On the filtering and smoothing of biomechanical data

This paper deals with the issue of filtering and smoothing biomechanical data for the purpose of implementing the so-called inverse solution. First, the filtering method using a low-pass zero-phase-shift Butterworth filter is discussed, covering key points like the phase shift, the choice of the order and the cutoff frequency using a residual analysis. Next, a new method for smoothing biomechanical data is proposed by combining an adaptive cubic spline and least squares algorithm. The performance of the proposed smoothing technique is compared to that of the Butterworth filter using experimental data.