Simple Adaptive Delta Operator Aircraft Flight Control for Accommodation of Loss of Control Effectiveness

Abstract

A new proof for stability of delta operator simple adaptive control is presented in terms of a set of Linear Matrix Inequalities (LMIs). The paper shows how to design a feedforward gain to satisfy the LMIs over a polytope of loss of control effectiveness failures. The MATLAB Robust Control Toolbox is used to find the feedforward gain with the smallest norm that satisfies the LMIs. Examples are presented of the F/A-18 aircraft and the Innovative Control Effectors (ICE) tailless aircraft that show the design of a feedforward gain for a loss of control effectiveness in any one control effector. The designs use a fixed eigenstructure assignment controller for an inner loop augmented with the simple adaptive controller. Simulations of both aircraft include simultaneous loss of control effectiveness failure and lateral wind gust. Simulation results for the F/A-18 aircraft show that the adaptive controller achieves almost perfect tracking whereas the nonadaptive controller cannot achieve a coordinated turn when an aileron failure occurs. The ICE tailless aircraft uses sideslip, washed-out stability axis yaw rate, and stability axis roll rate feedback for both the inner loop eigenstructure assignment controller and the simple adaptive controller. However, the adaptive controller also uses bank angle feedback. Simulation results for the ICE tailless aircraft show that the adaptive controller achieves almost perfect tracking whereas the nonadaptive controller diverges when an all moving tip failure occurs.