Aduayom-Ahego, Akouetevi

Ehara, Yoshihiro

Inoue, Shota

Niigata Regional Repository

－ 71 －
第17回 新潟医療福祉学会学術集会
New calibration method of centre of 
pressure of force platform 
 
 
Akouetevi Aduayom-Ahego, Yoshihiro Ehara, Shota Inoue 
Graduate School of Health and Welfare, Niigata University of 
Health and Welfare 
 
【Introduction】 
Kinetics and kinematics data are measured using force platforms 
in the gait analysis laboratory. Reducing errors related to the 
force platform when collecting data is necessary. Joint moments 
will be affected if there is error in the system. Valid results of the 
joint moments can only be obtained if the determination of the 
Centre of Pressure (COP) is accurate. To calibrate the force 
platforms, heavy devices have been used. However these devices 
might be difficult to move during the data collections. The 
purpose of the present study is to calibrate the location of the 
Centre of Pressure with commonly used force platforms in the 
gait laboratories. 
 
【Materials and Methods】 
The new calibration device is consisted of a bar of approximately 
1m long and 35mm diameter fixed on the top of the wooden 
sandal. A metallic ball point of 20mm diameter was attached to 
the sole of the wooden sandal. Three markers set on the device 
then a male subject was asked to put one leg on the sandal and 
he was ordered to put his weight vertically on many places of the 
two force platforms (Fig. 1). A computational program was 
developed using Matlab to calculate the position of the centre of 
pressure before and after the calibration. 
 
【Results】 
Figures 2 and 3 show the position of COPV and COPf  data 
before and after calibration of the two force platforms. Before 
the calibration, the maximum difference between COPv and 
COPf was 22.2 mm and 24.6mm respectively for the two force 
platforms. And after calibration the maximum difference was 
reduced to 2.5 mm and 2.7 mm respectively. 
 
【Discussion】 
The method highlighted in this study allows to calculate and 
correct the position of the COP data. This calibration method will 
reduce systematic error related to COP when collecting kinetics 
and kinematics data. 
 
【Conclusion】 
The method used in this study allows to reduce the maximum 
error from 24.6 mm to 2.7 mm. The device described in this 
paper is composed of a common wooden sandal especially used 
when wearing Japanese traditional wear kimono. It is then light 
weighted device less than 0.5 kg, portable and can be used to 
calibrate the gait analysis laboratory force platforms. 
 
 
Fig. 1. Subject applying weight vertically on the force platform 
 
Fig. 2. Position of COPv and COPf  data of the force plate 1 after 
calibration.  
(COPv=COP taken from VICON, COPf= COP taken from the 
force platform) 
 
 
  
Fig. 3. Position of COPv and COPf  data of the force plate 2 after 
calibration.  
(COPv=COP taken from VICON, COPf= COP taken from the 
force platform) 
P−51


New calibration method of centre of pressure of force platform

http://nirr.lib.niigata-u.ac.jp/bitstream/10623/73759/1/071_w1701.pdf

New calibration method of centre of pressure of force platform

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