| Abstract |
By extracting features from the trajectory of center of pressure (COP), many
features have been proposed to quantify the stability of postural balance. However, most
of these studies focus on the total COP (COP T ) which is the weighted sum of the COP
of the right foot (COP R ) and COP of the left foot (COP L ). In contrast, very little attention
has been given to the coordination patterns between COP T , COP R and COP L .
To investigate the impacts of the correlation patterns of these three COPs on
balance, this study uses twelve correlation coefficients to characterize the coupling
strengths among COP T , COP R and COP L . The efficacies of these correlation
coefficients in assessing postural stability are tested by two different methods. The first
method compares the sample means of these correlation coefficients of the eyes open
and eyes closed conditions. Experimental results show that six of the tested twelve
correlation coefficients exhibit statistically significant differences.
The second method investigates the associations between the tested correlation
coefficients and nine COP velocity features. For every pair of the tested correlation
coefficient and tested COP velocity feature, the second method compares the sample
means of the COP velocity feature of the time period when the tested correlation
coefficient is positive to that of the time period when the tested correlation coefficient
is negative. Since many of such test results are statistically significant, it is believed the
ratio of time that COP T , COP R and COP L are positively correlated can be used to assess
postural stability.
Keywords: center of pressure, coordination patterns, correlation coefficient, postural
stability. |
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