Drone Navigation Based on Integrated MEMS Inertial and Polarimetric Camera Measurements

This paper describes an innovative method to measure the heading angle of a platform by exploiting the polarization state of Sunlight. Measuring the polarization state of Sunlight in a certain celestial region, the Rayleigh Single Scattering model can be used to identify the Sun meridian/anti-meridian in a polarized image to support navigation systems. A polarimetric camera is used to acquire several images containing the Sun meridian/anti-meridian. Once the Sun azimuth and attitude data are acquired at the current time and location, the position of the Sun meridian/anti-meridian in the local reference frame can be compared with its position expressed in the camera reference frame by exploiting inertial sensors. In this way, an accurate heading angle measure can be performed to improve the navigation performance of autonomous vehicles. Several tests have been carried out: (i) ground tests were performed to evaluate the proposed method by using a polarimetric camera and a certified inertial unit on a tripod; (ii) flight tests were performed to assess the achieved performance installing the polarimetric camera on-board a drone. As shown by the obtained results, the proposed method ensures accurate heading angle estimates by exploiting the polarization vector information that can be used in an autonomous integrated navigation system when satellite navigation is not available in nominal conditions.