PASSIVE ROBUST FAULT DETECTION USING A FORWARD-BACKWARD TEST

Abstract

The problem of passive robust model based fault detection of dynamic systems using interval observers has been mainly addressed checking if the measured output is inside the interval of possible estimated outputs obtained considering uncertainty on model parameters. This task could be computationally expensive. In this paper, a mixed approach consisting in determining a computationally cheaper inner approximation of the estimated output interval, based on considering only the vertices of parameter uncertainty region (forward test), is combined with a parameter consistency check when the real measured output falls outside the inner solution (backward check). The backward check is implemented using interval constraint satisfaction algorithms, which can perform efficiently in deciding if the measured output is consistent with the interval model. Finally, this approach will be tested on a gas turbine nozzle servosystem.