Auxiliary input design for stochastic subspace-based structural damage detection

This paper 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 paper, the method of “rotated inputs” 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 the auxiliary input to improve the subspace-based fault detection methodology.

► Improving the subspace-based fault detection method. ► Detecting the system order changes. ► Strengthening the effect of weak modes on the residual. ► For a group of systems, some fault cannot be detected using random inputs. ► The rotated inputs are implemented to better excite weak modes of the system and finally to get better detection results.