On the Presence of Nonlinear Oscillations in the Teleoperation of Underwater Vehicles under the Influence of Sea Wave and Current

The contribution of this paper is the study of nonlinear oscillations of remotely operated vehicles (ROVs) subject to strong currents and harmonic waves when the vehicle is servocontrolled around a fixed position. A complete model for quasi-stationary dynamics of a ship-cable-ROV system was developed. A high-performance control system was designed, in which the cable force is calculated on the basis of measured end positions. Our analysis reveals that the ROV behavior can transit from period one to chaos without the thrusts enter saturation zones. This feature appears more marked as long as the cable stiffness increases. In view of recent results, one can broadly say that the cable elasticity acts as a suppressor of the complete subspectrum of subharmonics in the vehicle dynamics, and simultaneously, as an effective attenuator of its superharmonics.