Research On Methods Of Spacecraft Attitude Determination Based On Star Sensor

Spacecraft attitude determination technology plays an important role in spacecraftattitude control and space remote sensing positioning. The attitude determinationtechnology based on the star-sensor shows great advantages on attitude control. It isreliable, fast and precise. This paper mainly researches on the static altitudedetermination algorithm by using single or two star-sensors, and the attitude filteringmethods by using star-sensors and gyros. The main work of this paper is concluded asfollows.Firstly, the effective detection and identification of stars from the star image is ofgreat important. A scheme of producing simulated star image is proposed in the paper.Then the issue of star image processing and noise removing is discussed. Because of thedisadvantage of detection algorithm with connected-components and static box, thedetection algorithm with dynamic-box is proposed. Simulations indicate that theproposed algorithm is more accurate and effective when the true star quantity andstar-spot size is unknown. The accuracy of spot-centroid extraction algorithm isanalyzed by theoretical analysis and simulation, and the results could be helpful to thechoice of parameter of PSF of the star-sensor.The performances of the three static algorithms, Euler-q, MLS, and QUEST areanalyzed in different optical field of star-sensor. Because of the poor accuracy aroundthe optical axis of star-sensor, the method using star-sensor with larger optical field oremploying two star-sensors with optical axis perpendicular to each other is proposed.Simulations show that the proposed method can effectively improve the attitudeprecision.For the requirement of high precision attitude tracking, the satellite attitudesystems combining star-sensors and gyros are applied widely. Using quaternion statevector, the state-space model and filter algorithm on the attitude tracking problem ispresented. Simulations reveal the performances of the algorithm in different stability ofthe platform, error of the star-sensors and drift noise of the gyros. Meaningfulsuggestions on engineering practice are put forward based on the simulations.This paper studies on some key problems in the attitude determination based onstar-sensors. Several improvements are made, and validated by simulations. The authorhope that the effort of this paper could be helpful in the engineering application ofattitude determination based star-sensors.