Application of a Smart Phone’s Built-In Barometer Sensor for Indoor Localization

Abstract

The goal of our research was to determine if the built-in smart phone barometer sensor could be applied to indoor localization for determining which floor a person is on in a multi-story building. Since the barometer sensor reads pressure, and pressure changes based on elevation, our idea was that the readings should change drastically enough per floor to be able to determine which floor a person is on in a building. To achieve our goal, we created an android mobile app that saves raw data from the barometer sensor into a csv file, allowing for comparison between floor values later. To collect data, we used two different android phones and collected a large data set on three different floors in the same stairwell of a building. Then, we looked at the differences between each floor to see if the amounts were drastic enough for values to be unique to each floor. We observed the difference between consecutive floors to be 0.3 and 0.5 (hPa), which is a large enough difference to identify a floor. However, the two smart phones had data that differed by 5 hPa, and the base readings of each phone would vary by 12 hPa on different days. However, the actual difference between the floors was always between 0.3 and 0.5 (hPa). Therefore, the barometer can be used to determine which floor a smart phone, and thus a person is on. Future research needs to be done to determine the direct relationship of temperature and pressure readings, since pressure increases as temperature increases.