Transient hydrodynamics coefficients analysis of a six-degree-of-freedom underwater manipulator

• Published in: Ocean engineering Vol. 312; p. 119156
• Main Authors: Wang, Xingyao, Liu, Yanjun, Xue, Gang, Bai, Fagang, Huang, Shuting
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.11.2024
• Subjects: CFD; Six degrees of freedom; Transient hydrodynamics; Underwater manipulator; CFD; Underwater manipulator; Six degrees of freedom; Transient hydrodynamics
• ISSN: 0029-8018
• DOI: 10.1016/j.oceaneng.2024.119156

The transient hydrodynamic characteristic of a multi-degree-of-freedom (multi-DOF) underwater manipulator is a significant and complex issue that can directly affect the accuracy and precision of the motion trajectory prediction and control. In this paper, the transient hydrodynamic loads of a six-DOF manipulator at different angular velocities and angular accelerations are obtained using computational fluid dynamics (CFD) simulation. The transient hydrodynamic coefficients are normalized by the distance of the arm centroid and an approximation function on the coefficients is obtained. The comparative analysis of the simulation data shows that both the shape and relative motion between the joints determine the transient hydrodynamic coefficients. The fitted function can simply and fast calculate the hydrodynamic loads and hydrodynamic coefficients by the input kinematic parameters. The accuracy of the function is about 94.8% which is acceptable for control engineering applications. This study can deepen the cognition of the transient hydrodynamic process of the multi-DOF underwater manipulator and the proposed approximation function can improve the control precision and accuracy in practical underwater operations. •The CFD method is used to obtain the transient hydrodynamic forces.•The influence of joints' relative motion on hydrodynamic coefficients is analyzed.•An empirical formula for the drag coefficient is obtained.