Underway Replenishment Control For Vessels Cruising In Formation

Over the past few years, along with the increasing development of ships transportation and the demand of automatization of ships, underway replenishment has received increasing attention in the control community. Underway replenishment operations to exchange fuel, food, parts or personnel are common in marine operations, it improves ship's cruisingability and scope of work. It is very important to study on underway replenishment of ship in practice. There are three types underway replenishment strategies:one-to-one, one-to-multiple and multiple-to-multiple. The first type of replenishment problem is relatively simple and thus has well addressed. This paper is aimed at solving one-to-multiple underway replenishment problem wherein there is a team of vessels navigating in formations. In this paper, the problems of ship underway replenishment are systematically studied. The contents are as follows:Firstly, we describe the problem of underway replenishment control for vessels cruising in formations. The problem is dealt with as a synchronizing control problem of the replenishment ship in tracking the team of ships in formation. There are two control objects for supply ship, path tracking control and synchronization control.Secondly, with the first control objects, a nonlinear adaptive PD control method is presented for path tracking control of the replenishment ship, which can despite the presence of environmental disturbances induced by wave, wind and ocean-current. Numerical simulations are provided to validate the correctness and effectiveness of the proposed controller.Thirdly, with the second control objects, we taking into account the case that the information exchange among vehicles may be unreliable, so parameters of the distributed controller are derived based on a consensus algorithm and graph theory, with which the replenishment ship can be synchronized with each of the ships voyaging in formations. We also study the consensus problem with time delay. Numerical simulations are provided to validate the correctness and effectiveness of the proposed controller.Fourthly, simulations by Matlab/simulink proved that control targets of underway replenishment are achieved with the proposed path following controller and synchronization controller. Finally, the main conclusions of this paper are summarized and the work for future research is put forward.