One-dimensional distributed modal sensors and the active modal control for planar structures

Abstract

This paper discusses distributed parameter sensors designed to extract vibration modes of a structure, as well as its active modal control. Compared to conventional point sensors such as accelerometers or displacement sensors, the distributed parameter sensors are superior to point sensors provided that they are properly designed. First, this paper overviews a conventional modal filter method using point sensors, and enumerates the problems they possess. To overcome the drawbacks of the point sensor-based modal filtering, a novel modal filtering technique based upon distributed parameter PVDF film sensors is proposed. This paper begins by discussing a design methodology for modal filtering using two-dimensional distributed sensors. Then, taking into consideration the applicability of the sensors, a design procedure for modal filtering using one-dimensional sensors is presented, the number, location, and shaping functions for the one-dimensional modal sensors being clarified. Furthermore, the modal filtering using the one-dimensional sensors is found to be applicable for two-dimensional structures subject to any “classical” boundary condition. Experimental results verify the capability of the desired modal filtering for both isolated and degenerate structural modes. Finally, using the modal sensors, experiments on active modal control are conducted, showing a significant suppression of the targeted mode without causing instability of the control system.