As part of a research project, I have been tasked with determining gait speed (walking speed) for a subject using a handheld iPhone. The main constraint is that walking distances are very short (10-30 meters), and accuracy is critical (data is used for research.) Using a pedometer and measuring step distance is not an option (too time consuming.) The only plausible way I foresee this could be work is using accelerometer data. However, I'm not sure whether this will succeed. I was wondering if anyone has experience with these sensors and could answer the following two questions:
- Will an iPhone accelerometer plausibly be able to accurately measure walking distance for such short distances? Are there any figures on accelerometer accuracy for this kind of sensor? (I couldn't find any.)
- Are there any established protocols for converting accelerometer data into distance measurements (calibration, noise correction, sampling rates, etc.) that have been shown to have good accuracy for such short distances? I have been able to find this, http://www.freescale.com/files/sensors/doc/app_note/AN3397.pdf but I'm not sure if this will apply well to the iPhone sensors.