Unmanned Aerial Vehicle Attitude Control Using L1 Adaptive Controller

L-1 adaptive controllers are proposed to control fixed-wing unmanned aerial vehicle attitude for both longitudinal and lateral motions simultaneously. A full-order nonlinear model of the aircraft, where actuator dynamics are considered, is used to design the proposed controllers. The different motion objectives of the aircraft are controlled via separate control loops. Based on the gap metric concept, two single-input single-output controllers are used for the longitudinal motion; and one multi-input multi-output for the lateral motion. For each loop, a suitable L-1 adaptive controller is designed, and the coupling between the loops is treated as a time-varying uncertainty. The full-order nonlinear model with the proposed controllers is used to evaluate the closed-loop performance by simulation. The simulation results show that the controllers ensure that the system outputs asymptotically track the outputs of an ideal system. The overall performance of the proposed controllers is drastically improved compared to that of standard PID controllers.