IMU alignment for smartphone-based automotive navigation

Recent years have seen an increasing interest in making use of the smartphone as a cheap and viable navigation device for land-vehicles. However, smartphone-based automotive navigation suffers from the fact that the orientation of the smartphone´s inertial measurement unit, with respect to the vehicle, in general is unknown. In this study, we present a method for simultaneous vehicle navigation and smartphone-to-vehicle alignment. In addition to the state estimates obtained from applying a standard global navigation satellite system-aided inertial navigation system to estimate the smartphone dynamics, this will also provide us with estimates of the vehicle´s attitude. These estimates are used to improve the navigation solution, and also enables the estimation of additional vehicle, road, and driver characteristics, which requires knowledge of the vehicle´s attitude. The performance of the proposed method is evaluated with both simulations and experimental data.