A Fault Diagnosis Based Reconfigurable Longitudinal Control System for Managing Loss of Air Data Sensors for a Civil Aircraft

Abstract An integrated fault diagnosis based fault tolerant longitudinal control system architecture is proposed for civil aircraft which can accommodate partial or total losses of angle of attack and/or calibrated airspeed sensors. A triplex sensor redundancy is assumed for the normal operation of the aircraft using a gain scheduled longitudinal normal control law. The fault isolation functionality is provided by a bank of 6 fault detection filters, which individually monitor each of the 6 sensors using robust low order LPV residual generators. In the case of losses of up to 5 sensors, a fault estimation technique based on LPV estimators can be employed to reconstruct the missing sensor information necessary for gain scheduling. In the worst case of a total failure of all 6 sensors, a robust constant longitudinal control law is employed which ensures a basic longitudinal control performance. The proposed control architecture fulfils the basic requirements formulated in the Benchmark Problem in the RECONFIGURE project.