Trial on Low-Pass Filter Design for Bio-Signal Based on Nonlinear Analysis

Toru Tanimura¹, Yusuke Jono¹, Takayuki Hirata¹, Yasuyuki Matsuura² and Hiroki Takada^1*

¹Department of Human and Artificial Intelligent Systems, Graduate School of Engineering, University of Fukui, 3-9-1 Bunkyo, Fukui, Fukui 910-8507, Japan
²Department of Cross Cultural Studies, Gifu City Women's College, 7-1 Hitoichiba Kitamachi, Gifu, Gifu 501-0192, Japan
^*E-mail address: takada@u-fukui.ac.jp

(Received January 22, 2019; Accepted July 11, 2019)

Abstract. The nonlinearity of the mathematical model describing the cerebral blood flow dynamics and the body sway in the prefrontal cortex was investigated experimentally. The measured bio-signal data were smoothed with each low-pass filter. The signal was set to 0.1-2 Hz for the cerebral blood flow dynamics and to 0.1-20 Hz for the body sway. Nonlinearity was observed in the biological signal when the cut-off frequency of the low-pass filtering was 0.2 Hz or less, and while the body sway was 0.5 Hz or less, and was considered as a stochastic differential equations.

Keywords: Nonlinearity, Bio-Signal, Surrogate Data, Low-Pass Filter, Wayland Algorithm