Abstract: To deal with the non-linear and non-unique question of six freedom states estimation using the pixels of navigation landmarks, the autonomous position and attitude determination for interplanetary landers is discussed. Based on the invariability of angles in orthogonal transformation, the position and attitude are decoupled for determination by importing the observation angles between of measured lines of sight so as to reduce algorithmic complexity and improve solution precision. For the optimal observation questions, an observation matrix is utilized to analyze the effect of landmark geometry configuration on determination precision, and a novel landmark selecting scheme is proposed to improve the precision of state estimation. Finally, the autonomous optical navigation algorithm is validated and the factors influencing navigation precision is analyzed using Monte Carlo simulations.

Key words: autonomous position and attitude determination, interplanetary lander, navigation landmark, observation angle, optimal observation, geometry optimization