Figure 1
Experimental procedure and data analysis.
Figure 2
The five attachment positions of ActiGraph GT9X Link. i) On the dominant wrist: attached with the help of the link wristband. ii) On the non-dominant wrist: attached with the help of the link wristband. iii) On the chest: attached with the aid of a pouch and belt. iv) On the hip on the contralateral side of the dominant wrist: attached with the aid of a link belt clip. v) On the thigh on the contralateral side of the dominant wrist: attached with the aid of a pouch and belt.
Table 1
Evaluation results. Emboldened values represent F-values of 0.9 or higher.
| PRECISION | RECALL | F-VALUE | ||
|---|---|---|---|---|
| Lying in the supine position | d-wrist | 0.9668 | 0.9791 | 0.9689 |
| nd-wrist | 0.9446 | 0.9737 | 0.9552 | |
| Chest | 0.9956 | 1.0000 | 0.9976 | |
| Hip | 0.9810 | 1.0000 | 0.9877 | |
| Thigh | 0.7483 | 0.7925 | 0.7445 | |
| All positions | 1.0000 | 1.0000 | 1.0000 | |
| Standing | d-wrist | 0.9548 | 0.9897 | 0.9662 |
| nd-wrist | 0.9350 | 0.9459 | 0.9306 | |
| Chest | 0.8528 | 0.8675 | 0.8094 | |
| Hip | 0.7305 | 0.7256 | 0.6920 | |
| Thigh | 0.9220 | 0.8741 | 0.8692 | |
| All positions | 0.9585 | 0.9949 | 0.9714 | |
| Sitting | d-wrist | 0.9137 | 0.8699 | 0.8728 |
| nd-wrist | 0.9171 | 0.8690 | 0.8769 | |
| Chest | 0.8119 | 0.7667 | 0.7591 | |
| Hip | 0.7232 | 0.7897 | 0.7336 | |
| Thigh | 0.7028 | 0.7103 | 0.6749 | |
| All positions | 0.9592 | 0.9615 | 0.9602 | |
| Taking a meal | d-wrist | 0.8616 | 0.8677 | 0.8584 |
| nd-wrist | 0.8650 | 0.9068 | 0.8712 | |
| Chest | 0.8442 | 0.8161 | 0.8187 | |
| Hip | 0.7119 | 0.6971 | 0.6669 | |
| Thigh | 0.8448 | 0.8340 | 0.8213 | |
| All positions | 0.9555 | 0.9393 | 0.9363 | |
| Brushing teeth | d-wrist | 0.9214 | 0.9051 | 0.9112 |
| nd-wrist | 0.8433 | 0.7979 | 0.8104 | |
| Chest | 0.9386 | 0.9171 | 0.9224 | |
| Hip | 0.8180 | 0.7944 | 0.7775 | |
| Thigh | 0.7347 | 0.7863 | 0.7457 | |
| All positions | 0.9471 | 0.9333 | 0.9372 | |
| Using the restroom | d-wrist | 0.7916 | 0.8806 | 0.8228 |
| nd-wrist | 0.7904 | 0.7634 | 0.7588 | |
| Chest | 0.8567 | 0.8569 | 0.8420 | |
| Hip | 0.8094 | 0.7224 | 0.7223 | |
| Thigh | 0.8620 | 0.8057 | 0.8146 | |
| All positions | 0.9529 | 0.9245 | 0.9309 | |
| Walking | d-wrist | 0.8964 | 0.9239 | 0.9064 |
| nd-wrist | 0.9295 | 0.9010 | 0.9039 | |
| Chest | 0.9761 | 0.9593 | 0.9661 | |
| Hip | 0.9328 | 0.9249 | 0.9205 | |
| Thigh | 0.9047 | 0.8652 | 0.8769 | |
| All positions | 0.9860 | 0.9636 | 0.9737 | |
| Ascending/descending the stairs | d-wrist | 0.9203 | 0.8957 | 0.8983 |
| nd-wrist | 0.8979 | 0.8920 | 0.8890 | |
| Chest | 0.9532 | 0.9785 | 0.9641 | |
| Hip | 0.9382 | 0.9294 | 0.9310 | |
| Thigh | 0.8855 | 0.9353 | 0.8990 | |
| All positions | 0.9632 | 0.9901 | 0.9756 | |
| Running | d-wrist | 1.0000 | 0.9974 | 0.9987 |
| nd-wrist | 0.9974 | 0.9897 | 0.9926 | |
| Chest | 1.0000 | 0.9889 | 0.9933 | |
| Hip | 0.9976 | 0.9923 | 0.9944 | |
| Thigh | 0.9797 | 0.9949 | 0.9855 | |
| All positions | 1.0000 | 1.0000 | 1.0000 | |
| Other movements | d-wrist | 0.7806 | 0.6952 | 0.7224 |
| nd-wrist | 0.7316 | 0.7423 | 0.7192 | |
| Chest | 0.7917 | 0.7777 | 0.7739 | |
| Hip | 0.7929 | 0.7600 | 0.7336 | |
| Thigh | 0.7719 | 0.7274 | 0.7280 | |
| All positions | 0.8777 | 0.8837 | 0.8704 |
Figure 3
Confusion matrices comparing predicted and correct activities. The rows correspond to the actual activities, whereas the columns correspond to the activities predicted by the activity classifier. (a) Non-dominant wrist classifier. The light blue underline indicates misclassification between taking a meal and other movements. The orange underline indicates misclassification between using the restroom and other movements. The red underline indicates misclassification between walking and ascending/descending the stairs. The purple underline indicates misclassification among brushing teeth, standing, and taking a meal. (b) Chest classifier. The light blue underline indicates misclassification between taking a meal and using the restroom. The orange underline indicates misclassification between using the restroom and other movements. The green underline indicates misclassification between standing and sitting. (c) Hip classifier. The light blue underline indicates misclassification among taking a meal, sitting, and using the restroom. The green underline indicates misclassification between standing and sitting. (d) Thigh classifier. The blue underline indicates misclassification between lying in the supine position and sitting.
Figure 4
Example of waveform data along the x axis. The red and green lines correspond to the data of the non-dominant wrist and chest data, respectively. The numbers represent the activities: 0, lying in a supine position; 1, standing; 2, sitting; 3, taking a meal; 9, other movements; 4, brushing teeth; 5, using the restroom; 6, walking; 7, ascending/descending the stairs; 8, running. (a) acceleration along the x-axis. (b) angular velocity along the x-axis. (c) magnetic field strength along the x-axis.
Figure 5
Example of waveform data along the y axis. The red and green lines correspond to the data of the non-dominant wrist and chest data, respectively. The numbers represent the activities: 0, lying in a supine position; 1, standing; 2, sitting; 3, taking a meal; 9, other movements; 4, brushing teeth; 5, using the restroom; 6, walking; 7, ascending/descending the stairs; 8, running. (a) acceleration along the y-axis. (b) angular velocity along the y-axis. (c) magnetic field strength along the y-axis.
Figure 6
Example of waveform data along the z axis. The red and green lines correspond to the data of the non-dominant wrist and chest data, respectively. The numbers represent the activities: 0, lying in a supine position; 1, standing; 2, sitting; 3, taking a meal; 9, other movements; 4, brushing teeth; 5, using the restroom; 6, walking; 7, ascending/descending the stairs; 8, running. (a) acceleration along the z-axis. (b) angular velocity along the z-axis. (c) magnetic field strength along the z-axis.