Experimental application of transmissibility operators to fault detection

Abstract

This paper considers a technique for fault detection called sensor-to-sensor identification. Sensor-to-sensor identification takes advantage of freely available and unknown external (ambient) excitation to identify a sensor-to-sensor model (i.e., a transmissibility operator), which is independent of the excitation signal and the initial conditions of the underlying system. In the presence of unknown external excitation, the identified transmissibility operator is used to compute the sensor-to-sensor residual, which is the discrepancy between the predicted sensor output (based on the transmissibility operator) and the actual measurements. The sensor-to-sensor residuals are used to detect and diagnose faults in sensors and system dynamics. We consider an experimental setup consisting of a drum with two speakers and four microphones. Each speaker is an actuator, and each microphone is a sensor that measures the acoustic response at its location. Measurements from the four microphones are used to construct transmissibility operators, which in turn are used to detect changes in the dynamics of the drum by computing the resulting one-step residual.