In order to evaluate the ability of human standing balance scientifically, we in this study proposed a new evaluation method based on the chaos nonlinear analysis theory. In this method, a sinusoidal acceleration stimulus in forward/backward direction was forced under the subjects' feet, which was supplied by a motion platform. In addition, three acceleration sensors, which were fixed to the shoulder, hip and knee of each subject, were applied to capture the balance adjustment dynamic data. Through reconstructing the system phase space, we calculated the largest Lyapunov exponent (LLE) of the dynamic data of subjects' different segments, then used the sum of the squares of the difference between each LLE (SSDLLE) as the balance capabilities evaluation index. Finally, 20 subjects' indexes were calculated, and compared with evaluation results of existing methods. The results showed that the SSDLLE were more in line with the subjects' performance during the experiment, and it could measure the body's balance ability to some extent. Moreover, the results also illustrated that balance level was determined by the coordinate ability of various joints, and there might be more balance control strategy in the process of maintaining balance.
Citation:
LIUKun, WANGHongrui, XIAOJinzhuang, ZHAOQing. A Standing Balance Evaluation Method Based on Largest Lyapunov Exponent. Journal of Biomedical Engineering, 2015, 32(6): 1212-1216. doi: 10.7507/1001-5515.20150215
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张春涛, 马千里, 彭宏, 等.基于条件熵扩维的多变量混沌时间序列相空间重构[J].物理学报, 2011, 60(2):112-119.
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BOCCALETTI S, VALLADARES D L, PECORA L M, et al. Reconstructing embedding spaces of coupled dynamical systems from multivariate data[J]. Phys Rev E Stat Nonlin Soft Matter Phys, 2002, 65(3 Pt 2A):035204.
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- 1. 纪树荣.实用偏瘫康复训练技术图解[M].第2版.北京:人民军医出版社, 2009:162-165.
- 2. 刘心东.混沌及其在生物医学工程中的应用[J].国外医学生物医学工程分册, 1993, 16(2):63-70.
- 3. YAMADA N. Chaotic swaying of the upright posture[J]. Hum Mov Sci, 1995, 14(6):711-726.
- 4. ACHARYA U R, GOH S C, ⅡJIMA K, et al. Analysis of body responses to an accelerating platform by the largest-Lyapunov-exponent method[J]. Proc Inst Mech Eng H, 2009, 223(H1):111-120.
- 5. PASCOLO P, BARAZZA F, CARNIEL R. Considerations on the application of the chaos paradigm to describe the postural sway[J]. Chaos Solitons Fractals, 2006, 27(5):1339-1346.
- 6. ALEXANDROV A V, FROLOV A A, MASSION J. Biomechanical analysis of movement strategies in human forward trunk bending.Ⅱ. Experimental study[J]. Biol Cybern, 2001, 84(6):435-443.
- 7. STERGIOU N, DECKER L M. Human movement variability, nonlinear dynamics, and pathology:is there a connection?[J]. Hum Mov Sci, 2011, 30(5):869-888.
- 8. TAKENS F. Detecting strange attractors in turbulence[M]. Berlin Heidelberg:Springer Berlin Heidelberg, 1981:366-381.
- 9. KIM H S, EYKHOLT R, SALAS J D. Nonlinear dynamics, delay times, and embedding Windows[J]. Physica D, 1999, 127(1-2):48-60.
- 10. WOLF A, SWIFT J B, SWINNEY H L, et al. Determining lyapunov exponents from a time series[J]. Physica D, 1985, 16(3):285-317.
- 11. 张春涛, 马千里, 彭宏, 等.基于条件熵扩维的多变量混沌时间序列相空间重构[J].物理学报, 2011, 60(2):112-119.
- 12. BOCCALETTI S, VALLADARES D L, PECORA L M, et al. Reconstructing embedding spaces of coupled dynamical systems from multivariate data[J]. Phys Rev E Stat Nonlin Soft Matter Phys, 2002, 65(3 Pt 2A):035204.