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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