Development of a robust control technique on failures of the xcg measurement sensor

Abstract

The inner-loop flight control law is designed to satisfy the flying quality requirements, which include the change of XCG (longitudinal Center of Gravity) position due to fuel consumption, payload drop and/or failure occurrence in major subsystems such as the fuel system while operating in the overall flight envelope. Therefore, to make the aircraft have wide XCG travel in flight operation, the flying qualities and maneuvering performance can be improved by designing the flying quality parameters using additional information such as the weight and XCG position to the inner-loop control law. However, this design approach can seriously deteriorate the stability of the aircraft in the event of fuel mismanagement or a sensor failure for the XCG. An additional design technique should be considered to ensure the flight safety in response to various abnormal situations. This paper proposes a reconfiguration control technique based on the Nonlinear Dynamic Inversion (NDI) control to guarantee flight safety in case of XCG sensor failure and information uncertainties that the aircraft has wide XCG travel in flight operation. The performances of the proposed control method are evaluated by the frequency-domain linear analysis and time-domain numerical simulations using the advanced trainer model. The evaluation result confirms that the proposed control method satisfies the level of required flying qualities and ensures flight safety in the event of sensor failure for the XCG measurement. ? ICROS 2019.