Parameter adjustments for optimizing signal integration using the FFT-DDI method

Abstract

Relative displacement measurements are needed in many practical applications, in particular to estimate damage from the associated strains and to follow and/or to control paths of moving objects. In many cases, such as monitoring of huge structures like tall bridges or of moving objects like vehicles, it is much easier to indirectly measure displacements by double-integrating an accelerometer signal, using some suitable numerical methods. However, such methods are susceptible to unknown initial conditions and to zero shifts, which may induce errors that are inadmissible in structural integrity evaluations and path control, so must be removed from the integrated signal. Many methods based on time-domain techniques are used in practice to decrease such zero-shifting errors; among them, the FFT-DDI method is used. Since this method is not well established yet, the purpose of this paper is to present some new techniques that can improve its efficiency.