Modal Identification Using a Roving Actuator and a Fixed Sensor

Abstract

Experimental modal analysis typically use an actuator to apply input force on a structure and multiple fixed sensors to record the responses of the structure. An appealing alternative to using many stationary sensors is to use a roving actuator and a single fixed sensor. In this study, a method to identify the modal properties of a beam from the input-output data obtained using a roving actuator and a fixed accelerometer is presented. In multiple test setups, the roving actuator applies input forces at different points on the beam, while the fixed sensor measures the response at a particular location of the beam during all tests. Using the accumulated input-output measurements, the modal identification of the beam is performed in two distinct steps: identification of natural frequencies and modal damping ratios, followed by an estimation of mode shape components at all excited degrees of freedom. The variability in the estimated modal parameters due to the presence of measurement noise is studied using Monte Carlo simulations.