Applications of Adaptive Control to Ship Steering

Abstract

Abstract This paper describes the application of various adaptive control techniques to the automatic steering of ships. At the Control Laboratory an adaptive autopilot has been developed which is now commercially available. The design is mainly based on the model-reference approach. The adaptive properties of this autopilot have reduced the number of manual settings, leaving only a few settings which can be easily understood by the operator. The autopilot is able to change heading in a predictable way and to keep a ship on her course, either with maximum accuracy or with minimum fuel consumption. Similar principles have been applied to the design of a new type of autopilot, which not only controls the heading of the ship but also the roll. For both control loops only one single actuator is used: the rudder. In order to realize such a system additional adaptive features have to be added to those already present in the course controller. Finally the application of adaptive control to the hydraulic rudder servo system is described. These control systems are mostly based on a relay as actuator. The switching of the relay is governed by a table which contains the time intervals necessary for a certain rudder displacement. An adaptive scheme has been implemented to update the table in case its values appear to be wrong.