Adaptive autoregressive model for the analysis of center of pressure in healthy subjects during quiet standing

Postural stability is defined as the ability to maintain or control body center of mass (CoM) in relation to the base of support to prevent falls and complete desired movements. The center of pressure (CoP) is an indirect measure of postural sway and measured in anterior-posterior (A-P) and medial-lateral (M-L) planes. The objective of this paper is to design a second order adaptive autoregressive (AR) model to estimate the model parameters and investigate the mean and peak frequencies from CoP data collected in both eyes open (EO) and eyes closed (EC) trials in healthy subjects. The performance of the AR model was compared to that of the fast Fourier transform (FFT). Peak frequency was observed to provide a better resolution than mean frequency. The second order adaptive AR model designed in this study offered an important metric, namely peak frequency, for postural stability analysis. It also provided means to estimate biomechanical parameters for postural stability, which would be the focus of further research