제어로봇시스템학회:학술대회논문집
- 제어로봇시스템학회 2005년도 ICCAS
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- Pages.894-900
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- 2005
Unscented Filtering in a Unit Quaternion Space for Spacecraft Attitude Estimation
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Cheon, Yee-Jin
(KOMPSAT-3 System Engineering & Integration Dept., Korea Aerospace Research Institute)
- 발행 : 2005.06.02
초록
A new approach to the straightforward implementation of the unscented filter in a unit quaternion space is proposed for spacecraft attitude estimation. Since the unscented filter is formulated in a vector space and the unit quaternions do not belong to a vector space but lie on a nonlinear manifold, the weighted sum of quaternion samples does not produce a unit quaternion estimate. To overcome this difficulty, a method of weighted mean computation for quaternions is derived in rotational space, leading to a quaternion with unit norm. A quaternion multiplication is used for predicted covariance computation and quaternion update, which makes a quaternion in a filter lie in the unit quaternion space. Since the quaternion process noise increases the uncertainty in attitude orientation, modeling it either as the vector part of a quaternion or as a rotation vector is considered. Simulation results illustrate that the proposed approach successfully estimates spacecraft attitude for large initial errors and high tip-off rates, and modeling the quaternion process noise as a rotation vector is more optimal than handling it as the vector part of a quaternion.
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