Spatial filter design for observation spillover suppression (Introduction of measures of modal observability and its application to health monitoring)

This paper describes a health monitoring methodology using a spatial filter design for observation spillover suppression with measures of modal observability. The spatial filter can be realized using a number of sensors attached to a structure that is less than the number of target modes. Measures of modal observability as criteria for designing the optimal filter in an engineering sense have been proposed by the authors. In vibration testing, if it is possible to make the desired spatial filter by adjusting only one sensor location from among many sensor placements, this affords a practical advantage. In this study, measures of modal observability are used to select one sensor location that should be adjusted, and then the desired spatial filter can be designed. Spatial filtering is then performed for the bending vibration of a cantilever beam. In this study, when the mass and rigidity of structures change, this is defined as structural damage. The feasibility of this monitoring methodology for monitoring health and detecting structural damage using spatial filtering is verified by vibration testing of the cantilever beam.