The application of non-linear methods to the analysis of finger plethysmograms for ergonomics

Abstract

Chaotic fluctuations in many biological signals have attracted considerable attention since in the assessment of these properties, chaos analysis can extract more informative knowledge than conventional analysis methods such as spectral analysis. Biological signals, particularly chaotic fluctuation of finger plethysmograms, were used to assess the psychophysiological state of workers in ergonomic research of Japan. This paper introduces the method of chaos analysis and the results of our two studies. In both studies, it was shown that chaotic fluctuation (largest Lyapunov exponent) in finger plethysmograms might have the potential to assess the mental workload of workers and to prevent the occurrence of human error. In the future, if we can determine how chaotic fluctuations in finger plethysmograms are related physiological mechanisms, chaos analysis is expected to make a great contribution to various fields.