摘要
Force platforms (FPs) are used in human movement analysis to measure the ground reaction force and the center of pressure (COP), and calculate derived kinetic and energetic quantities.
We propose a re-calibration method that compensates for the FP non-linearity induced by top plate bending under loading. The method develops a previous solution that was proposed for a linear re-calibration and proved suitable for both local and global error compensation (Cedraro et al., 2008). The new method was experimentally tested on 4 commercial FPs by estimating the non-linear re-calibration matrix in a first training trial and by using it to assess the three force components and the COP in a validation trial, comparing the new method to the previously proposed solution for global, linear re-calibration.
The average COP accuracy (mm) in the training trial was (mean +/- std): 2.3 +/- 1.4, 2.6 +/- 1.5, 11.8 +/- 4.3, 14.0 +/- 2.5 for the 4 FPs before re-calibration, and 0.7 +/- 0.4, 0.6 +/- 0.2, 0.5 +/- 0.2, 2.3 +/- 1.3 after non-linear re-calibration. In the validation trial, for one of the 4 tested FPs, mean errors for the three force components (N) and COP (mm) were: 3.6 +/- 2.3 (F(X)), 3.0 +/- 0.7 (F(Y)), 5.0 +/- 2.5 (F(Z)), 1.2 +/- 0.68 (COP) after linear re-calibration, and 2.5 +/- 0.7 (F(X)), 2.6 +/- 0.5 (F(Y)), 3.9 +/- 1.2 (F(Z)), 0.6 +/- 0.3 (COP) after non-linear re-calibration.
The proposed global, non-linear method performed equally well as the local, linear re-calibration method, proving well-suited to compensate for the mild non-linear behavior of FP with the advantage of estimating a single re-calibration matrix.
- 出版日期2011-4