Article

Journal of Mechanical Science and Technology

, Volume 23, Issue 1, pp 195-203

Transfer alignment considering measurement time delay and ship body flexure

  • Lyou JoonAffiliated withDepartment of Electronics Engineering, Chungnam National University Email author 
  • , Lim You-CholAffiliated withElectronics Department, Korea Aerospace Research Institute

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Abstract

This paper deals with the transfer alignment problem of strap-down inertial navigation systems (SDINS), using electro-magnetic (EM) log velocity information and gyrocompass attitude information of the ship. Major error sources for velocity and attitude matching are lever-arm effect, measurement time-delay, and ship-body flexure (flexibility). To reduce these alignment errors, an error compensation method based on delay state augmentation and DCM (direction cosine matrix) partial matching is devised. A linearized error model for a velocity and attitude matching transfer alignment system is devised by first linearizing the nonlinear measurement equation with respect to its time delay, and augmenting the delay state into conventional linear state equations. DCM partial matching is then properly combined with velocity matching to reduce the effects of a ship’s Y-axis flexure. The simulation results show that this method decreases azimuth alignment errors considerably.

Keywords

Kalman filter Measurement time-delay Ship body flexure SDINS Transfer alignment