Use of Phone Sensors to Enhance Distracted Pedestrians' Safety.

Studies have shown that using smartphones while walking-called distracted walking-significantly increases the risk of pedestrians colliding with dangerous objects. In this paper, we explore how to mitigate this problem by exploiting the phone's built-in sensors only and developing an application called BumpAlert. BumpAlert provides a generic solution without requiring any prior knowledge of the user's surroundings by estimating distances to nearby objects using the phone's speakers and microphones. This process is enhanced further by using the images acquired from the phone's rear camera, when necessary. We have evaluated BumpAlert under a variety of settings ranging from aisle to outdoor environments with walls, pillars, signboards, dustbins, and people, etc., that are common in our daily surroundings. Our evaluation has shown an average accuracy of BumpAlert to be higher than 95 percent with a less than 2 percent false-positive rate to detect frontal objects 2-4m away, which suffices for the user to react and avoid collision. Even though BumpAlert is unable to detect all dangerous situations, most participants of our user study feel safer when they walk with BumpAlert enabled. Integrating our current design of BumpAlert with other safety systems can provide a practical solution for protecting distracted pedestrians.