Simultaneous fault detection, isolation and control tracking design using a single observer-based module

In this paper, the problem of simultaneous fault detection, isolation and tracking (SFDIT) design for linear continuous-time systems is considered. An H_∞/H_- formulation of the SFDIT problem using a dynamic observer is developed. A single module based on a dynamic observer is designed which produces two signals, namely the residual and the control signals. The SFDIT module is designed such that the effects of disturbances and reference inputs on the residual signals are minimized (for accomplishing fault detection) subject to the constraint that the transfer matrix function from the faults to the residuals is equal to a pre-assigned diagonal transfer matrix (for accomplishing fault isolation), while the effects of disturbances, reference inputs and faults on the specified control output are minimized (for accomplishing fault-tolerant control and tracking problems). Sufficient conditions for solvability of the problem are obtained in terms of linear matrix inequality (LMI) feasibility conditions. Simulation results for an autonomous unmanned underwater vehicle (AUV) illustrate the effectiveness of our proposed design methodology.