Direct Adaptive Backstepping Flight Control for Quadcopter Trajectory Tracking

In the near future, unmanned aerial vehicles, are probably going to be integrated in the airspace and the current air traffic management concepts, need to be reviewed. Enhancements are expected from reliability, safety, and accuracy point of view. Adaptive flight control could support partially such challenge, regarding its capability to face modelling inaccuracies, parameter uncertainties and external disturbances. In addition, it could improve both of the flying and handling qualities, and impacts positively stability and maneuvrability margins, especially in the presence of unfavorable flight conditions. The main objective of this paper deals with a quadcopter adaptive flight control system that generates the necessary control laws to perform accurately, as well as possible, the reference flight trajectories. In this paper, a direct dynamical adaptive flight controller, based on backstepping approach, is developed for quadcopter trajectory tracking, where minimum phase and observability conditions are checked from differential geometry point of view. Developed direct adaptive backstepping flight control system provides nonlinear adaptive control laws in an iterative and systematic procedure design. Therefore, interlaced tuning functions are used to estimate and update laws in order to compensate the uncertain parameters of interest. The global stability of the proposed adaptive flight control system is guaranteed, based on Lyapunov theory, where the design of adaptation laws according to some quadcopter parameters is developed. Numerical simulations are performed for the quadcopter, engaged in complex trajectory tracking, and obtained results show the feasibility and effectiveness of the proposed adaptive flight control approach.