title: Simultaneous localization and calibration for electromagnetic tracking systems.
abstract: BACKGROUND
  In clinical environments, field distortion can cause significant electromagnetic tracking errors. Therefore, dynamic calibration of electromagnetic tracking systems is essential to compensate for measurement errors.
  
  
  METHODS
  It is proposed to integrate the motion model of the tracked instrument with redundant EM sensor observations and to apply a simultaneous localization and mapping algorithm in order to accurately estimate the pose of the instrument and create a map of the field distortion in real-time. Experiments were conducted in the presence of ferromagnetic and electrically-conductive field distorting objects and results compared with those of a conventional sensor fusion approach.
  
  
  RESULTS
  The proposed method reduced the tracking error from 3.94±1.61 mm to 1.82±0.62 mm in the presence of steel, and from 0.31±0.22 mm to 0.11±0.14 mm in the presence of aluminum.
  
  
  CONCLUSIONS
  With reduced tracking error and independence from external tracking devices or pre-operative calibrations, the approach is promising for reliable EM navigation in various clinical procedures. Copyright © 2015 John Wiley & Sons, Ltd.
authors.affiliation: Laboratory for Percutaneous Surgery, School of Computing, Queen's University, Canada.|BioRobotics Research Laboratory, Department of Electrical and Computer Engineering, Queen's University, Canada.
authors.forename: Hossein
authors.initials: H
authors.lastname: Sadjadi
authors.affiliation: BioRobotics Research Laboratory, Department of Electrical and Computer Engineering, Queen's University, Canada.
authors.forename: Keyvan
authors.initials: K
authors.lastname: Hashtrudi-Zaad
authors.affiliation: Laboratory for Percutaneous Surgery, School of Computing, Queen's University, Canada.
authors.forename: Gabor
authors.initials: G
authors.lastname: Fichtinger
mesh_terms: D000465:Algorithms; D000535:Aluminum / Q000737:chemistry; D002138:Calibration; D004574:Electromagnetic Fields; D055590:Electromagnetic Phenomena; D006801:Humans; D009038:Motion; D016011:Normal Distribution; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D013232:Steel / Q000737:chemistry; D025321:Surgery, Computer-Assisted / Q000379:methods*
chemical_list: D013232:Steel; D000535:Aluminum
keywords: calibration; electromagnetic tracking; field distortion compensation; sensor fusion; simultaneous localization and mapping; surgical navigation