Combining Homogeneous High Order Sliding Mode and Nonlinear Dynamic Inversion for fixed wing aircraft attitude and speed control

Abstract

Abstract This paper addresses the problem of robust flight control for fixed wing aircrafts. Such systems are generally of Multi-Input Multi-Output (MIMO) form, tightly coupled and highly nonlinear whereby the nonlinearity resides both in the dynamic equations and in the aerodynamic coefficients. Consequently, we propose to combine Homogeneous High Order Sliding Mode (HHOSM) and Nonlinear Dynamic Inversion (NDI) approaches in order to deal with the piloting controller. The overall controller is designed so as to ensure the tracking of desired longitudinal velocity and attitude angles. The dynamics inversion uses nonlinear full-state feedback to globally linearize the dynamics of the selected controlled variables so that a linear controller can then be applied to regulate these variables with a desirable closed-loop behavior. To handle the nonlinearity, the desired closed-loop dynamics are given by an HHOSM controller. Simulations are carried out on a real-time virtual simulation platform for the development of Aircraft Control Systems (ACS). The obtained results demonstrate the effectiveness of the proposed controller. It is shown that HHOSM-NDI autopilot delivers a high dynamic tracking performance and can alleviate the chattering effect. Moreover, finite time convergence to the origin is ensured.