Structural Design And Analysis Of High Accuracy Star Sensor

CCD star sensor is an avionics instrument used to provide the absolute3-axis attitude ofa spacecraft by utilizing star observations. Since it has been studied for almost half century,many countries abroad have ability to produce CCD star sensor with a3σ accuracy of betterthan1arcsec and it is1σ accuracy of3arcsec domestic. This is one of breakthroughtechnologies in our country astronautics domain. The dividing of accuracy, structural design,finite element analyses and evaluating image quality of the star sensor are comprehensivelydiscussed in this paper from studying the goal to a3σ accuracy of1arcsec.Firstly, the development history and trends, the system composition and measureprinciple of star sensor are introduced. Present research situation abroad is studied and themethod used to get accuracy is confirmed.Secondly, the primary technology factors of star sensor are introduced and the errordividing of some high accuracy star sensors oversea are studied. The factors of influenceprecision and measure to restrain them are analyzed. Error dividing of star sensor is given in amanner of fig with the maximum of every error factor.Thirdly, according to the analyzing of error dividing and design of some high accuracystar sensors oversea, several measures to confirm1σ accuracy of3arcsec are presented. Thestar sensor is separated into three parts in order to minimize thermal coupling effects. AlSiC,which has unfixed coefficient of thermal expansion(CTE) and smaller density is used as thematerial of lens barrel. The processing directional optics is applied. At last, the design of starsensor is worked out.Finally, finite element analysis, including static analysis, dynamic analysis and thermalstress analysis, is applied in structural design. Dynamic analysis contains modal analysis,transient analysis and random vibration. Thermal stress of star sensor at known temperaturecondition is analyzed. Two methods of evaluating image quality are studied and one of themis applied after static analysis and thermal stress analysis. According to the analysis above,structural of star sensor which designed in this paper satisfied the request.