Autonomous docking using direct optimal control

We propose a method for performing autonomous docking of marine vessels using numerical optimal control. The task is framed as a dynamic positioning problem, with the addition of spatial constraints that ensure collision avoidance. The proposed method is an all-encompassing procedure for performing both docking, maneuvering, dynamic positioning and control allocation. In addition, we show that the method can be implemented as a real-time MPC-based algorithm on simulation results of a supply vessel.Comment: 12th IFAC Conference on Control Applications in Marine Systems, Robotics, and Vehicles (CAMS 2019). IFAC; Daejeon. 2019-09-18 - 2019-09-2

LQG control for dynamic positioning of floating caissons based on the Kalman filter

This paper presents the application of an linear quadratic gaussian (LQG) control strategy for concrete caisson deployment for marine structures. Currently these maneuvers are carried out manually with the risk that this entails. Control systems for these operations with classical regulators have begun to be implemented. They try to reduce risks, but they still need to be optimized due to the complexity of the dynamics involved during the sinking process and the contact with the sea bed. A linear approximation of the dynamic model of the caisson is obtained and an LQG control strategy is implemented based on the Kalman filter (KF). The results of the proposed LQG control strategy are compared to the ones given by a classic controller. It is noted that the proposed system is positioned with greater precision and accuracy, as shown in the different simulations and in the Monte Carlo study. Furthermore, the control efforts are less than with classical regulators. For all the reasons cited above, it is concluded that there is a clear improvement in performance with the control system proposed.The Spanish FEDER/Ministry of Science, Innovation and Universities—State Research Agency is greatly acknowledged for partially funding our research through the SAFE Project (Desarrollo de un Sistema Autónomo para el Fondeo de Estructuras para Obras Marítimas), GrantAgreement: RTC-2017-6603-4. The Regional Ministry of Universities, Equality, Culture and Sports of the Gov-ernment of Cantabria has supported this work through the ControlFond project (Control De Ve-hículos Subacuáticos No Tripulados Para Supervisión De Estructuras Para Obras Marítimas Fondeadas). The authors would like to thank FCC Construcción CO as a collaborator in the de-velopment of the SAFE Project, specially Victor Florez Casillas and Nuria Cotallo Aguado (Tech-nical Direction/Hydraulic and Maritime Works) and Alvaro de Toro Mingo (Machinery Direction). R. Guanche also acknowledges financial support from the Ramon y Cajal Program (RYC-2017-23260) of the Spanish Ministry of Science, Innovation and Universities

Dynamic positioning of ship using backstepping controller with nonlinear disturbance observer

This paper studies the adaptive dynamic positioning control problem of the full-actuated ship with uncertain time-varying environmental disturbances. Considering the disturbances with unknown boundaries, the inversion control technique is combined with the disturbance observation compensation method to design the robust adaptive backstepping control law of the ship dynamic positioning system. The Lyapunov function is adopted to prove the errors of the ship’s position and heading angle are uniformly ultimately bounded using the designed control law. The nonlinear disturbance observer can adaptively estimate and compensate for uncertain external disturbances caused by winds, waves and currents. Afterward, the verification of the proposed controller through a typical CyberShip Ⅱ model subject to environmental disturbances is carried out using a hardware-in-the-loop simulation where a thrust distribution model is established. The simulation results show the effectiveness of the proposed control law

Dynamic positioning of ship using backstepping controller with nonlinear disturbance observer

930-937This paper studies the adaptive dynamic positioning control problem of the full-actuated ship with uncertain timevarying environmental disturbances. Considering the disturbances with unknown boundaries, the inversion control technique is combined with the disturbance observation compensation method to design the robust adaptive backstepping control law of the ship dynamic positioning system. The Lyapunov function is adopted to prove the errors of the ship’s position and heading angle are uniformly ultimately bounded using the designed control law. The nonlinear disturbance observer can adaptively estimate and compensate for uncertain external disturbances caused by winds, waves and currents. Afterward, the verification of the proposed controller through a typical CyberShip Ⅱ model subject to environmental disturbances is carried out using a hardware-in-the-loop simulation where a thrust distribution model is established. The simulation results show the effectiveness of the proposed control law

