Differential flatness and fault detection in flight guidance dynamics

Abstract

Differential flatness, a property of some dynamic systems, introduced from the theory of differential geometry, has made possible the development of new tools to control and diagnose complex nonlinear systems. In the aerospace field, some authors have considered the differential flatness of the dynamics of vertical-takeoff-and-landing (VTOL) vehicles, others have considered the differential flatness of relative and formation flight dynamics for different types of flying devices. In this chapter, flight guidance dynamics are shown to be implicit differentially flat with respect to the inertial position of an aircraft. This proves the existence of a set of relations between these flat outputs and the state variables representative of flight guidance dynamics and between these flat outputs and the basic inputs to flight guidance dynamics. A neural network is introduced to obtain, from the actual trajectory, nominal flight parameters that can be compared with actual values to detect abnormal behavior.