Automatic on-line measurement of dynamic ship´s attitude

For an accurate automatic online measurement of ship´s attitude we develop an intelligent sensing system which uses one servo-type accelerometer and two servo-type inclinometers, which are appropriately located on the ship. By considering the dynamics of the servo-controlled rigid pendulums of the inclinometers, linear observation equations are derived on the rolling and pitching signals of the ship. Moreover, one accelerometer is utilized to extract the heaving signal. Through the introduction of linear dynamic models and the linear observation equations on the three signals, their online measurement is reduced to the state estimation of the linear dynamic systems. A bank of Kalman filters are used to execute the online state estimation and to overcome changes in parameters in the dynamic models with time lapse