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Table 2 Full feature set used for training the classification models

From: Predicting reactive stepping in response to perturbations by using a classification approach

Feature Description Norm. Mean SD  
   factor \(\bar {x}\) σ  
xcom Position of the CoM in x-direction (anteroposterior) 1/hcom 0.056 0.030  
com Velocity of the CoM in x-direction 1/hcom 0.000 0.057 1/s
com Acceleration of the CoM in x-direction   0.001 0.388 m/s2
kcom Whole body angular momentum around the CoM \(1/(Mh_{com}^{2})\) 0.000 0.012 rad/s
xcop Position of the CoP in x-direction 1/lfoot 0.233 0.161  
cop Velocity of the CoP in x-direction 1/lfoot 0.000 0.578 1/s
cop Acceleration of the CoP in x-direction   0.000 2.090 m/s2
ycop Position of the CoP in y-direction (mediolateral) 1/wstance 0.009 0.047  
cop Velocity of the CoP in y-direction 1/wstance -0.001 0.185 1/s
ÿcop Acceleration of the CoP in y-direction   -0.003 1.308 m/s2
θhip Mean joint angle of left and right hip   0.002 0.075 rad
θknee Mean joint angle of left and right knee   0.090 0.085 rad
xCJC Position of the cervical joint center in x-direction 1/H 0.035 0.028  
xhip Mean position of the left and right hip in x-direction 1/H 0.035 0.016  
xknee Mean position of the left and right knee in x-direction 1/H 0.029 0.013  
  1. Figure 4 shows the features and normalization factors. All positions are expressed with respect to the mean position of the left and right ankle over the two seconds before the perturbation. For the kinematics feature set the CoP-based features were dismissed