Damaged aircraft control using a QFT designed flight controller

A controlled plant´s dynamics can very significantly if the operating points change. This presents problems for flight control system synthesis procedures based on pointwise designs, as aircraft dynamics vary widely within the flight envelope. This paper addresses flight control system synthesis and the accommodation of controlled plant variation in its design envelope by using the frequency domain based quantitative feedback theory multiple-input multiple-output robust control system design method. Plant variations considered include varying flight conditions in the flight envelope and damage to aerodynamic control surfaces. The aircraft used in the design is an unmanned research vehicle owned by the United States Air Force Wright Laboratory. Digital flight controllers for the aircraft´s longitudinal and lateral channels and an outer-loop autopilot are designed and validated with simulations containing nonlinear saturation elements