For an accurate measurement of ship's attitude the paper develops an automatic on-line measurement system which uses four servo-type accelerometers and one servo-type inclinometer which are appropriately located on the ship. Through the location of the accelerometers, the heaving, rolling and pitching signals of the ship are separated from each other with adequate linear combinations of the four sensors' outputs. Furthermore, particularly to extract the bias signal of the pitching, one inclinometer is utilized.
By introducing linear dynamic models of the three signals and using Kalman filters, on-line measument of the heaving, rolling and pitching is realized. A bank of Kalman filters are used to overcome a change in some parameters in the dynamics.