Dynamic positioning system for a ship on harbour manoeuvringwith different observers. Experimental results

In cases when the navigational space of the manoeuvre performed by the ship is severely limited, the procedures making use of the rudder blade, propeller screw, and thrusters are very complicated. Such situations take place when the ship manoeuvres inside the harbour area and in those cases the structure of the control system is very complex. The article describes the algorithm of multivariable control of ship motion over the water surface, which makes use of the state vector consisting of 6 variables. Three of them, which are the position coordinates (x, y) measured by the DGPS system and the ship heading y measured by gyro-compass, were obtained experimentally. The three remaining variables, which are the velocities in surge u, sway v, and yaw r directions, were estimated by Kalman filter, Kalman- Bucy filter and extended Kalman filter, respectively. The control algorithms making use of these observers were examined using the training ship „Blue Lady” which was navigated on the lake Silm in Ilawa/Kamionka in the Ship Handling Research and Training Centre owned by the Foundation for Safety of Navigation and Environment Protection. The experimental results obtained using control systems with three observers were finally compared between each other.