The relative pose estimation of the space target is indispensable for on-orbit autonomous service missions. Line segment detection is an important step in pose estimation. The traditional line segment detectors show impressive performance under sufficient illumination, while it is easy to fail under complex illumination conditions where the illumination is too bright or too dark. We propose a robust line segment detector for space applications considering the complex illumination in space environments. An improved two-dimensional histogram construction strategy is used to optimize the Otsu method to improve the accuracy of anchor map extraction. To further improve line segment detection’s effect, we introduce an aggregation method that uses the angle difference between segments, the distance between endpoints, and the overlap degree of segments to filter the aggregation candidate segments and connect disjoint line segments that probably came from the same segment. We demonstrate the performance of the proposed line segment detector using a variety of images collected on a semiphysical simulation platform. The results show that our method has better performance than traditional line segment detectors including LSD, Linelet, etc., in terms of line detection precision.

This paper proposes an optimal maneuver strategy to improve the observability of angles-only rendezvous from the perspective of relative navigation. A set of dimensionless relative orbital elements (ROEs) is used to parameterize the relative motion, and the objective function of the observability of angles-only navigation is established. An analytical solution of the optimal maneuver strategy to improve the observability of angles-only navigation is obtained by means of numerical analysis. A set of dedicated semi-physical simulation system is built to test the performances of the proposed optimal maneuver strategy. Finally, the effectiveness of the method proposed in this paper is verified through the comparative analysis of the objective function of the observability of angles-only navigation and the performances of the angles-only navigation filter under different maneuver schemes. Compared with the cases without orbital maneuver, it is concluded that the tangential filtering accuracy with the optimal orbital maneuver at the terminal time is increased by 35% on average, and the radial and normal filtering accuracy is increased by 30% on average.

An optical simulator was designed in loop testing of medium and long range angles-only navigation of spacecraft, which can verify the performance and reliability of the hardware, software and algorithms of the angles-only navigation vision sensor. Firstly, the system description of the optical simulator was given, including the hardware composition and the star map simulation software design. The commercial and off-the-shelf components were selected as the hardware, which could greatly save research and development costs and shorten the development cycle. Then, the relationship between screen brightness and star magnitude, and the optical principle of the optical simulator were emphatically introduced. Finally, the star map simulation of the optical simulator was tested, and an angles-only navigation model based on Clohessy-Wiltshire (CW) equation was introduced for hardware in loop testing, which verified the optical simulator after geometric calibration could be used for hardware in loop testing of medium and long range angles-only navigation of spacecraft. The relative position accuracy is increased by 25.5%, and the relative speed accuracy is increased by 31.3% compared with that before geometric calibration at the terminal time.