Automatic on‐line measurement of ship's attitude by use of servo‐type inclinometers

Abstract

AbstractAn accurate measurement of dynamic ship's attitude is important for not only correcting data obtained with sonars in searching seabed patterns but also controlling the attitude of a high‐quality ship. From this viewpoint, a previously developed automatic measurement system measured the heaving, rolling, and pitching of a ship by processing outputs of four servotype accelerome‐ters appropriately located on the ship. However, this measurement system required excessive computational time for data processing because it adopted both the maximum entropy method and an optimization procedure to seek the unknown heaving, rolling, and pitching parameters. To realize the on‐line measurement of the three signals, this paper proposes a new automatic measurement system using two servotype inclinometers and one accelerometer. This measurement system introduces linear dynamic models and linear observation equations on the three signals and reduces the on‐line measurement of the three signals to the state estimation of the linear dynamic systems. A bank of Kalman filters is used to execute the on‐line state estimation and to overcome changes in parameters in the dynamic models with time. Since the proposed measurement system utilizes the two servotype inclinometers and one servotype accelerometer, the measurement system will cost less than the previously proposed one.