Estimation of Ship Heave and Pitch Under Wave Loads Using Kalman Filtering

Ships or any marine vessels experience loads in form of dynamic wave and wind forces. These affect the motion of ships in both transverse and longitudinal direction. The motions of ship are an important parameter to be controlled as well as to be known in order to prevent any failures like capsizing or structural instability. Therefore, it is of utmost importance to predict the ship motions. This paper attempts to study the ship motions using Kalman filter (KF) considering a regular sea state. Initially, the dynamic longitudinal loads are obtained by the long-term prediction method on basis of ship motion calculations using strip theory. The measurements are then corrupted via noise to simulate practical observations. The unknown parameters like sectional wave exciting force and sectional hydro-mechanic force are then estimated using KF by analysing the problem as a 2D problem using linear Airy wave theory under assumption that the body is a rectangular floating frame. The problem can then be extended to actual load conditions and sea states.