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Simplified appraisal method for fatigue on sitting for extended periods by using finger plethysmogram

E. FUJITA1, Y. OGURA1, N. OCHIAI1, T. KAMEI2,* , K. MURATA3, Y. UENO4, SHIGEHIKO KANEKO5

Affiliation

  1. Deltatooling Co., Ltd. 3-1 Taguchi-Kenkyu-Danchi, Higashi-Hiroshima, Hiroshima 739-0038, Japan
  2. a Shimane Institute of Health Science 223-7 Enya-cho, Izumi, Shimane 693-0021, Japan
  3. Kanazawa University Graduate School of Medical Science 13-1 Takaramachi, Kanazawa, Ishikawa 920-0934, Japan
  4. Faculty of Engineering, Chiba Institute of Technology 2-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
  5. School of Engineering, The University of Tokyo7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

Abstract

For the purpose of quantifying and indicating the degree of fatigue as a result of sitting in an automobile seat for long periods of time, a method was developed by using a baseline oscillation and the amplitude of a finger plethysmogram. Between a finger plethysmogram and the degree of fatigue, there is about one hundred times difference in a fluctuation cycle. So, an idea was proposed to convert a finger plethysmogram into a gradient of comprehensive change to make fluctuation cycle scales easily comparable. The gradients of the square of the finger plethysmogram amplitude were converted into absolute values. Then, we drew a fatigue curve based on the results calculated at 18-second integrated values of the time series signals. This curve and the muscle fatigue curve from subjective judgment were in general accord. By using a finger plethysmogram featuring high sensitivity to the fatigue progress, differences in various subjects and seat performances could be found on this fatigue curve using only a 30-minute fatigue test. This new method has made it possible to greatly shorten the measurement time necessary to predict fatigue level by sensory evaluation..

Keywords

Plethymogram, Fatigue curve, Sensor, Muscle fatigue.

Submitted at: March 13, 2008
Accepted at: May 14, 2008

Citation

E. FUJITA, Y. OGURA, N. OCHIAI, T. KAMEI, K. MURATA, Y. UENO, SHIGEHIKO KANEKO, Simplified appraisal method for fatigue on sitting for extended periods by using finger plethysmogram, Journal of Optoelectronics and Advanced Materials Vol. 10, Iss. 5, pp. 1290-1294 (2008)