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iSAM: Incremental Smoothing and Mapping

Author: Kaess

Year: 2008

Notes:

  • smoothing information matrix is naturally sparse, but in filtering approaches it becomes dense because of marginalization
  • periodic variable reordering for loops (?)
  • fast algorithm for data association
  • solution based on QR factorization
  • iterative optimization avoids the problem arising from wrong linearization point
  • QR factorization with givens rotation -> set to zeros all entries below diagonal, constructs the Q matrix
  • number of givens rotation is independant of the length of the trajectory
  • With loops, information matrix remains sparse but R becomes dense -> variable reordering with COLAMD
  • Uses ML data association (better than NN as it takes uncertainties into account, but slower)
  • The full covariance matrix is never calculated, marginals are obtained performing backsubstitution on R matrix

Commentaires:

  • Equations trés claires