Table 2.
RMSE of the accelerations obtained from the optical system through the EKF-based method with different combinations of process noise standard deviations and cutoff frequencies, with respect to the accelerations measured by the IMUs, taken as reference. The row with the lowest mean RMSE is highlighted in red.
| Acc. Std. (m/s2 or rad/s2) | Cutoff Freq. (Hz) | RMSE (m/s2) | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Pelvis | R Thigh | L Thigh | R Tibia | L Tibia | R Foot | L Foot | Mean | ||
| 0.1 | 6 | 0.717 | 1.047 | 1.195 | 1.663 | 1.624 | 2.649 | 2.430 | 1.618 |
| 0.1 | 10 | 0.679 | 1.020 | 1.155 | 1.679 | 1.618 | 2.530 | 2.338 | 1.377 |
| 0.1 | 15 | 0.676 | 1.018 | 1.136 | 1.678 | 1.614 | 2.433 | 2.274 | 1.354 |
| 0.1 | 20 | 0.682 | 1.022 | 1.133 | 1.674 | 1.611 | 2.377 | 2.229 | 1.341 |
| 0.1 | 25 | 0.690 | 1.028 | 1.135 | 1.672 | 1.612 | 2.341 | 2.198 | 1.335 |
| 0.1 | 30 | 0.698 | 1.035 | 1.140 | 1.672 | 1.615 | 2.318 | 2.176 | 1.332 |
| 0.5 | 6 | 0.606 | 1.011 | 1.108 | 1.513 | 1.442 | 2.553 | 2.274 | 1.313 |
| 0.5 | 10 | 0.545 | 0.969 | 1.030 | 1.514 | 1.412 | 2.340 | 2.105 | 1.239 |
| 0.5 | 15 | 0.557 | 0.965 | 1.017 | 1.524 | 1.415 | 2.183 | 2.004 | 1.208 |
| 0.5 | 20 | 0.582 | 0.977 | 1.034 | 1.530 | 1.424 | 2.098 | 1.943 | 1.198 |
| 0.5 | 25 | 0.608 | 0.996 | 1.058 | 1.538 | 1.439 | 2.049 | 1.907 | 1.199 |
| 0.5 | 30 | 0.634 | 1.018 | 1.083 | 1.553 | 1.458 | 2.018 | 1.887 | 1.207 |
| 1 | 6 | 0.604 | 1.006 | 1.099 | 1.484 | 1.433 | 2.565 | 2.267 | 1.307 |
| 1 | 10 | 0.538 | 0.963 | 1.026 | 1.454 | 1.383 | 2.330 | 2.072 | 1.221 |
| 1 | 15 | 0.562 | 0.961 | 1.033 | 1.457 | 1.379 | 2.161 | 1.955 | 1.188 |
| 1 | 20 | 0.601 | 0.978 | 1.067 | 1.466 | 1.393 | 2.074 | 1.890 | 1.183 |
| 1 | 25 | 0.639 | 1.004 | 1.105 | 1.483 | 1.417 | 2.026 | 1.857 | 1.191 |
| 1 | 30 | 0.679 | 1.036 | 1.143 | 1.511 | 1.446 | 1.999 | 1.843 | 1.207 |
| 10 | 6 | 0.632 | 0.987 | 1.132 | 1.473 | 1.439 | 2.580 | 2.324 | 1.321 |
| 10 | 10 | 0.576 | 0.926 | 1.086 | 1.393 | 1.343 | 2.344 | 2.131 | 1.225 |
| 10 | 15 | 0.606 | 0.928 | 1.115 | 1.374 | 1.300 | 2.174 | 2.002 | 1.187 |
| 10 | 20 | 0.665 | 0.973 | 1.168 | 1.397 | 1.307 | 2.084 | 1.934 | 1.191 |
| 10 | 25 | 0.739 | 1.041 | 1.228 | 1.452 | 1.342 | 2.037 | 1.909 | 1.218 |
| 10 | 30 | 0.823 | 1.124 | 1.292 | 1.538 | 1.391 | 2.014 | 1.913 | 1.262 |
| 50 | 6 | 0.633 | 0.989 | 1.134 | 1.478 | 1.442 | 2.578 | 2.330 | 1.323 |
| 50 | 10 | 0.574 | 0.933 | 1.088 | 1.401 | 1.348 | 2.343 | 2.142 | 1.229 |
| 50 | 15 | 0.603 | 0.943 | 1.119 | 1.386 | 1.307 | 2.177 | 2.018 | 1.194 |
| 50 | 20 | 0.666 | 1.000 | 1.179 | 1.424 | 1.319 | 2.091 | 1.955 | 1.204 |
| 50 | 25 | 0.753 | 1.085 | 1.253 | 1.507 | 1.359 | 2.047 | 1.937 | 1.243 |
| 50 | 30 | 0.859 | 1.190 | 1.336 | 1.632 | 1.416 | 2.032 | 1.953 | 1.302 |