A study of Savitzky-Golay filters for derivatives in primary shock calibration

Abstract

This manuscript reports the result of an investigation into two types of digital filters for numerical differentiation of the displacement signal in the case of primary shock calibration of accelerometers. The first is a difference method with a 4th-order Butterworth lowpass (4th BW) filter; the other is a Savitzky-Golay (S-G) filter, which applies a moving polynomial approximation. The computational comparison was applied to low and high amplitude shocks using known excitation functions. Each sum of residuals was compared for the optimized conditions of the 4th BW and S-G filters. The results of computer simulation indicated that the S-G filters exhibited better performance for the derivatives than the 4th BW filters. In addition, an analytical comparison using experimental vibration data also indicated that the S-G filters exhibited better derivative characteristics than the 4th BW filters.