A new approach for ship motion control based on experiment

In this paper, the authors propose a new approach to control problem of the marine vessels which are moored or controlled by actuators. The vessel control system is basically based on the Dynamic Positioning System(DPS) technology. And, using DPS and sensing system, the actuators are installed in the vessel to be positioned in the specified area. There are many types of actuator system in the real applications. The useful and widely applicable systems are thruster and mooring winch based systems. It may be difficult to compare the control performances of two types. If we consider this problem in point of usefulness including cost, we can easily find out that the mooring winch system is more useful and popular to the real field than the thrust system except the special purpose. Considering these facts, in this paper we consider a DPS design problem which can be extended to the many application fields including two types of actuator system. The main object of this paper is to obtain more useful control design method for DPS. In this problem, a complicate fact is the control allocation. For this problem, many results have been given and verified by other researchers with a process followed from two individual steps. It means that the controller and control allocation design process is carried out individually. In this paper, the authors give more sophisticated design solution for this issue. The authors propose a new design method in which the controller design and control allocation problem is considered simultaneously. In other word, the system stability, control performance and allocation problem are unified by a LMI(linear matrix inequality) based on control theory. Because, as well known, LMI expression gives us a solution so efficiently. The usefulness of proposed approach is verified by experiment with a supply vessel model and found work well.