Dynamic Positioning of Ocean Observation Platform under Current Disturbance

Firstly, the kinematic model under the current disturbance is established considering the special rotating-body shape of the small ocean observation platform. And a corresponding thrust distribution scheme is established for the annularly arranged propellers. After the construction of semi-physical simulation platform, the dynamic positioning process of the platform is simulated when the current magnitudes are different while the directions are the same, and when the current magnitudes are the same while the directions are different. The results show that the dynamic positioning of the platform can be completed under the current disturbance, and with a fast onset, an accurate positioning and a good control stability. Finally, the performances of position control and bow control are verified through pool tests designed for the ocean observation platform both in the static water and under the current disturbance. The results show that the ocean observation platform can complete the dynamic positioning with the expected precision. It is also found that the platform is more sensitive to the turning moment. In a separated bow control, the positioning can be achieved with only a small thrust, without any significant impact on the position control, because the platform is in a shape of a rotor. While in a position control, the platform needs to output a larger thrust because of the impact of the current and the shape. And in the latter case, once the propellers output the thrusts that aren't coordinated, the resulting additional turning moment will significantly affect the bow control.