Time series analysis of body sway caused by several matrix-shaped tactile stimuli on body trunk

Postural control is an essential function of the human body that uses several senses and information from the body as input, processes the input and then provides output to the muscles for control. In this study, we examine a method wherein several matrix-shaped tactile stimuli (MSTS) located on the skin of the trunk are used to away subjects’ bodies. To clarify the relationship between body sway and the MSTS, the subjects were tracked using a high-speed camera, a foot pressure distribution measuring instrument, and two acceleration sensors. Owing to the nature of using human subjects, the resulting data had high variance; therefore, each trial data set exhibits different features. The effects of each MSTS on body sway and the dynamics of body sway are discussed and evaluated here. Additionally, we propose a single trial analysis method based on the clustering based Gaussian mixture model and smoothing filtering.