Pre-publication manuscript accepted by Mechanical Systems and Signal Processing, January 2008. 1 Delayed, Multi-Step Inverse Structural Filter for Robust Force Identification

An extension of the Inverse Structural Filter (ISF) force reconstruction algorithm is presented that utilizes data from multiple time steps simultaneously to improve the accuracy and robustness of the ISF. The ISF algorithm uses a discrete-time system model and the measured response to estimate the input forces acting on a structure. The proposed algorithm, dubbed the Delayed, Multi-step ISF (DMISF), is compared with the original ISF and with the Sum of Weighted Accelerations Technique (SWAT) and the classical Frequency Domain Inverse (FD) method in terms of both accuracy and sensitivity to errors in the forward system model. The SWAT and ISF algorithms are capable of estimating the forces acting on a structure in real time, or when time data is available over such a short duration that frequency domain methods cannot be applied effectively. The new DMISF can be created from a forward system model identified by any standard modal analysis algorithm, so one can leverage expertise with a particular system identification methodology. In contrast, the previously presented ISF was derived directly from experimental data. The theory behind the algorithms is presented, after which their performance is demonstrated using laboratory test data. The results of