Dynamic Modeling And Control Of Complex- Shaped Remotely Operated Vehicles

The application of remotely operated vehicles(ROVs)for deep-sea exploration and exploitation has been increasingly rising.The performance of control system and dynamic modeling of ROVs are essential for ROVs to achieve both high efficiency and quality of underwater operations and hence high-fidelity dynamic models are required to conduct control system design.However,it is difficult to establish accurate dynamic model due to complex shape of most of ROVs.Firstly dynamic modeling of complex-shaped underwater vehicle is studied in this paper.Hydrodynamic coefficients of a ROV of complex shape,DOE HD2+2,are calculated by computation fluid dynamics(CFD).The added mass matrix and damping matrix in 6 degrees of freedom are obtained,in addition to dynamic model of thruster.The dynamic model of DOE HD2+2 ROV is then built.Secondly the motion control system is designed based on the established dynamic model.A robust control design method based on disturbance observer is presented.The disturbance observers that estimate external disturbance force/torque,and slide mode controllers that control both the height and heading of ROV are developed.Finally both nonlinear simulations and tank experiments are carried out to verify the performance of control system.Experimental results show that the control system has a much better performance over the exiting PID control system which were developed by trial-and-error approach.Therefore the validity of ROV dynamic model based on CFD calculation is verified indirectly.