Minimal Order Disturbance Estimator Design for Aircraft Load Alleviation Control

Abstract

In this paper a novel approach to design linear disturbance estimators is presented. The model based design approach relies on advanced nullspace computation techniques to derive estimators which decouple everything but the disturbance input from the estimation signal. The main advantage of the approach is that disturbance estimators of minimal order can be designed. To facilitate the low order estimator design also for problems of very high order, an advanced model approximation technique, which allows to efficiently reduce the design model state dimension, is discussed. The presented approaches are applied to a generic model of a business jet aircraft. The derived disturbance estimator is used in a control algorithm to reduce the wing bending moments on the aircraft in case of wind gusts. Both, the disturbance estimator together and the load alleviation controller are verified in a non-linear closed loop aircraft simulation model.