| Polarized light navigation is a kind of natural navigation technology which uses the polarization characteristics of sunlight scattering in the atmosphere.By extracting navigation azimuth information from the distribution characteristics of atmospheric polarization pattern,3D attitude information of carriers including heading,pitch and roll can be calculated.Recent years have witnessed the rapid deveopment of unmanned aerial vehicles thus it puts forward higher requirements on navigation performance such as low cost,low power consumption,high precision,strong anti-interference ability and high autonomy;However,traditional navigation techniques can not meet the above requirements.Therefore,by studying biological navigation techniques,research on polarized light navigation becomes more and more important and has great research significance and military application value in fast north-seeking of rockets and missiles,providing initial attitude information for inertial navigation system,rapid launching missile and autonomous navigation.Based on the above requirements,whole skylight polarization distribution pattern has been built according to the phenomenon of atmospheric polarization and its basic theory,the representation method of polarized light based on Stokes vector has been derived,and a four channel atmospheric polarization information detection system has been designed and built.The polarization degree direction of observed area have been extracted and the distribution characteristics of atmospheric polarization pattern has been verified through polarization information acquisition experiment.On this basis,a heading calculation method based on the position of the sun has been derived.Firstly,the position of sun based on body coordinate frame and geographic coordinate system have been calculated through atmospheric polarization pattern,then heading angle of carrier has been acquired with the help of attitude transformation matrix equations.Meanwhile,the fixed spatio-temporal model of sun and zenith has been established to calculate zenith coordinate through the information of sun position,and method for obtaining pitch and roll information has been derived by setting zenith as spatial feature.In addition to that,the acquisition of 3D-pose information has been achieved,and the accuracy of the algorithm has been verified by three group of experiments.In addition,a BD/MEMS-IMU tightly-coupled integrated navigation system based on DSP6747 and FPGA dual core hardware platform has been designed.To solving the problem of the low precision MEMS-IMU a new fast north seeking method by polarized light navigation for the integrated navigation system has been studied.Finally,vehicle experiments have been conducted and results show that the accuracy and reliability of initial alignment based on polarized light,and the designed BD/MEMS-IMU integrated navigation system has higher precision,better stability and stronger robustness. |
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