Assessment of Distance Measurement with Selected Wearable Devices in Telemonitoring

The use of wearable devices in health applications is not only being utilized in illness, it is also a major area of interest in fitness. Wearable devices for fitness tracking are available to consumers and can measure and calculate important fitness data trends based on movement and physiological parameters. Accelerometers are the sensors that provide information on the movement parameters of step count and distance. It is understood to obtain a distance measurement, there must be information provided about the step-to-step length but these devices typically only measure step count, and do provide the step-to-step length. The step-to-step length is based on the user's height which is input into the settings, allowing for the calculation of the distance. The intention of this study is to introduce a preliminary experiment to evaluate two different devices -- the Fitbit Flex and the Polar Loop -- for distance measurement methods, based on the step-to-step length values determined from collected device data. One measurement method uses a default stride length while the other method uses a stride speed algorithm. The step-to-step values for each device were compared to an experimental ground truth value for accuracy, which was used as a pilot for comparing the initial device data. In this preliminary study, the default stride length method provided a more accurate method for measuring the distance. A subsequent study is expected to be performed with more participants and parameters, which will be more suitable for providing a better comparison between the two devices against a ground truth.