SENSOR AND ACTUATOR PLACEMENT FOR MODAL IDENTIFICATION

In modal identification, the use of different actuator and sensor locations results in different frequency response functions (FRFs) and consequently affects the modes shown on the FRF plots. This paper presents a method of placing sensors and actuators to obtain reliable measured data for estimating the modal parameters. The method is based on proposed controllability and observability measures for second-order linear systems, which are suitable for identification purposes and have a physical interpretation on the FRF plots. These measures, combined with an objective criterion, provide a method for ranking the effectiveness of alternative actuator and sensor distributions and hence a rational basis for choosing their locations. The method is applied successfully to the selection of actuator and sensor locations for a set of target modes for the structural characterisation of a simulated system. Finally, an iterative procedure for performing modal surveys is proposed.