A highly robust bionic polarization orientation method for night applications

Autonomous navigation is a key technology for unmanned motion platforms to perform their tasks smoothly. The current approaches for daytime polarization navigation have been extensively researched. However, the polarization light intensity is the fundamental information within the polarization image, and the light intensity at night is 6–8 orders of magnitude lower than that during the day, which increase the noise and the loss of local polarization information due to occlusion, resulting in a significant decrease in the polarization orientation accuracy. Aimed at the problem, a bio-inspired model is introduced to denoise and enhance weak nighttime polarization patterns. Further, to address the issue of outlier interference in the occluded environment during practical application, a fast-fitting method of the solar meridian based on the anti-symmetric distribution of the polarization angle adjusted by Proportional and Differential (PD) control is proposed. The experimental results show that the method proposed in this paper achieves a dynamic orientation error Root Mean Square Error (RMSE) of 0.7° in the weak polarization mode at night and in the presence of local occlusion. The proposed method has strong robustness under weak polarization occlusion at night, and the orientation accuracy is improved by 97% and 80% in comparison to the least squares method, which provides a new method for polarization navigation at night. This effectively improves the robustness and environmental applicability of the bionic polarization compass for nighttime applications.