Review of dynamic positioning control in maritime microgrid systems

For many offshore activities, including offshore oil and gas exploration and offshore wind farm construction, it is essential to keep the position and heading of the vessel stable. The dynamic positioning system is a progressive technology, which is extensively used in shipping and other maritime structures. To maintain the vessels or platforms from displacement, its thrusters are used automatically to control and stabilize the position and heading of vessels in sea state disturbances. The theory of dynamic positioning has been studied and developed in terms of control techniques to achieve greater accuracy and reduce ship movement caused by environmental disturbance for more than 30 years. This paper reviews the control strategies and architecture of the DPS in marine vessels. In addition, it suggests possible control principles and makes a comparison between the advantages and disadvantages of existing literature. Some details for future research on DP control challenges are discussed in this paper

Flexibility and working metod of dynamic positioning

Dinamičko pozicioniranje je sustav pomoću kojeg plovni objekt održava željeni kurs i poziciju isključivo uz uporabu svojih vlastitih potisnika i vijaka. Sam sustav je prilično kompleksan te osim raznih osjetnika obuhvaća i računalni program koji obrađuje dobivene podatke, te potisnike i kormila koji su izvršni organ cijele operacije. Dinamičko pozicioniranje se koristi najviše na odobalnim naftnim platformama, ali i na brodovima koji prate podvodne ronilice, na istraživačkim plovilima, brodovima za kružna putovanja, te brodovima koji polažu kabele. Tehnika rukovanja dinamičkim pozicioniranjem se razlikuje od jednog do drugog plovila i ovisi o njegovim radnim operacijama kao i o obilježjima samog plovila. Cilj ovog rada je predstaviti različite tehnike upravljanja kao i same elemente sustava dinamičkog pozicioniranja. Ovaj sustav se konstantno unaprjeđuje i biva sve učinkovitiji.Dynamic positioning is a system which allows a vessel to maintain the desired heading and position solely by using its own thrusters and propellers. The system itself is quite complex, and besides various sensors it also includes a computer program that processes the data obtained as well as thrusters and rudders which serve as executive organs of the entire operation. Dynamic positioning is most commonly used on offshore oil platforms, but also on ships that track underwater vehicles, research vessels, cruisers, and cable-laying ships. The technique of dynamic positioning differs from one vessel to another, depending on its operations and its very features. The aim of this paper is to present different management techniques as well as the elements of the dynamic positioning system. This system is constantly improving and becoming more efficient

Dynamic positioning with model predictive control

Marine vessels with dynamic positioning (DP) capability are typically equipped with sufficient number of thrusters to make them overactuated and with satellite navigation and other sensors to determine their position, heading, and velocity. An automatic control system is tasked with coordinating the thrusters to move the vessel in any desired direction and to counteract the environmental forces. The design of this control system is usually separated into several levels. First, a DP control algorithm calculates the total force and moment of force that the thruster system should produce. Then, a thrust allocation (TA) algorithm coordinates the thrusters so that the resultant force they produce matches the request from the DP control algorithm. Unless significant heuristic modifications are made, the DP control algorithm has limited information about the thruster effects such as saturations and limited rate of rotation of variable-direction thrusters, as well as systemic effects such as singular thruster configurations. The control output produced with this control architecture is therefore not always optimal, and may result in a position loss that would not have occurred with a more sophisticated control algorithm. Recent advances in computer hardware and algorithms make it possible to consider a model-predictive control (MPC) algorithm that combines positioning control and TA into a single algorithm, which should theoretically yield a near-optimal controller output. This paper explores the advantages and disadvantages of using MPC compared with the traditional algorithm