A motion tracking approach to position marine floating structures based on measured acceleration and angular velocity

One of the major challenges arising from dynamic response measurement of floating structures is to effectively track their 6DOF response in harsh environments. Although the combination of GPS and INS techniques has the ability to estimate the positioning of floating structures, it is tedious that the corrections of response measurements have to be carried out at regular intervals due to the low accuracy, instability and various harsh environments. Aiming at achieving long-term stable and efficient measurements of floating structural responses, a motion tracking approach based on the combination of the accelerations and angular velocities has been proposed in this paper. First, a novel displacement reconstruction model has been established to effectively determine the translational displacements of floating structures. Following that, to correct the errors of tilt and coordinate data from the measured accelerometers, the quaternion method has been applied to update the dynamic Euler angle. The major contributions of this research include: (1) the development of a non-integral drift-free method for displacement reconstructions without GPS and (2) the realization of a synchronous tracking system considering dynamic tilt error of accelerometers for floating structures with the motions in 6-DOF. To demonstrate the correctness of the proposed approach, two numerical examples have been examined to track the motion of floating structures. Numerical results have shown that the maximum error of the reconstructed displacement between the proposed approach and Orcaflex is only 0.8096%, indicating their good agreement. Then, a physical experiment of a semi-submersible platform under the action of regular and irregular waves has been conducted to verify the feasibility of the developed tracking approach by comparison of the data from the traditional optical device and camera. The results show that the proposed method has the ability to effectively predict the operation conditions of floating structures and provides a valuable insight into the development of an efficient synchronous tracking system for various engineering applications.