104 Int. J. Automation and Control, Vol. 10, No. 2, 2016 Copyright © 2016 Inderscience Enterprises Ltd. Adaptive fault tolerant control of singularly perturbed systems with actuator faults Adel Tellili* Research Unit MACS, Higher National Engineering School at Gabès, Tunisia and Higher Institute of Technological Studies at Djerba, Avenue 7 novembre – 4116 Midoun Djerba, Tunisia Email: adel_tellili@lycos.com *Corresponding author Nouceyba Abdelkrim and Amina Challouf Research Unit MACS, Higher National Engineering School at Gabès, Tunisia and Higher Institute of Industrial Systems at Gabès, University of Gabès, Rue Slaheddine El Ayoubi – 6032 Gabès, Tunisia Email: nouceyba.naceur@laposte.net Email: amina_chalouf@yahoo.fr Mohamed Naceur Abdelkrim Research Unit MACS, Higher National Engineering School at Gabès, Tunisia and Higher National Engineering School at Gabès, University of Gabès, Avenue Omar Ibn El Khattab – Zerig – 6029 Gabès, Tunisia Email: naceur.abdelkrim@enig.rnu.tn Abstract: This paper deals with the adaptive fault tolerant control for linear time-invariant singularly perturbed systems against actuator failures and external disturbances. By time-scale decomposition using singular perturbation method, the full-order system is decomposed into slow and fast subsystems. An ε-dependent fault tolerant controller for the global system is first designed. To avoid numerical stiffness, a simplification based on singular perturbation parameter decoupling is secondly carried out using the reduced subsystems and some manipulations of the Lyapunov equations. The resulting control system is fault tolerant in that, it provides guaranteed asymptotic stability in presence of external disturbances when all control components are operational as well as when actuator failures occur. The stability is guaranteed based on the Lyapunov stability theory provided the singular perturbation parameter is sufficiently small. A numerical example is given to illustrate the proposed method, where the efficiency of the developed approach will be compared with a reliable H ∞ control technique.