Activity Level Estimator on a Commercial Mobile Phone: A Feasability Study

On a growing scale, we use mobile phones for diverse activities in our daily life, for example for entertainment, information or education purposes. In our present research, we assess the feasibility of using a mobile phone to unobtrusively track its user physical activity and the resulting energy expenditure; without of use of any dedicated external device. Activity Level Estimator (ALE) is an application developed for Android mobile phone which uses the built-in sensors. ALE analyzes and calculates how much time the user spends per activity level and gives estimation of his or her energy expenditure. ALE is designed to be operational as an unobtrusive, continuous real-time background application for a long-terms trend and behavioral studies in elderly care. ALE was tested with a set of users wearing the mobile phone in their pocket. Via an extensive user tests, we assessed the accuracy of ALE against a dedicated BodyMedia Sensewear device. We conclude that ALE is accurate on average 86% for different levels of walking, and it underestimates user’s energy expenditure of 23% during a period of 24 hours.