Institute of Fundamental Technological Research

Driving on uneven roads causes vibrations of the vehicle. Modern smartphones are equipped with accelerometers and gyroscopes which allow for inexpensive acquisition of information about the shaking level. This study reports on field tests of a system, which measures vibrations of a driving vehicle using four smartphones as sensors. The collected data undergo a series of processing steps, namely synchronization, virtual reorientation, temporal and spectral filtering, and assignment of road localization. We use quarter-car and half-car suspension models to retrieve the longitudinal road profile and to compute unevenness indicators. The accuracy of the system was computed by comparison with traditional laser profilometer on an 18.6 km long test section using eight rides with different speeds. It averages to 71% and exceeds 80% for the best calibrated cases. Additionally, we report on the feedback obtained during tests of the system in a district road administration in Poland.