Figure 1
Example of acceleration data. The red and blue lines correspond to the wrist and hip data, respectively. The alphabets indicate the activities; a: changing clothes. b: sitting. c: standing. d: lying in a supine position. e: other movements. f: moving luggage. g: brushing teeth. h: going up/down the stairs. i: walking. j: running. (a) acceleration along the horizontal axis. (b) acceleration along the vertical axis. (c) acceleration along the lateral axis. Green squares indicate activities that are suitably recognized (F > 0.9). Silver squares indicate activities that are not recognized (F < 0.7). Gold squares indicate activities that are not recognized by the hip classifier but are recognized by the wrist classifier.
Table 1
Evaluation results. Emboldened values represent F-values of 0.7 or higher.
| PRECISION | RECALL | F-VALUE | ||
|---|---|---|---|---|
| Changing clothes | wrist+hip | 0.8588 | 0.7858 | 0.7897 |
| wrist | 0.7698 | 0.7165 | 0.7124 | |
| hip | 0.7202 | 0.4874 | 0.5509 | |
| Sitting | wrist+hip | 0.5923 | 0.5504 | 0.5192 |
| wrist | 0.5141 | 0.4157 | 0.4092 | |
| hip | 0.4606 | 0.4407 | 0.4171 | |
| Standing | wrist+hip | 0.7667 | 0.8088 | 0.7663 |
| wrist | 0.7311 | 0.7608 | 0.7229 | |
| hip | 0.5150 | 0.5030 | 0.4601 | |
| Lying in supine position | wrist+hip | 0.9977 | 0.9978 | 0.9977 |
| wrist | 0.8256 | 0.7374 | 0.7301 | |
| hip | 0.9957 | 0.9978 | 0.9966 | |
| Brushing teeth | wrist+hip | 0.9278 | 0.8415 | 0.8635 |
| wrist | 0.8324 | 0.8124 | 0.8090 | |
| hip | 0.6780 | 0.5645 | 0.5823 | |
| Moving luggage | wrist+hip | 0.8769 | 0.8972 | 0.8799 |
| wrist | 0.8335 | 0.8571 | 0.8397 | |
| hip | 0.7288 | 0.7933 | 0.7448 | |
| Going up/down stairs | wrist+hip | 0.9104 | 0.8405 | 0.8486 |
| wrist | 0.8023 | 0.7363 | 0.7281 | |
| hip | 0.8663 | 0.8216 | 0.8169 | |
| Walking | wrist+hip | 0.8857 | 0.9132 | 0.8922 |
| wrist | 0.7981 | 0.7756 | 0.7621 | |
| hip | 0.8948 | 0.8914 | 0.8828 | |
| Running | wrist+hip | 1.0000 | 0.9851 | 0.9923 |
| wrist | 0.9904 | 0.9777 | 0.9834 | |
| hip | 0.9786 | 0.9628 | 0.9682 | |
| Other movements | wrist+hip | 0.6322 | 0.6985 | 0.6245 |
| wrist | 0.5436 | 0.6506 | 0.5630 | |
| hip | 0.5127 | 0.6093 | 0.5289 |
Figure 2
Confusion matrix: wrist+hip, wrist, and hip classifiers. The rows show the actual activities, while the columns show the activities predicted by the activity classifiers. The green underline indicates misclassification between sitting and other movements. The orange underline indicates misclassification between lying in a supine position and sitting, standing, or other movements. The red underline indicates misclassification between going up/down the stairs and walking. The purple underline indicates misclassification between changing clothes and moving luggage. Light blue underline indicates misclassification between sitting and standing.