Robust Azimuth Measurement Method Based on Polarimetric Imaging for Bionic Polarization Navigation

Azimuth information obtained from a polarization pattern in the sky provides many organisms like insects and birds, with the ability to navigate. The aim of this article is to investigate the azimuth method to measure the solar meridian from the pattern of the Angle of E (AOE) vector when it is partially obscured and disturbed. The model of the sky polarization pattern projected onto an imaging sensor is analyzed. The projection characteristic of the solar meridian is proved to be a straight line passing through the principal point, which is composed of pixels with the E-vector orientation 90° in the AOE map. Based on the mutation feature of the gradient amplitude of E-vector orientation 90° and occlusion without mutation on the solar meridian, a robust gradient amplitude and binary integration (GABI) azimuth method for a polarization imaging sensor is proposed. Then, the feasibility and robustness of this method are verified via numerical simulation and outdoor experiments, and the results show that when branches and buildings shield more than 80% of the AOE map, the azimuth measurement method remains effective. The accuracy of azimuth is 0.417° (σ). This indicates that the azimuth can be effectively measured, even in the presence of occlusion and interference.