Journal of Biomedical Engineering Research (대한의용생체공학회:의공학회지)

The Korean Society of Medical and Biological Engineering (대한의용생체공학회)
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Design of an Optimal Adaptive Filter for the Cancellation of M-wave in the EMG Controlled Functional Electrical Stimulation for Paralyzed Individuals

마비환자의 근전도제에기능적전기자극을 위한 M-wave 제거용 최적적응필터 설계

  • Yeom Hojoon (Institute of Medical Engineering, Yonsei University) ;
  • Park Youngcheol (Department of Information Technology, Yonsei University) ;
  • Lee Younghee (Department of Rehabilitation Medicine, College of Medicine, Yonsei University) ;
  • Yoon Youngro (Department of Biomedical Engineering, Yonsei University) ;
  • Shin Taemin (Department of Biomedical Engineering, Yonsei University) ;
  • Yoon Hyoungro (Department of Biomedical Engineering, Yonsei University)
  • 염호준 (연세대학교 의료공학연구원) ;
  • 박영철 (연세대학교 정보기술학부) ;
  • 이영희 (연세대학교 원주의과대학 재활의학교실) ;
  • 윤영로 (연세대학교 의공학부) ;
  • 신태민 (연세대학교 의공학부) ;
  • 윤형로 (연세대학교 의공학부)
  • Published : 2004.12.01
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Abstract

Biopotential signals have been used as command in systems using electrical stimulation of motor nerves to restore movement after an injury to the central nervous system (CNS). In order to use the voluntary EMG (electromyography) among the biopotentials as a control signal for the electrical stimulation of the same muscle for CNS injury patients, it is necessary to remove M-wave of having high magnitude from raw data. We designed an optimal filter for removing the M-wave and preserving the voluntary EMG and showed that the optimal filter is eigen filter. We also proved that the previous method using the prediction error filter(PEF) is a suboptimal filtering in the sense of preserving the voluntary EMG. On basis of the data obtained from a model for M-wave and voluntary EMG and from actual CNS injury patients, with false-positive rate analysis, the proposed adaptive filter showed a very promising performance in comparison with previous method.

중추신경계손상으로 인하여 약화된 근육기능을 회복하기 위한 전기자극의 제어신호로 생체신호를 이용하고 있다. 생체신호중에서 마비된 근육에서 발생되는 자발적이면서 근수축을 하기에 부족한 자발근전도신호로 전기자극의 강도를 조절해야 하는 경우, 전기자극에 의해 발생되어 자발근전도신호에 섞이는 M-wave를 제거해야 한다. 본 연구에서는 M-wave를 제거하고 동시에 자발근전도신호의 크기를 보존하기 위한 최적필터를 설계하였고 최적필터의 계수는 입력 공분산 행렬의 최소고유치에 해당하는 고유벡터가 됨을 보였으며. inverse Power methd(IPM)을 사용하여 이를 적응적으로 구현하는 과정을 통해 기존의 예측오차필터 방법이 부최적 방법임을 보였다. 최적필터의 성능을 평가하기 위하여 모의데이터에 대한 false-positive rate를 측정하여 분석하였으며, 실험결과는 최적필터가 이전에 연구되었던 예측오차필터에 비해 효과적으로 M-wave를 제거할 수 있음을 보여준다.

Keywords

References

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