A star identification algorithm was developed for a charge-coupled device （CCD） or complementary metal-oxide-semiconductor （CMOS） autonomous star tracker to acquire 3-axis attitude information for a lost-in-space ...A star identification algorithm was developed for a charge-coupled device （CCD） or complementary metal-oxide-semiconductor （CMOS） autonomous star tracker to acquire 3-axis attitude information for a lost-in-space spacecraft. The algorithm took advantage of an efficient on-board database and an original “4- star matching” pattern recognition strategy to achieve fast and reliable star identification. The on-board database was composed of a brightness independent guide star catalog （mission catalog） and a K-vector star pair catalog. The star pattern recognition method involved direct location of star pair candidates and a sim- ple array matching procedure. Tests of the algorithm with a CMOS active pixel sensor （APS） star tracker result in a 99.9% success rate for star identification for lost-in-space 3-axis attitude acquisition when the angular measurement accuracy of the star tracker is at least 0.01°. The brightness independent algorithm requires relatively higher measurement accuracy of the star apparent positions that can be easily achieved by CCD or CMOS sensors along with subpixel centroiding techniques.展开更多
On the basis of analyzing CCD signals timing and star image processing, a new design and a special parallel architeeture for improving star image processing are presented in this paper. In the design, the operation mo...On the basis of analyzing CCD signals timing and star image processing, a new design and a special parallel architeeture for improving star image processing are presented in this paper. In the design, the operation moving the data in expanded windows, ineluding the star, to the on-ehip memory of DSP is arranged in the invalid period of CCD frame signal. While the CCD saves the star image to memory, DSP processes the data in the onehip memory. This parallelism greatly improves the effieieney of processing. DSP HOLD mode and CPLD teehnology are used to make a shared memory between CCD and DSP. The five lightest stars in the star aequisition stage are aequired in only 3.5 ms. In 43μs, the data in five expanded windows ineluding stars are moved into the internal memory of DSP, and in 1.6 ms, five star eoordinates are aehieved in the star tracking stage.展开更多
基金Supported by the National Key Basic Research and Development (973) Program of China (No. G2000077606 )
文摘A star identification algorithm was developed for a charge-coupled device （CCD） or complementary metal-oxide-semiconductor （CMOS） autonomous star tracker to acquire 3-axis attitude information for a lost-in-space spacecraft. The algorithm took advantage of an efficient on-board database and an original “4- star matching” pattern recognition strategy to achieve fast and reliable star identification. The on-board database was composed of a brightness independent guide star catalog （mission catalog） and a K-vector star pair catalog. The star pattern recognition method involved direct location of star pair candidates and a sim- ple array matching procedure. Tests of the algorithm with a CMOS active pixel sensor （APS） star tracker result in a 99.9% success rate for star identification for lost-in-space 3-axis attitude acquisition when the angular measurement accuracy of the star tracker is at least 0.01°. The brightness independent algorithm requires relatively higher measurement accuracy of the star apparent positions that can be easily achieved by CCD or CMOS sensors along with subpixel centroiding techniques.
文摘On the basis of analyzing CCD signals timing and star image processing, a new design and a special parallel architeeture for improving star image processing are presented in this paper. In the design, the operation moving the data in expanded windows, ineluding the star, to the on-ehip memory of DSP is arranged in the invalid period of CCD frame signal. While the CCD saves the star image to memory, DSP processes the data in the onehip memory. This parallelism greatly improves the effieieney of processing. DSP HOLD mode and CPLD teehnology are used to make a shared memory between CCD and DSP. The five lightest stars in the star aequisition stage are aequired in only 3.5 ms. In 43μs, the data in five expanded windows ineluding stars are moved into the internal memory of DSP, and in 1.6 ms, five star eoordinates are aehieved in the star tracking stage.
