An Optical Autonomous Navigation Method for Lunar Satellite and Hardware-in-the-Loop Ground Test
- Paper number
IAC-08.C1.4.6
- Author
Prof. Guo Li, China
- Coauthor
Mr. Chunling Wei, China
- Year
2008
- Abstract
An optical autonomous navigation system for lunar satellite based on imaging ultraviolet sensor and star sensor is studied in this paper. The geometry and filtering orbit determination methods are given. The line of sight (LOS) and range from the center of the moon can be derived from the coordinates of its image center and apparent radius of the image in CCD frame. Then the measured LOS and distance are fed into navigation filter together with inertial attitude which obtained from star sensor and gyros. The simulation result shows that the uncertainty of LOS of moon center dominates the navigation error. Without range measurement, the navigation filter can also converge to acceptable accuracy, but the convergent time is much longer than the scenario with range measurement. Then the Cramer-Rao lower bound (CRLB) is adopted to evaluate the performance of the proposed navigation method. The CRLB obtained according to the system and observation model defines the best achievable performance of the corresponding navigation system. The navigation performance is dominated by the systematic errors in the system, such as misalignment between imaging lunar sensor and star sensors, and LOS measurement bias. A self-calibration method is proposed to eliminate the negative effects of systematic errors, which utilizes the orbital mechanics constraint and yaw maneuver to estimate the measurement bias. A state expanded navigation filter to deal with measurement bias is designed and the simulation result validates the superiority of the method. The simulation result shows that the concept of optical autonomous navigation for lunar satellite is feasible, although a lot of engineering difficulties should be careful considered. A hardware-in-the-loop ground test system is constructed for preparatory experiment on the proposed autonomous navigation system, and it mainly consists of orbit and attitude generator, imaging lunar sensor, star sensor, lunar imaging simulator, kinetic star simulator and navigation computer. The proposed navigation algorithm and computer architecture are checked and verified through the ground experiment. In comparison with autonomous navigation methods in the literature, this paper stresses on-board calibration of systematic errors and hardware-in-the-loop test of optical autonomous navigation system.
- Abstract document
- Manuscript document
(absent)