Research On The Measurement Of The Skylight Polarization Pattern And Its Assisted Directional Technology

How to improve the autonomy, the accuracy and reliability, and to reduce thecost of the navigation system is an important research topic in today’s integratednavigation. As a novel aided navigation system, polarized-light navigation isincreasingly valued. This novel aided navigation system can be self-directed, thesystem error of it is not accumulating with time. Small volume and mass, less powerconsumption are distinct characters of the navigation devices with a very broadapplication prospect. According to the polarization pattern of the daytime sky andthe characteristic, this thesis designed and built the imaging polarimetrymeasurements system and did some correlative experiments. Finally this thesisstudied the polarized-light navigation algorithm for aided navigation system.This article starts with the theory of the atmospheric scattering and discussesthe causes of the atmospheric scattering in the sky, then Rayleigh scattering and Miescattering theory. The article analyzes the mechanism of production and distributionof the polarization patterns in the sky. The principles of the polarized-light aidednavigation are described, and the equations of the polarized-light measurementmodels of attitude errors are developed.In order to research and analysis the characteristic of the polarization pattern inthe sky, the article is based on a single Rayleigh scattering theory modeling andsimulation of the all-sky polarization model and using2-D projection for a3-Dmodel. Then an imaging polarimetry measurements system is constructed forskylight polarization detection according to the Mueller matrix and Stokes vectormethod. Specifications of the measurement system are obtained after calibration.And then we do a large number of experimental analysis with the measuring system.According to the calculated results the stability and symmetry of the skylightpolarization pattern are analysed, then comparing with the theoretical models.Furthermore, we discuss limited condition and feasibility of the skylightpolarization pattern (degree of polarization and angle of polarization) for the aidednavigation system.To increase the attitude errors observation performance of SINS/GPS integratednavigation system, the polarized-light aided navigation methods are proposed.Finally, simulations on polarized-light/SINS/GPS integrated system performanceindicate that attitude error estimation is improved.