Section: New Results

Instability monitoring of aeronautical structures

Subspace identification for hinged-blades helicopters

Participants : Ahmed Jhinaoui, Laurent Mevel.

In this work, an extension of the output-only subspace identification, to the class of linear periodically time-varying (LPTV) systems, is proposed. The goal is to identify a useful information about the system's stability using the Floquet theory which gives a necessary and sufficient condition for stability analysis [24] .

Optimal input design for identification and detection

Participants : Alireza Esna Ashari, Laurent Mevel.

Output only techniques rely on the presence on unknown turbulence, which may or may not be enough to excite the system. A new approach for applying artificial input to the system for maximizing detection and identifiability has been developed. This work considers the problem of auxiliary input design for subspace-based fault detection methods. In several real applications, particularly in the damage detection of mechanical structures and vibrating systems, environment noise is the only input to the system. In some applications, white noise produces low quality output data for the subspace-based fault detection method. In those methods, a residual is calculated to detect the fault based on the output information. However, some modes of the system may not influence the outputs and the residual appropriately if the input is not exciting enough for those modes. In this work, rotated inputs method is implemented to excite the system modes. In addition to produce a residual more sensitive to the weak modes, it is possible to detect system order changes due to the fault using the rotated inputs. Simulation results demonstrate the efficiency of injecting these auxiliary inputs to improve the subspace-based fault detection methodology [22] . This work is funded by FP7-NMP Large Scale Integrated Project IRIS.