Robust control allocation design for marine vessel

Abstract

This study proposes a new approach to control design problems for marine vessels moored or controlled by several actuators. For special purposes, vessels are sometimes positioned by the actuators installed on them or by the assistance of additional systems. It is well known that there are many types of actuators in real applications. Among them, the useful and widely applicable actuator systems are the thruster and the mooring winch. Related to the use of these systems in actual plants, the control allocation problem is an important issue. In order to address this issue, many results have been given and verified by many researchers with a two steps process, in which the controller design and the control allocation process are independently carried out. This is a desirable approach since the stability and performance of the control system are ignored, and hence, the realizations of the basic objectives of the control system design are not guaranteed at all.A new design method is proposed in this paper, and in this method, the controller design and control allocation problem are integrated through a one-step process in which the treatment of system stability, control performance, and allocation problem is unified by a condition obtained from H∞control basis.