Real-time numerical modeling of subsea cable dynamics – Visualized in Augmented Reality

Abstract

There lies an opportunity for significant cost savings in the installation of subsea cables in offshore wind farms which is why the current work proposes a state-of-the-art method for monitoring the cable during installation. The proposed method enables offshore crew to look through the water with the use of augmented reality. To this end a real-time numerical model of the subsea cable dynamics is developed. The model is created in programming language C# and visualization in augmented reality is done using the game-engine Unity. This development environment is uncommon for engineering and scientific purposes and has been selected based on its ability to visualize model results in augmented reality, its extensive graphics library, its capability to process real-time in- and outputs and its free availability. Relevant physics are analyzed on contribution to global cable geometry and tension for the case of shallow water cable laying, resulting in an equation of motion which is sufficiently accurate for representing the physical phenomena occurring during cable lay. An assessment of the measurements required by the model during operation is made. The main challenge of modeling in real-time is that the average model time step is limited by available computational power, in turn limiting the axial stiffness range which can be modeled without the occurrence of numerical instability. Discretization is done using a lumped mass method. It is shown that cable dynamics can be modeled in real-time using an explicit method and that overcoming the associated limitation on axial stiffness does not lead to inaccurate results. The developed numerical solution is verified using OrcaFlex, which is typical software for dynamic analysis of offshore marine systems. An augmented reality interface is developed, including color codes indicating the structural state of the cable. The current work enables the visualization of the real-time model in augmented reality. Potential legal issues related to the implementation of augmented reality during offshore cable lay are outlined during a collaboration with Tilburg University. Successful practical implementation of the proposed innovation is associated with promising opportunities.