Table 1
Practical challenges and how WEARDA addresses them.
| CHALLENGES | PREPARATION | MEASUREMENT | LOGISTICS | PRIVACY | REPRODUCIBILITY |
|---|---|---|---|---|---|
| Configuration file 1 | v | v | |||
| Watch identifier 2 | v | v | v | v | |
| Automatic correction of configuration file 3 | v | v | |||
| Removal of files by UI watch 4 | v | v | v | ||
| Not easy to remove file by UI watch 5 | v | v | |||
| Person identifier 6 | v | v | v | ||
| Storage of all sensor data 7 | v | ||||
| Easy to enter person identifier 8 | v | ||||
| Data storage for multiple days 9 | v | v | |||
| Hard to inadvertently stop data collection 10 | v | ||||
| Use of stand-alone laptop 11 | v | v | v | ||
| Quick upload of files to laptop 12 | v | v | |||
| Wireless upload to laptop 13 | v | v | |||
| Person id, date, time, and watch id in data filename 14 | v | v | |||
| Stop measurement only with shutdown 15 | v | ||||
| Metadata in first line of files 16 | v | ||||
| Copy of used configuration file 17 | v | ||||
| Label private data 18 | v | ||||
| Change configuration file while measuring 19 | v |
Figure 1
Left: the icon of the sensor application in the Tizen OS menu, right the sensor application with the person-id spinner, restart, and clean button.
Figure 2
State diagram of sensor application (green), sensor service (orange), and the Tizen OS (grey).
Figure 3
Watch spinning on its glass, decelerating. The oscillation is caused by the movements of the arms of the band. The graph shows the gravity acceleration per axis in m/s2.
Figure 4
Watch spinning on its glass, decelerating. The oscillation is caused by the movements of the arms of the band. The graph shows the linear acceleration per axis in m/s2.
Figure 5
Watch spinning on its glass, decelerating. The oscillation is caused by the movements of the arms of the band. The graph shows the rotation velocity per axis in degrees per second.
Table 3
Sample density as a function of write- and sensor readout interval in milliseconds.
| SAMPLE RATE | SENSOR INTERVAL | WRITER INTERVAL | SAMPLE DENSITY GPS OFF | SAMPLE DENSITY GPS ON |
|---|---|---|---|---|
| 50 Hz | 10 ms | 20 ms | 0.99 | 0.90–0.93 |
| 50 Hz | 20 ms | 10 ms | 0.94 | |
| 40 Hz | 25 ms | 25 ms | 0.80–0.87 | 0.975 |
| 40 Hz | 10 ms | 25 ms | 0.86 | |
| 40 Hz | 15 ms | 25 ms | 0.94 | |
| 30 Hz | 15 ms | 33 ms | 0.96 | |
| 30 Hz | 33 ms | 33 ms | 0.97 | |
| 25 Hz | 20 ms | 40 ms | 0.99 | |
| 20 Hz | 10 ms | 50 ms | 0.96 | |
| 20 Hz | 25 ms | 50 ms | 0.98 | |
| 20 Hz | 50 ms | 50 ms | 0.93 | |
| 10 Hz | 100 ms | 100 ms | 0.99 |
Table 2
Configuration settings.
| FIELD NAME | FIELD TYPE | POSSIBLE VALUES, () = DEFAULT |
|---|---|---|
| Unique identifier watch | string | Example "D8F8" |
| Accelerometer interval | integer | 0 indicates switched off, 10–1000 (25) ms |
| Linear accelerometer interval | integer | 0 indicates switched off, 10–1000 (25) ms |
| Gyroscope interval | integer | 0 indicates switched off, 10–1000 (25) ms |
| Barometer interval | integer | 0 indicates switched off, 10–1000 (100) ms |
| GPS interval | integer | 1–10 (1) seconds |
| GPS middle point privacy circle, latitude | float | –90.0–90.0 (52.169311) degrees |
| GPS middle point privacy circle, longitude | float | –180.0–180.0 (4.456711) degrees |
| GPS radius privacy circle | integer | 0 indicates switched off, 10–1000 (100) meter |
| Write recordings interval | float | 0.01–10.0 (0.05) seconds |