DEVELOPMENT OF AN ON-BOARD FAULT TOLERANT CONTROL STRATEGY WITH APPLICATION TO THE GARTEUR AG16 BENCHMARK J. Cieslak * 1 + , D. Henry * 1 , A. Zolghadri * 1 * Automatic Control Group - IMS UMR 5218 CNRS - Université Bordeaux I - 351 cours de la libération, 33405 Talence Cedex, France - email :{ jerome.cieslak, david.henry, ali.zolghadri}@laps.ims-bordeaux.fr + Corresponding author P. Goupil ** 1 ** Airbus France EYC-CC – Flight Control System email: philippe.goupil@airbus.com Abstract: This paper presents a Fault Tolerant Control (FTC) strategy to provide a highly reliable reconfigurable control capacity for safety critical systems in faulty situations. The paper describes mainly the status of an on-going research work which is undertaken within GARTEUR FM-AG(16) 2 Action Group. The developed techniques are applied to a faulty scenario of a realistic nonlinear benchmark of a large transport aircraft. The goal is to provide a “self-repairing” capability to enable the pilot to land the aircraft safely in the event of a stabilizer fault. Once the fault is detected by the Fault Detection and Isolation (FDI) unit, a fault compensation loop is activated. A key feature of the proposed strategy is that the design of FTC loop is done independently of the nominal autopilot and the nominal Flight Control System (FCS) in place. Nonlinear simulation results demonstrate the capability and viability of the proposed active FTC scheme. Copyright © 2007 IFAC Keywords: Fault Tolerant Control, Fault Detection and Isolation, Flight Control, Nonlinear System 1. INTRODUCTION During the last two decades, Fault Tolerant Control (FTC) law design based on a possible known fault scenario for aeronautical applications has been widely studied (see for instance (Moerder et al., 1989; Huzmezan & Maciejowski, 1998; Chen & Patton, 2001; Zhang & Jiang, 2002)). An active FTC (AFTC) system requires its control law to react to faults through reconfiguration and Fault Detection and Isolation (FDI) modules (Staroswiecki & Gehin, 2001; Chen & Patton, 2001). The FDI unit is supposed to detect, and diagnose any relevant failure which could lead to flight performance degradation. This shall be done sufficiently early and in compliance with the stringent operational and flight dynamics constraints, for adequate safe recovery 1 Members of FM-AG(16) Action Group FTC (GARTEUR) 2 FM-AG(16) (Flight Mechanics Action Group 16) is a part of the Group for Aeronautical Research and Technology in EURope (GARTEUR) programme. actions and to improve the situation awareness. More recently, Linear Parameter Varying (LPV) FTC laws have been proposed (Ganguli et al., 2002; Gaspar et al., 2005). Here the idea is to use the residual output of the FDI filter jointly with some subspace of the system states as scheduling parameters of the LPV fault tolerant controller. The main difficulty that arises when integrating the different units to build a reliable active FTC law, is that each individual block is assumed to operate perfectly and is readily available to provide decisions/actions instantaneously to other blocks. This implies some interactions between the reconfigurable controller and the FDI unit as mentioned in (Zhang & Jiang, 2006) and in (Cieslak et al., 2006). Several works have been dedicated to combining fault tolerant controller and a diagnostic filter. In (Campos Delagado et al., 2004), the authors use the standard H  setting to design a nominal controller and a robust detection filter. In this configuration, the primal Youla parameterization of