Table 2. Body worn sensor errors for estimating 3D body segment angles (peak and range of motion) during fast, medium, and slow speed movements.
Motion |
Anterior-Posterior |
Medial-lateral |
Internal-external |
Type of Error |
Peak |
Range |
Peak |
Range |
Peak |
Range |
Abs* [°] |
Re** [%] |
Abs [°] |
Re [%] |
Abs [°] |
Re [%] |
Abs [°] |
Re [%] |
Abs [°] |
Re [%] |
Abs [°] |
Re [%] |
Fast Movement |
Systematic |
-1.37 |
-1.80 |
.51 |
.66 |
-.27 |
-.33 |
.07 |
.10 |
4.76 |
2.97 |
-2.07 |
-1.29 |
Random |
1.90 |
2.47 |
3.70 |
4.80 |
.92 |
1.82 |
1.65 |
3.27 |
5.32 |
3.35 |
9.12 |
5.76 |
RMSE† |
2.21 |
2.88 |
3.35 |
4.35 |
1.42 |
2.84 |
1.50 |
2.98 |
6.81 |
4.26 |
8.43 |
5.32 |
Normal Movement |
Systematic |
-2.16 |
-2.55 |
.60 |
.71 |
-1.15 |
-2.46 |
.33 |
.70 |
2.56 |
1.83 |
-.83 |
-.59 |
Random |
1.46 |
1.80 |
3.09 |
3.79 |
.76 |
1.73 |
1.48 |
3.32 |
2.09 |
1.47 |
3.85 |
2.72 |
RMSE† |
2.57 |
3.07 |
2.83 |
3.47 |
1.45 |
3.23 |
1.37 |
3.08 |
3.20 |
2.27 |
3.55 |
2.50 |
Slow Movement |
Systematic |
-.93 |
-1.16 |
.28 |
.36 |
-1.25 |
-2.77 |
.30 |
.67 |
-.99 |
-.66 |
.27 |
.20 |
Random |
1.04 |
1.32 |
2.07 |
2.62 |
.71 |
1.67 |
1.52 |
3.54 |
1.34 |
.93 |
2.26 |
1.59 |
RMSE† |
1.41 |
1.78 |
1.88 |
2.37 |
1.45 |
3.27 |
1.40 |
3.25 |
1.58 |
1.07 |
2.05 |
1.43 |
* Absolute error value;† Relative error value;‡ Root mean square error