Chinese Journal of Tissue Engineering Research ›› 2019, Vol. 23 ›› Issue (34): 5473-5478.doi: 10.3969/j.issn.2095-4344.1954

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Motion compatibility recognition of walk-aid robot based on multi-scale permutation entropy

Chen Lingling, Yang Zekun, Sun Jianjun, Zhang Cun
  

  1. School of Artificial Intelligence and Data Science, Hebei University of Technology, Tianjin 300130, China
  • Received:2019-05-30 Online:2019-12-08 Published:2019-12-08
  • Contact: Yang Zekun, Master, School of Artificial Intelligence and Data Science, Hebei University of Technology, Tianjin 300130, China
  • About author:Chen Lingling, MD, Associate profressor, School of Artificial Intelligence and Data Science, Hebei University of Technology, Tianjin 300130, China
  • Supported by:

    the National Natural Science Foundation of China, No. 61703135 (to CLL); the Natural Science Foundation of Hebei Province, No. F2017202119 (to CLL)

Abstract:

BACKGROUND: At present, the number of older adults with impaired limb motor ability continues to increase due to the influence of the environment or the deterioration of bodily functions. The decline of the lower limbs' motor ability of the older adults has made the design and development of walk-aid robot become one of current social care focus.
OBJECTIVE: When the motion trajectory of walk-aid robot is inconsistent with the desired trajectory of the human, the adaptive adjustment of walk-aid robot should be realized. This study was to recognize three kinds of situations, such as too large stride, too small stride and appropriate stride.
METHODS: In view of the nonlinearity and strong noise of surface electromyography, a multi-scale permutation entropy method based on wavelet decomposition was proposed to recognize three situations of man-robot’s motion compatibility. First, wavelet decomposition of collected surface electromyography signal was performed. Then, the permutation entropy was calculated for each scale of surface electromyography. Finally, Gaussian kernel support vector machine was used for pattern recognition.
RESULTS AND CONCLUSION: After wavelet decomposition, the signal on the d5 scale could be better recognized. Among them, recognition rate was 92% for too large stride, 90% for too small stride, and 94% for appropriate stride. The average recognition rate was 92%, which was 4.67% higher than that of original surface electromyography. Wavelet decomposition also achieved better results than other commonly used multi-scale methods. Therefore, in the man-machine motion compatibility recognition, the surface electromyography signal can be decomposed by wavelet to extract the permutation entropy on each scale, which can help to increase the recognition accuracy.

Key words: surface electromyography, walk-aid robot, motion compatibility, pattern recognition, wavelet decomposition, multi-scale, permutation entropy, Gaussian kernel support vector machine

CLC Number: