Design Of Polarized Light Real-time Positioning System

Compared with traditional positioning methods,there are many advantages for using polarized light in the sky to realize positioning,such as no dependency on artificial signals,error-free accumulation,strong anti-interference ability and so on.Aiming at the existing problems in the positioning process,the polarized light real-time positioning system is constructed based on the principle of positioning using polarized light and geomagnetic field proposed by our subject group,to achieve the following functions: firstly,it can achieve the synchronization of polarization azimuth data acquisition within the single-chip microcomputer,and reduce the complexity of the system data bus and that of PC receiving data.Then,it can also solve the problems of double solutions of solar altitude angle and azimuth,realize real-time measurement of positioning system,and improve the environmental adaptability of positioning system.Finally,the attitude conversion matrix is calculated,which can reduce the steps of adjusting the pitch and roll,and decrease the effects of pitch and roll on positioning result.In the meantime,it can improve the real-time performance and environmental adaptability of positioning system.The polarized light real-time positioning system is constructed based on the principle of positioning using polarized light and geomagnetic field,which mainly includes hardware and software systems.The hardware systems mainly include four polarization azimuth acquisition modules,the sun vector judgment module,STM32 data synchronization and integration module as well as three-dimensional electronic compass;the software systems mainly include STM32 program and LabVIEW program.Four polarization azimuth acquisition modules are used to get the polarization azimuths of the four directions in the sky.The sun vector judgment module is designed to solve the problems of double solutions of solar altitude angle and azimuth,which result from the polarization vector.STM32 data synchronization and integration module is used to reduce the complexity of the system data bus and that of PC receiving data.In the meantime,it can achieve the synchronization of polarization azimuth data acquisition.In order to reduce the steps of adjusting the pitch and roll,the attitude conversion matrix is calculated according to the pitch and roll which are provided by three-dimensional electronic compass.The software solutions are used to control the data acquisition and calculation.The tests of polarized real-time positioning system were carried out,including tests of four polarization azimuth acquisition modules,test of sun direction vector judgment module,test of attitude conversion matrix,test of short time continuity and test of daytime discontinuity.The test results show that: firstly,four polarization azimuth acquisition modules’ errors are all below ±0.2° indoors.Secondly,the sun vector judgment module can judge the sun direction vector in real time,and improve environmental adaptability of positioning system.Thirdly,when the pitch and roll are-6.4° and-5.1°,the errors of longitude and latitude are-0.6°~+0.8° and-0.9°~+1.0° respectively.Compared with the method without using conversion matrix,the errors are-0.3°~+1.5° and-5.2°~-1.4°.Hence,the attitude conversion matrix can reduce the effect of pitch and roll on positioning result.In the meantime,it can improve the real-time performance and environmental adaptability of positioning system.Finally,the maximum errors of longitude and latitude are ±1° and ±1.5° respectively in a continuous test of about 55 minutes,and the polarized light real-time positioning system can be used for daytime positioning.Due to the advantages of high positioning accuracy,real-time performance,environmental adaptability and good stability,the polarized light real-time positioning system can be applied to the actual positioning.