BaroDepth: A Method of Estimating Depth with Barometric Pressure Sensors in Smartphones

Underwater activities are enjoyed around the world. Divers wear dive computers that allow visualization of diving information including depth and dive time, to avoid the risk of decompression sickness. However, dive computers are so expensive that they burden novice divers. A method of estimating water depth with barometric pressure sensors in smartphones, instead of dive computers, was studied [3]. Unfortunately, the conventional method [3] for estimating water depth using a barometric pressure sensor in a smartphone is limited to estimating shallow depths of about 1 m to 2 m due to the sensor only being able to detect up to about 1100 hPa to 1200 hPa. We propose a method of estimating water depths of several tens of meters with a barometric pressure sensor in a smartphone by adopting a waterproof hard case with a decompression adjustment function and a polynomial regression model. We implemented a prototype of the proposed method and conducted experiments to evaluate the precision of estimating water depths down to 20 m in the sea. The experiments revealed that the proposed method could cover water from 0 to 20 m depths and estimate water depths with a root mean squared error (RMSE) of less than 1 m.