Optimal-REQUEST algorithm for attitude determination

D. Choukroun, I. Y. Bar-Itzhack, Y. Oshman

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


REQUEST is a recursive algorithm for least-squares estimation of the attitude quaternion of a rigid body using vector measurements. It uses a constant, empirically chosen gain and is, therefore, suboptimal when filtering propagation noises. The algorithm presented here is an optimized REQUEST procedure, which optimally filters measurement as well as propagation noises. The special case of zero-mean white noises is considered. The solution approach is based on state-space modeling of the K-matrix system and uses Kalman-filtering techniques to estimate the optimal K matrix. Then, the attitude quaternion is extracted from the estimated K matrix. A simulation study is used to demonstrate the performance of the algorithm.

Original languageEnglish
Pages (from-to)418-425
Number of pages8
JournalJournal of Guidance, Control, and Dynamics
Issue number3
StatePublished - 1 Jan 2004
Externally publishedYes

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Aerospace Engineering
  • Space and Planetary Science
  • Electrical and Electronic Engineering
  • Applied Mathematics


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