Robust control of aircraft flight in conditions of disturbances

Abstract

One of the most dangerous parts of the flight is the landing phase, as most accidents occur at this stage. In order to reduce the effect of the low-level wind shear on the longitudinal motion of the aircraft in the glide path landing mode (task) a robust H- control is proposed. Dynamic models of the plane and wind shear are built. H<sub>2</sub> and H<sub>∞</sub> synthesis methods are investigated for the task of aircraft flight control in a vertical plane during landing under conditions of undefined disturbances. Both control methods allow to reduce height deviation significantly. However, suboptimal control H<sub>∞</sub> provides better quality of transition processes both in height and speed than optimal control H<sub>2</sub>. The results of simulation of the synthesized system confirm the effectiveness of H<sub>∞</sub> - control for increasing robust stability to uncertainties caused by wind disturbances.

Mixed H₂/H_∞ robust controllers in aircraft control problem

“…This research is devoted to the analysis of a particular aircraft glide path trajectory, characterized by a linear trajectory with a defined flight path angle 𝜃 𝑔𝑙 (𝜃 𝑔𝑙 = 2.7 degrees) in height and range coordinates [31], [36]. The main purpose of synthesized system is to maintain a consistent airspeed 𝑉 0 = 71.375 m/s and a predetermined height ℎ = 400 m under the influence of wind disturbances, when moving on a glide path.…”

“…The main purpose of synthesized system is to maintain a consistent airspeed 𝑉 0 = 71.375 m/s and a predetermined height ℎ = 400 m under the influence of wind disturbances, when moving on a glide path. The model is presented in [31]. Studies have found that the output signal energy is minimized when a stochastic perturbation model in the form of white noise is served as an input in H2 theory.…”

“…Two crucial control variables of an aircraft, namely engine thrust force 𝑇 and angle of attack 𝛼, are contingent upon the deflection of throttle and elevator, respectively. The equations of flight dynamics for an aircraft in the vertical dimension, influenced by wind disruption in projection on the coordinate axes, are defined by a system of nonlinear differential equations [31], [38]: (…”

“…As a result, the non-linear aircraft model is transformed into a system of linear differential equations in increments. The matrix representation of linear system takes the form (1), where key vectors: 𝑥 = (∆𝑉, ∆𝜃, ∆𝜔 𝑧 , ∆𝜗, ∆ℎ, ∆𝑇) 𝑇 represents the state, 𝑤 = (𝑤 𝑌 , 𝑤̇𝑋, 𝑤̇𝑌) 𝑇 -wind disturbance, 𝑢 = (∆𝜗 су , ∆𝛿 𝑡 ) 𝑇control [31], [36].…”

“…Karimtaevna and Asylbekkyzy [30] outlines a design methodology and implementation of robust control using H∞ synthesis tools, which allows to cope more effectively with parameters and load perturbation. The research conducted in Karimtaevna et al [31] delves into a meticulous investigation of the H2 and H∞ synthesis methods, specifically exploring their potential in the realization systems responsible for controlling the flight of an aircraft during the crucial landing phase, while effectively mitigating the impact of external disturbances.…”