Output Feedback FTC Scheme For Linear Parameter

Abstract

The proposed research has been carried out for an Active Fault Tolerant Control (FTC) of Linear Parameter Varying (LPV) systems using output feedback mechanism. Output feedback is a practical approach due to the fact that all the plant states are not accessible or measurable, therefore estimating the unknown states and maintaining the closed loop stability in an LPV framework is closer to the control of nonlinear systems. At the same time, it utilizes the mature nature of linear control theory. In this research, LPV observers in LMI framework have been designed for affine LPV plant, using two different LPV approaches namely affine and polytopic, in order to estimate the unknown states. These estimated states are used as a feedback to LPV controller. Integral sliding mode controller in LPV framework has been designed along with control allocation scheme to control the controlled states as well as to counter for actuators faults and failures. It has been assumed that Fault Detection and Isolation unit, also called FDI, is providing updated actuator faults or failures information to the control allocation (CA) scheme. Detailed performance and stability of the proposed control scheme has been checked in fault-free case, i.e. nominal condition, as well as in the situation when actuator fault occurs. To validate the proposed output feedback FTC mechanism, an LPV model of longitudinal plant of aircraft, taken from the literature, has been considered as a benchmark in the simulation. The simulation results show that the system is quadratically stable and give good tracking capability by the LPV controller-observer pair in nominal as well as in actuator’s fault or failure situation.