Backstepping-Based Flight Control with Adaptive Function Approximation

TLDR

The paper proposes a command‑filtered backstepping controller that employs adaptive function approximation for UAV flight control. The controller is built with three nested feedback loops that process command inputs for airspeed, flight‑path angle, and wind‑axis, generating bounded rate and surface position commands while keeping the sideslip angle zero. The method guarantees Lyapunov stability of the adaptive function approximation despite magnitude, rate, and bandwidth constraints on intermediate states and control surfaces.

Abstract

A command filtered backstepping approach is presented that uses adaptive function approximation to control unmanned air vehicles. The controller is designed using three feedback loops. The command inputs to the airspeed and flight-path angle controller are x c , γ c , V c and the bounded first derivatives of these signals. That loop generates comand inputs μ c , α c for a wind-axis angle loop. The sideslip angle command β c is always zero. The wind-axis angle loop generates rate commands P c , Q c , R c for an inner loop that generates surface position commands. The control approach includes adaptive approximation of the aerodynamic force and moment coefficient functions. The approach maintains the stability (in the sense of Lyapunov) of the adaptive function approximation process in the presence of magnitude, rate, and bandwidth limitations on the intermediate states and the surfaces.