Integration of a Sun light Polarization Camera and Latest-Generation Inertial Sensors to Support High Integrity Navigation

This paper describes an innovative method to measure the heading angle of a platform by exploiting the Sun light polarization state. The single-scattering Rayleigh model is applied to identify the Sun meridian/anti-meridian in a polarized image after the knowledge of the Sun light polarization state in the considered sky region. A polarimetric camera is adopted to acquire several images that include the Sun meridian/anti-meridian. Based on the knowledge of the Sun azimuth and elevation at given place and time, it is possible to compare the position of the Sun meridian/anti-meridian in the local reference frame with its position in the camera reference frame. From this comparison, the heading angle can be accurately estimated and used to correct the typical drift errors of a MEMS-based, low-cost inertial measurement unit. The initial heading angle is estimated with a Kalman filter. Then, in order to observe the performance reached a comparison between the compensated and uncompensated system is evaluated. The adoption of a compact and lightweight polarimetric camera can improve the navigation performance of autonomous systems, such as Drones and Remotely Operated Vehicles.