A Comparative Study of Different Control Structures for Flight Control with New Results

Abstract

This paper presents several different control structures that facilitate flight control and does a comparison between them. Specifically, this paper considers command-filtered backstepping, nonlinear dynamic inversion (NDI), and a new decoupled approach that decouples the rotational and translational dynamics by estimating the higher order derivatives of the angle of attack and sideslip angle. The latter is also augmented by exploiting a feedback of the control deficiency resulting in improved performance. A series of simulations is performed to gage the performance of different controllers, showing the performance in the case of sensor noise, when performing aggressive maneuvers, when exposed to wind disturbances, as well as when there are model imperfections. The main finding is that all control structures work well for flight control, but the new decoupled method is able to improve the performance. A major reason for the improvement is that the decoupling method alleviates the tuning of the control gains, thus allowing for faster response through suitable gains.