One of the requirements for ships equipped with dynamic positioning system is the ability to maintain a given position in various hydrometeorological conditions. At the same time, efforts at reducing electricity consumption are made in order to reduce operating costs and emissions of exhaust gases, such as sulfur oxides and greenhouse gases such as carbon dioxide (CO2). For this purpose, the ship designer at the design stage must predict both how much energy the ship will theoretically use during operation and how the expenditure can be reduced. The publication presents a comparison of energy consumption with two different approaches to ship positioning: the use of classic dynamic positioning utilizing a set of thrusters and by using a set of anchors. In order to determine the energy consumption during positioning, the matrix method was used, on the basis of which the analysis of the ability to hold the position of the ship (capability plot) was performed, in accordance with the recommendations of the classification society DNV GL. Thanks to this analysis, it was possible to find such a distribution of thrust vectors on propulsors that the ship would not lose its set position under the hydrometeorological conditions specified in the analysis. As a result of comparing the two positioning systems, it turned out that using anchor-based positioning uses 24% less energy than positioning based on a set of thrusters, which translates into 24% less CO2 emissions into the atmosphere.

https://www.mdpi.com/1996-1073/14/3/524/pdf

A Comparative Analysis of Energy Consumption by Conventional and Anchor Based Dynamic Positioning of Ship

A robust H∞ sampled-data stabilization problem for nonlinear dynamic positioning (DP) ships with Takagi-Sugeno (T-S) fuzzy models is discussed in this paper. Input delay approach is used to convert the sampleddata DP ship system to a fuzzy system with time-varying delay. Adequate conditions are derived to determine the system’s asymptotical stability and achieve H∞ performance via Lyapunov stability theorems. Then, the fuzzy sampled-data controller is obtained by analyzing the stabilization condition. Simulation result shows that the proposed method and the designed controller for a DP ship are effective so that the DP ship can maintain the desired position, heading and velocities in the existence of varying environment disturbances.

Robust Fuzzy Sampled-Data Control for Dynamic Positioning Ships

Dynamic positioning of floating caissons based on the UKF filter under external perturbances induced by waves

The article describes the process of construction and testing a floating offshore drilling platform model with focus on cooperation of its diverse subsystems in order to stabilise the position and control the movement of the platform In real-life applications, advanced off-shore oil-rigs are indeed floating without any scaffolding or concrete basis, so the waves and shore current continuously disrupt their position Since the place of drilling is fixed, those movements are able to damage or even break the drill, which leads to serious environment contamination by the emerging oil This paper considers PID controller as a dynamic positioning system with a reference system based on image recognition

Floating Oil Platform Model with Dynamic Positioning and Reference System

Design a class of ship location fuzzy PID controller to solve the difficult problem of dynamic positioning control, due to external environmental factors (wind, wave, current. ect) random noise on the movement of ships at sea. Realize dynamic positioning control on inaccurate mathematical model, large inertia, and nonlinear target ship by amending parameter on line, based on ship-based system errors using nonlinear filtering method to filter noising of the position signal. Simulate and analyze on a ship system. The results show that the system response speed goes faster and overshoot is small. Nonlinear filter achieves a better ability to filter out noise interference. The overall effect of the ship system control is good.

Zhi-qing Liu

Papers

Design of fuzzy PID controller for ship dynamic positioning