Synchrosqueezing Characterize Non-stationary Signals: Application on Gait-Vertical Ground Reaction Force

Signal is a physical quantity we can measure like gait vertical ground reaction force. However, the latter are such non- stationary signals require a deep understanding of their instantaneous amplitude, phase and frequency. From this, one can model its stationary and non- stationary part and approximate the noise. In addition, one can practice such features for inter-subject classification of the vertical ground reaction force signals like between normal and pathological. Not to add, one objective could also concentrate in intra-subject classification like between usual gait and gait associated with cognitive tasks for the same subject as this paper mainly concerns. For that purpose, Synchrosqueezing of time-frequency representation is being used to spot its power in non-stationary signal analysis and classification. This technique also helped in developing an accurate detection of outliers within such time series signal like when subjects encounter turning points during walking. All this would help in a correct assessing treatment effectiveness and précising the stage of disease. In addition, this would be a starting point for having accurate parameters in elderly fall detection.