Journal of Biomedical Engineering Research (대한의용생체공학회:의공학회지)

The Korean Society of Medical and Biological Engineering (대한의용생체공학회)
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Sensitivity Analysis and Optimization of Design Variables Related to an Algorithm for Loss of Balance Detection

균형상살 검출 알고리즘에서 검출과 관련된 설계변수의 민감도 해석 몇 최적화

  • Ko, B.K. (School of Mechanical Engineering, Pusan National University) ;
  • Kim, K.H. (Research Institute of Mechanical Technology, Pusan National University) ;
  • Son, K. (School of Mechanical Engineering, Pusan National University)
  • 고병규 (부산대학교 기계공학부) ;
  • 김광훈 (부산대학교 기계기술연구원) ;
  • 손권 (부산대학교 기계공학부)
  • Received : 2010.09.20
  • Accepted : 2010.12.15
  • Published : 2011.02.28
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Abstract

This study suggested an optimized algorithm for detecting the loss of balance(LOB) in the seated position. And the sensitivity analysis was performed in order to identify the role of each design variable in the algorithm. The LOB algorithm consisted of data processing of measured signals, an internal model of the central nervous system and a control error anomaly(CEA) detector. This study optimized design variables of a CEA detector to obtain improved values of the success rate(SR) of detecting the LOB and the margin time(MT) provided for preventing the falling. Nine healthy adult volunteers were involved in the experiments. All the subjects were asked to balance their body in a predescribed seated posture with the rear legs of a four-legged wooden chair. The ground reaction force from the right leg was measured from the force plate while the accelerations of the chair and the head were measured from a couple of piezoelectric accelerometers. The measured data were processed to predict the LOB using a detection algorithm. Variables S2, h2 and hd are related to the detector: S2 represents a data selecting window, h2 a time shift and hd an operating period of the LOB detection algorithm. S2 was varied from 0.1 to 10 sec with an increment of 0.1 sec, and both h2 and hd were varied from 0.01 to 1.0 sec with an increment of 0.01 sec. It was found that the SR and MT were increased by up to 9.7% and 0.497 sec comparing with the previously published case when the values of S2, h2 and hd were set to 4.5, 0.3 and 0.2 sec, respectively. Also the results of sensitivity analysis showed that S2 and h2 had considerable influence on the SR while these variables were not so sensitive to the MT.

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References

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