GNSS-free Online Calibration of Inertial Measurement Units in Road Vehicles

This paper presents a realtime recursive algorithm that can estimate, starting from an unknown pose, the mounting angles (roll, pitch and yaw) of an inertial sensor unit using accelerations and angular velocities. We analyze the use case of telematic boxes (E-Box) that are mounted on ground vehicles for safety reason (like E-call or automatic crash detection) or driving style monitoring. In order to work properly and record meaningful data, the box reference frame needs to be correctly aligned with the vehicle one. The proposed algorithm aligns the two reference frame online while the car is running throughout a series of filters and data point selection logics. Results show that the algorithm is robust with respect to any box mounting position or vehicle, with, on average, a convergence time of less than 20 minutes to the correct angles.