Hybrid DP Simulations

Large offshore windfarm development has driven the need for next-generation simulators. These tools are of great utility in both analysis and design. Firstly, they offer the ability to combine advanced dynamic positioning and gangway simulation to evaluate operational safety limits across a large spectrum of weather conditions. Secondly, they can be used as a design tool, in which many variants of design parameters can be altered and simulated, evaluating the design choices with highest efficacy. This paper presents SINTEF Ocean’s vessel simulator, VeSim, and its results in a numerical DP3 study of a windfarm support vessel operating in DP mode near a platform. These results are presented with a thorough validation against model-scale test results, also performed by SINTEF Ocean in its Ocean Basin Laboratory. In these tests, VeSim used SINTEF Ocean’s in-house DP algorithm to control the model-scale vessel in a realtime hybrid testing environment, which is extensible to arbitrary controller designs. Through this validation task, the simulator’s value is demonstrated as an effective tool for dynamic positioning simulation in its own right. Additionally, the approach taken is shown to emphasise VeSim’s use in both a hardware-in-the-loop and software-in-the-loop testing environment. The simulation framework is described, including its modelling of environments, propulsion and hydrodynamics, and its implementation of SINTEF Ocean’s in-house DP algorithm. The model test are described in detail, with especial focus on the use of VeSim and how its DP-controller was used as a controller in a hybrid testing environment. The tools and approaches described in the paper offer designers a variety of approaches, both computational and computational-experimental, aiding them in making the best design choices for future offshore vessels.