Localization of a Space Rover and Estimation of Rotational Parameters WITHOUT Calculating Derivatives

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


Optimization, Radio Wave Based Positioning, Rovers for Small Planetary Bodies


In previous work, we proposed a method of localization for a rover, which uses measurement of round-trip propagation delay of radio waves between a rover and a mother spacecraft [1]. It is useful for a rover on any size of plan etary body, while conventional methods could not apply to a rover on a small planetary body with a diamter less than 1000 (m). However, the method assumed that precise information about the rotation of the small planetary body is known. This paper describes a method to estimate rotational parameters together with the position of the rover based on radio-wave-based measurements. The method is formulated as an optimization problem by deļ¬ning performance index based on estimation error in measurement. This optimization problem is dynamic and non linear, moreover, the variables have different scales. A solution of this optimization problem is described here by applying a method without calculating derivatives [2]. Simulation results are also shown to evaluate the estimation accuracy of the proposed method.

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