Modal filtering for simply supported plate using equally segmented piezoelectric film

A method to measure the modal coordinates of a simply supported rectangular plate using an equally segmented piezoelectric film is studied. Modal sensors which can measure specific modal coordinates by shaping distributed piezoelectric sensors were proposed by Lee et al. (1990). However, basically, it can be only applied to one dimensional vibrations and only measure the specific modal coordinates corresponding to the shape of the sensor. In this paper, we propose a method, in which estimated modal coordinates are obtained by the sum of appropriately weighted sensor signals from the segmented piezoelectric film. This method can be easily applied to two dimensional vibrations and can measure arbitrary modal coordinates by selecting the weight. In this paper, the weight is determined to minimize a cost function. The orthogonality of the unit modal sensing signal vectors for a simply supported rectangular plate with an equally segmented piezoelectric film is proven, and the transpose of the unit model sensing signal matrix is chosen as the weight. Effects of aliasing caused by finite segmentation are also discussed. Simulation is shown to prove efficiency