Research On The Application Of Star Sensor Based On Spectral Polarization Technique For Airborne Platform

Star sensor is a kind of high precision satellite attitude measuring instrument,which is extremely important in the field of space.It uses fixed star for azimuth recognition to provide three-axis attitude of inertial space for the aircraft.Because of its extremely sensitive to the sky background light,star sensors are mostly us ing in satellites,strategic missiles,space shuttles.In recent years,researchers have begun to apply star sensor navigation technology to strategic bombers,reconnaissance aircraft,high-altitude balloons,and even ships because of the increasing maturity of the joint control,the photoelectric detection capability and image information processing.Aiming at the application requirements of star sensors in airborne platform,this paper provides theoretical basis and technical method to the application of star sensors in engineering,combined with the study of the characteristics of the target and the background,the characteristics of the atmospheric radiation transmission,the design of the detection system.The main work of this dissertation including the following aspects:(1)The research on spectral characteristics and polarizing properties of the sta r target and sky background.Conducting in-depth study of the spectral characteristics and polarizing properties of star target and sky background,based on spectral imaging and optical polarization theory.Choosing G,M,K stars as guide stars,and calculating star spectral characteristics according to theory of blackbody radiation.Analyzing the sky background spectral characteristics at different atmospheric visibility,altitude,solar zenith angle and viewing zenith angle using PCModWin5 software.Introducing the degree of polarization to describe the contrast ratio between star target and sky background,and proposing the method of promoting the contrast ratio between star target and sky background.(2)The research of atmospheric radiation transmission characteristics.Based on the principal theory of atmospheric radiation transmission,such as atmospheric transmissivity,atmospheric contours,chemical composition in the atmosphere,calculating the atmospheric scattering and absorption optical depth usi ng the HITRAN database and the line by line integral method.Calculating aerosol extinction optical depth using empirical formula estimation based on the meteorological parameter.After that,get the result of atmospheric transmissivity from the outer limit of atmosphere to the different height above ground based on the optical depth,and contrast with the simulation result of PCModWin5,the maximum relative error is less than 9%,the results proved the validity of the atmospheric radiation transmission model.(3)The design of star sensor system and the analysis of detection capability.Based on the analysis results of target,background,atmospheric radiation transmission,via the demonstration of system working band,the design of system structure and the selection of detector,accomplishing the overall concept design of star sensor.Establishing image chain model of the entire system according to the energy transfer and transformational relation of the energy reached the star sensor,which is the rest energy of target and background signal through the transmission path.Building the evaluation index of detecting ability,accomplishing the detection performance evaluation of star sensor based on the simulation result of image plane energy,and coming forward the approach to promote the detecting ability.In brief,the application of star sensors in airborne platform has become an important direction for the development of star sensor technology.This paper carries out relevant exploratory development around the application of star sensors in airborne platform,which will promote the expansion of application domain of star sensor and benefit the posture measurement capability of star sensor.