title: An accuracy measurement method for star trackers based on direct astronomic observation.
abstract: Star tracker is one of the most promising optical attitude measurement devices and it is widely used in spacecraft for its high accuracy. However, how to realize and verify such an accuracy remains a crucial but unsolved issue until now. The authenticity of the accuracy measurement method of a star tracker will eventually determine the satellite performance. A new and robust accuracy measurement method for a star tracker based on the direct astronomical observation is proposed here. In comparison with the conventional method with simulated stars, this method utilizes real navigation stars as observation targets which makes the measurement results more authoritative and authentic. Transformations between different coordinate systems are conducted on the account of the precision movements of the Earth, and the error curves of directional vectors are obtained along the three axes. Based on error analysis and accuracy definitions, a three-axis accuracy evaluation criterion has been proposed in this paper, which could determine pointing and rolling accuracy of a star tracker directly. Experimental measurements confirm that this method is effective and convenient to implement. Such a measurement environment is close to the in-orbit conditions and it can satisfy the stringent requirement for high-accuracy star trackers.
authors.affiliation: Department of Precision Instrument, Tsinghua University, Beijing, China.|State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, China.
authors.forename: Ting
authors.initials: T
authors.lastname: Sun
authors.affiliation: Department of Precision Instrument, Tsinghua University, Beijing, China.|Electrical Engineering Division, Department of Engineering, University of Cambridge, United Kingdom.|State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Xing
authors.affiliation: Department of Precision Instrument, Tsinghua University, Beijing, China.|Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing, China.
authors.forename: Xiaochu
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Precision Instrument, Tsinghua University, Beijing, China.|State Key Laboratory of Precision Measurement Technology and Instruments, Tsinghua University, Beijing, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: You
authors.affiliation: Electrical Engineering Division, Department of Engineering, University of Cambridge, United Kingdom.
authors.forename: Daping
authors.initials: D
authors.lastname: Chu