Localization of a Space Rover on a Small Planetary Body with Uncertain Rotation

S. Kanata, H. Nakanishi, and T. Sawaragi (Japan)


Localization, Optimization, Gradient Method, Uncertainty in Rotational Parameters


We proposed a method of localization for a space rover, which uses measurement of round-trip propagation delay between a rover and a mother spacecraft based on radio waves[1]. The localization accuracy of the method de pended on accuracy of the rotation of the planetary body. In this paper, a method to estimate rotational parameters together with position of the rover using radio-wave-based measurements is proposed. Estimation method of rota tional parameters are formulated as an optimization prob lem. Gradient method has been applied to solve the opti mization problem in this paper. However, normal solution based on gradient is useless because value of performance index is too sensitive to some of components of state vec tor to solve the optimization problem. In order to avoid this problem, searching process based on gradient vector has been divided into three steps. Simulation results assumed small planetary body are shown to evaluate estimation ac curacy of the proposed method.

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