A sliding mode observer to identify faulty FBG sensors embedded in composite structures for active vibration control

The increasing availability of small size and low cost sensors is orienting the world of smart structures towards a deep integration of a large number of these devices. This makes possible a more accurate knowledge of the dynamics of the structure, even if it requires the ability to manage an increasing number of information, potentially not consistent. In applications of vibration suppression, this circumstance must be avoided as measurements are used as a feedback in the control loop and therefore they can potentially capable of altering the stability of the controlled system and, in any case, to limit its performance. This work proposes a new algorithm for the automatic identification of inconsistent measurements due to sensors malfunctions, noise, wrong calibrations, etc. The approach is based on an innovative sliding mode observer that has been designed to seek faults and to avoid false positive results. The algorithm has been numerically and experimentally tested on a composite smart structure with 15 Fiber Bragg grating sensors embedded. Tests have been carried out considering different faults. Results confirm the effectiveness of the approach and allows to always identify faulty sensors.