Design of an Active Fault Tolerant Control and Polytopic Unknown Input Observer for Systems described by a Multi-Model Representation

In this paper, an active Fault Tolerant Control (FTC) strategy is developed to systems described by multiple linear models to prevent the system deterioration by the synthesis of adapted controllers. First, a Polytopic Unknown Input Observer is synthesized for providing actuator fault estimation. The actuator fault estimation is used in a FTC scheme which schedules some predefined state feedback gains. These gains are performed through LMI both in fault-free and faulty cases in order to preserve the system performances over a wide operating range. For each separate actuator, a pole placement is designed by pole clustering. The effectiveness and performances of the method have been illustrated in simulation considering a hydraulic system: a three-tank system.