An experimental validation of an icevaning control algorithm for an Arctic offshore vessel in managed ice condition

Abstract

A new approach to icevaning control for Arctic offshore vessels has been developed in this study. The icevaning action of an Arctic offshore vessel is regarded as a promising control strategy for reducing external forces caused by ice floes around its hull. However, it is difficult to figure out the external condition such as ice thickness, ice drifting speed and direction due to the difficulties in measuring and monitoring ice floes in real time. Therefore, icevaning control algorithm without explicit measurement and observation on the external forces is developed in this study. In order to realize the icevaning action, a task space concept, which is widely applied in the field of robotic arm control, is utilized. The icevaning controller is designed in the task space which is associated with the surge and sway motion around a virtual pivot point of a vessel, and separated from the yaw motion in the null space. Thus, the icevaning action can beperformed with no need for explicit disturbance observation and measurement in sea ice condition. In order to secure the stability of the icevaning control action, a backstepping technique based on the Lyapunov stability theory is applied.A set of experiments is conducted to show the performance of the icevaning control algorithm.