Session: 06-08-02 Model Tests

Submission Number: 157424

Wave Tank Test of a DP Drilling Ship Model With Active Environmental Force Emulation 

Model testing is essential to understand the behavior of physical phenomena and, therefore, to develop and validate mathematical models. In this paper, we analyze small scale model tests of a DP drilling ship (length 2.75m, scale 1:80), subject to environmental forces (wave, wind and current). We present a hybrid model test setup, where the vessel is tested in a 14m x 14m wave tank with 148 active wave generators. The wind and current effects are emulated using four force actuators attached to the model. The actuators consist in servomotors controlling the force in lines attached to the vessel, and, together, they apply the desired force and moment in the horizontal plane (surge, sway and yaw). The drilling ship model has 6 azimuthal thrusters and a DP system with Bias and Weathervane functions. First, the force actuator system was tested with a six degree-of-freedom load cell, where the controller (super-twisting sliding mode control) and force allocation algorithm were validated. The system is able to produce forces of up to 5 N, wih a maximum frequency of 2 Hz and accuracy of 99 %. Then, we did decay tests of the vessel, with the four forces actuators connected, to measure the force controller capacity to compensate movement disturbances. The results indicated that the forces actuators did not affect natural periods of the vessel and only slightly increased damping. Finally, we did a final validation of the complete setup, with station keeping tests of the vessel subject to wind, wave and current.

Presenting Author: Pedro C. De Mello University of São Paulo / Numerical Offshore Tank Laboratory (TPN-USP)

Presenting Author Biography: Pedro C. de Mello was born in São Paulo, Brazil, in 1976. He received his B.S degree in electrical engineering from São Paulo State University (UNESP), Ilha Solteira, in 2002, his M.S. degree in oceanic engineering from the Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, in 2006, and the Ph.D. degree in mechatronic engineering from the University of São Paulo (USP), São Paulo, in 2012. From 2004 to 2005, he was a Researcher in the LabOceano ocean basin at UFRJ. Since 2006, he has been a researcher in the Numerical Offshore Tank at the University of São Paulo. Since 2012, he has been the wave basin coordinator of the Numerical Offshore Tank at the University of São Paulo. From 2017 to 2018, he was an Assistant Professor of the Naval and Oceanic Engineering Department, at the University of São Paulo, and this year, 2025, he became a Professor of that department.