›› 2011, Vol. 31 ›› Issue (6): 27-35.doi: 10.3780/j.issn.1000-758X.2011.06.005

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On-board Optimal Nominal Trajectory Guidance Method for Lunar Pinpoint Soft Landing

 LIANG  Dong1,2, LIU  Liang-Dong1, HE  Ying-Zi1,2   

  1. (1 Beijing Institute of Control Engineering,Beijing 100190)
    (2 National Key Laboratory of Science and Technology on Space Intelligent Control,Beijing 100190)
  • Received:2011-03-16 Revised:2011-12-25 Online:2011-12-25 Published:2011-12-25

Abstract: To achieve the pinpoint soft landing (PPL) on a target landing site of lunar surface and minimize the fuel consumption, an optimal nominal trajectory on board rapid programming guidance method for lunar PPL was studied, based on the proposed guidance strategy with on board autonomous landing site selection by LIDAR. Firstly, according to the 3-D spherical nonlinear orbit dynamics model, the optimal control problem of trajectory optimization was transformed into a nonlinear program problem (NLP) by using Legendre-Gauss-Lobatto pseudospectral method. Secondly,sequential quadratic programming (SQP) method was used to solve the transformed problem. Finally,the optimal trajectory was verified by using genetic algorithm. And a method of providing initial value database for SQP on board trajectory programming by using genetic algorithm was proposed. The numerical simulation results show this methodology and strategy for optimal nominal trajectory on board rapid programming can meet the need of lunar PPL real time guidance.

Key words: Guidance, Pinpoint landing, Optimal nominal trajectory, Pseudospectral method, Sequential quadratic programming, Genetic algorithm, Lunar exploration