Etsunori Fujita

Noninvasive Biological Sensor System for Detection of Drunk Driving

Systems capable of monitoring the biological condition of a driver and issuing warnings during instances of drowsiness have recently been studied. Moreover, many researchers have reported that biological signals, such as brain waves, pulsation waves, and heart rate, are different between people who have and have not consumed alcohol. Currently, we are developing a noninvasive system to detect individuals driving under the influence of alcohol by measuring biological signals. We used the frequency time series analysis to attempt to distinguish between normal and intoxicated states of a person as the basis of the sensing system.

Noninvasive biological sensor system for detection of drunk driving

Systems capable of monitoring the biological condition of a driver and issuing warnings during instances of drowsiness have recently been studied. Moreover, many researchers have reported that biosignals, such as brain waves, pulsation waves, and heart beat are different between people who have and have not consumed alcohol. Currently, we are developing a noninvasive system to detect individuals driving under the influence of alcohol by measuring biosignals. In this paper, a new algorithm to distinguish between the normal and intoxicated state of a person is proposed as the basic theory of the sensing system.

Moving simulation of vibration systems using permanent magnets

This paper presents results obtained in moving simulations for a new vibration system with permanent magnets. The magnetic field distributions, the force acting upon the permanent magnets and the vibration mechanism of the magneto-spring are made clear in solving the coupled problem of the magnetic field and motion equations. The developed magneto-spring works to keeping a constant resonance frequency without active control.

Development of a condition monitoring system using an air-pack type pressure sensor for bedridden patients in a supine position

This paper proposes an online biological signal measurement system with an air-pack-type pressure sensor (APS) to monitor the condition of supine patients from pulse activity. The system enables estimation of three physiological signals corresponding to pulse pressure waves, pulse beats and respiratory waves from measurements taken and filtered using the APS, which has mechanical characteristics similar to the impedance characteristics of human muscle and can also be fitted with a mattress pad to prevent decubitus. In this study, the physiological significance of signals obtained through the APS was determined by comparing them with signals measured using commercial medical devices. The results showed that the correlations of pulse pressure waves, pulse beats and power spectral densities for respiratory waves between signals measured using the APS and those measured using commercial sensors were 0.84, 0.84 and 0.98, respectively. It was therefore concluded that the proposed system is suitable for outputting pulse pressure waves, pulse beats and respiratory waves.

Fluctuation analysis of finger plethysmograms related to various conditions

This study developed an analytical method for estimating and presenting the rating of perceived exertion (RPE) by using fluctuation analysis of largest Lyapunov exponent and heart rate variability. The method was applied to method to analyze a series of experiments conducted in various conditions including the use of a variety of driving seats to observing exertion and fatigue processes during a longer sitting a seat. We described the generating rate of and driving cause of the fatigue processes, respectively, by differentiation and acceleration of the RPE relations. We further explored the acceleration by wavelet analysis and found characterizing categories in relation to individuals and conditions.

Development of a magnetic seat sensor for monitoring condition of a car driver

The purpose of our research is to develop the prevention system of a car drivers dozing off at the wheel by a magnetic sensor, which is built in drivers seats of cars and trucks. Torsion bars are ones of the parts of the car drivers seat. Torsion stress occurs in these bars when a car driver sits on the seat, and these bars works as a cushion to the driver. In this research, we tried to measure difference of magnetic properties of those torsion bars because of the torsion stress by a magnetic sensor to apply it to monitor car drivers condition.

Development of simplified appraisal method of awakening degree by fluctuation analysis via brain wave and finger plethysmogram

1.はじめに 不注意な運転や居眠り運転は疲労やストレス から生じることが多く,覚醒度も低い.覚醒度が 低くなるのは疲労やストレスを原因とするもの が多い.そこで,疲労の進行を緩和し,高い覚醒 状態を長時間維持する技術が求められる. 本報告では脳波と脈波のゆらぎ解析による簡 易的な覚醒状態の評価法と,高い覚醒状態を長時 間維持するためのシート特性について報告する. 2.実験方法 被験者の覚醒度と疲労度を評価するために,指 尖容積脈波と脳波を計測する.指尖容積脈波の計 測器は赤外線発光ダイオードとフォトトランジ スタで構成されている.計測データは A/D変換を 行った後 PCにて処理を行う.サンプリング周波 数は 200Hzで分解能は 12ビットである. 脳波計測は簡易脳波計測器(ヒューテックエレ クトロニクス製 FM-515A)を用いる.この計測器 はθ波(4~6Hz),α1 波(7~8Hz),α2 波(9~ 11Hz),α3波(12~13Hz),β波(17~26Hz)をそ れぞれ 1秒毎に計測することができる. 図 1は実験に使用したシートの体圧分布を示す. シート Aは,バックが肩甲骨から腸骨稜までの腰 腸肋筋を支持する体側支持型シートである.シー ト B もシート A と同様の体側支持型のシートで ある.シート C はシート B に腰椎支持を付加し たものである.シート Dは体圧分散型のシートで ある.シート E はシート D に腰椎支持を付加し たものである.シート Fは腰椎部の支持圧力が高 い立位の脊柱形状を維持する姿勢維持型のシー トである.被験者は脳波計測の際にアーチファク トの少ない 43 歳の成人健常男性1名で行った. 本実験は,支持特性の異なるシートで同一の被験 者において本研究で提案する簡易評価方法で覚 醒度に有意な差が生じるかを検証した. 2-1.覚醒状態検出実験 全身振動環境下でシートに着座した被験者の 脈波と脳波を計測し,覚醒状態検出実験を行った. 励振条件は大型セダンで高速道路を走行した 際の実車波形データで,加振台のプラットフォー ム上でランダムに発生する加速度の P-P 値が約 0.016~0.058Gの上下方向の励振波である. 生体信号の採取は覚醒状態と眠気状態で行い, それぞれ脳波と脈波を 30分間計測した. 2-2.着座疲労回復効果の確認実験 実験時間帯は 11時~13時の間で 1時間の覚醒 状態検出実験を行い,開始から 30 分経過時に被 験者の腰部へ 30分間の圧力刺激を付加した.