Simultaneous disturbance attenuation and fault detection using proportional integral observers

This paper considers the design of a proportional integral observer (PIO) for simultaneous disturbance attenuation and fault detection. Unlike the proportional observer, an integral observer alone suffices to achieve good convergence and filtering properties when sensor noise is present in the system. On the other hand, a proportional integral observer makes it possible to decouple the modeling uncertainties while estimating the states and faults with satisfactory convergence properties. We show that a generalized PIO structure, a proportional integral fading observer, facilitates the design procedure for achieving the above goal.