents an optimized robust H-infinity controller for Vertical Take-off and Landing (VTOL) tiltrotor Unmanned Aerial Vehicle (UAV). UAVs play a significant contribution in various applications, including rescue teams, border patrol, police and inspection of buildings, pipelines, coasts, and terrains. A tri tiltrotor UAV is a combines the features of both fixed-wing and rotorcrafts. It has the advantage of both the cruise speed of a fixed-wing and VTOL ability of a rotary-wing. The two front rotors tilt the vehicles from the vertical flight to horizontal and vice versa. Another rotor positioned in the middle is behind the centreline of the fuselage with a lesser angle for lift augmentation. The model of the tri tiltrotor UAV is derived mathematically using Newton-Euler formulation and simulated in MATLAB/SIMULINK. The aerial vehicle is inherently dynamically unstable. The proposed H-infinity controller considers the stability and performance problem of UAV under external wind and aerodynamic disturbances. The simulation results depicts that the designed controller attains robust performance and stability, and acceptable adaptability in the presence of uncertainties during all three flight modes.