The Journal of Korean Institute of Electromagnetic Engineering and Science (한국전자파학회논문지)

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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Vital Sign Detection in a Noisy Environment by Undesirable Micro-Motion

원하지 않는 작은 동작에 의한 잡음 환경 내 생체신호 탐지 기법

  • Choi, In-Oh (Department of Electrical Engineering, Pohang University of Science and Technology) ;
  • Kim, Min (Department of Electrical Engineering, Pohang University of Science and Technology) ;
  • Choi, Jea-Ho (Department of Electrical Engineering, Pohang University of Science and Technology) ;
  • Park, Jeong-Ki (Department of Electrical Engineering, Pohang University of Science and Technology) ;
  • Kim, Kyung-Tae (Department of Electrical Engineering, Pohang University of Science and Technology)
  • 최인오 (포항공과대학교 전자전기공학과) ;
  • 김민 (포항공과대학교 전자전기공학과) ;
  • 최재호 (포항공과대학교 전자전기공학과) ;
  • 박정기 (포항공과대학교 전자전기공학과) ;
  • 김경태 (포항공과대학교 전자전기공학과)
  • Received : 2019.04.01
  • Accepted : 2019.04.25
  • Published : 2019.05.31
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Abstract

Recently, many studies on vital sign detection using a radar sensor related to Internet of Things(IoT) smart home systems have been conducted. Because vital signs such as respiration and cardiac rates generally cause micro-motions in the chest or back, the phase of the received echo signal from a target fluctuates according to the micro-motion. Therefore, vital signs are usually detected via spectral analysis of the phase. However, the probability of false alarms in cardiac rate detection increases as a result of various problems in the measurement environment, such as very weak phase fluctuations caused by the cardiac rate. Therefore, this study analyzes the difficulties of vital sign detection and proposes an efficient vital sign detection algorithm consisting of four main stages: 1) phase decomposition, 2) phase differentiation and filtering, 3) vital sign detection, and 4) reduction of the probability of false alarm. Experimental results using impulse-radio ultra-wideband radar show that the proposed algorithm is very efficient in terms of computation and accuracy.

최근 사물인터넷(internet of things: IoT) 스마트 홈 시스템과 관련하여 레이다 기반의 다양한 생체신호 탐지 기법들이 개발되고 있다. 생체신호는 폐에 의한 호흡수와 심장에 의한 심장박동수로 정의되며, 이는 일반적으로 흉부 또는 등의 미세한 움직임을 야기한다. 이때, 이 미세한 움직임은 레이다 수신신호의 위상을 변화시키기 때문에, 생체신호는 주로 위상 변화에 대한 스펙트럼 분석을 통해 탐지된다. 하지만, 호흡수와 달리 심장박동수에 의한 위상 변화는 매우 미약하기 때문에 실제 측정환경에서는 다양한 원인들로 인해 심장박동수가 오탐지될 확률이 매우 높다. 따라서 본 논문에서는 먼저 생체신호 오탐지를 야기하는 원인들을 분석한 후, 이를 바탕으로 효과적인 생체신호 탐지 기법을 제안한다. 제안된 기법은 크게 1) 위상 분리, 2) 위상 미분 및 필터링, 3) 생체신호 탐지, 그리고 4) 오탐지율 감소 단계로 구성되며, IR-UWB(Impulse-Radio Ultra-Wideband)를 사용한 실험 결과에서 보다 효율적이고 정확하게 생체신호가 탐지됨을 확인할 수 있었다.

Keywords

JJPHCH_2019_v30n5_418_f0001.png 이미지

그림 1. 생체신호 탐지를 위한 구조 Fig. 1. Geometry for vital sign detection.

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그림 2. IR-UWB 레이다 및 스마트 시계 Fig. 2. IR-UWB radar and smart watch.

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그림 3. IR-UWB 레이다 측정 결과 Fig. 3. Measurements using IR-UWB radar.

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그림 4. 위상 분리 예시 Fig. 4. Example of phase decomposition.

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그림 5. 스펙트럼 분석 예시 Fig. 5. Example of spectrum analysis.

JJPHCH_2019_v30n5_418_f0006.png 이미지

그림 6. 실시간 생체신호 탐지를 위한 구조 Fig. 6. Framework for real-time vital sign detection.

JJPHCH_2019_v30n5_418_f0007.png 이미지

그림 7. IR-UWB 레이다 측정 결과 Fig. 7. Measurements using IR-UWB radar.

표 1. 실험 변수들 Table 1. Experiment parameters.

JJPHCH_2019_v30n5_418_t0001.png 이미지

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