Arctic DP: Safe and Green Dynamic Positioning Operations of Offshore Vessels in an Arctic Environment

The KMB project Arctic DP investigates safe and efficient offshore operations in the Arctic that includes dynamic positioning (DP) of offshore vessels in ice. The Project performs research along 3 main axes: A) Mathematical models and algorithms for compensation of ice loads in a DP control system. B) Numerical simulators of floating vessels in ice. C) Monitoring methods and estimation algorithms for online acquisition of sea-ice data. As part of Activity A) we are considering 3 strategies for compensation of sea-ice loads on a DP vessel: i) Development of a characteristic mathematical model for global ice loads that makes it possible to use existing onboard sensors to estimate the loads and compensate by feedback control. This is a reactive control strategy that does not need a physically redesigned DP control system (only SW update). ii) Use of accelerometer measurements in the vessel to directly calculate the corresponding ice forces and compensate these by feedforward control - also a reactive control strategy. iii) Development of a supervisory system that monitors the ice situation and gives predictive estimates of the ice loads on the vessel forward in time. This results in a proactive control strategy where the DP system will be able to forecast the future trends of the ice forces, such that automatic countermeasures can be prepared earlier and actuated more precisely. Development of such a system is a major task. It requires both good models of how sea-ice and a DP vessel interact, and an extensive measurement network to continuously monitor a large operations area. Such a control strategy will also enable a major shift in how to conduct a DP operation in an ice-infested area versus DP in open water. The research activities B) and C) supports development of such a proactive system. In activity B) we work on various types of ice simulators. Development of detailed simulation tools is important and has many applications, among others to predict the ice load trends on a vessel, as a design tool for Arctic vessels, planning of operations, DP-Ice capability analyses, operational decision support, and training of crew. Many publications have been produced by the project on such simulation technology, where i.a. Ivan Metrikin received the "OMAE 2012 Best Paper of Polar and Arctic Sciences and Technology Symposium". In activity C) we investigate the use of autonomous underwater vehicles for subsea acquisition of sea-ice data, use of aerial drones to monitor the sea-ice from above, and use of image processing techniques to extract relevant information from ice images taken from the air. The project has so far produced 35 publications at international per-reviewed conferences, 15 published (and 3 in review) journal articles, and several software packages for simulation of vessel responses in sea-ice and ice imaging software toolbox. The project has received extensive international recognition through keynote lectures at international academic and industrial workshops and conferences. Please refer to the Special Edition on the Arctic DP project in the journal MIC (Vol.35, No.4) for scientific information: http://www.mic-journal.no.

It is an expressed need of the industry to strengthen the competences of the Norwegian maritime industry in arctic marine operations with special focus on dynamic positioning (DP). The objective of this KMB is to enable future systems for DP in arctic env ironments to be automatic control systems. The control system must construct an accurate picture of the vessel's and the environment's situation, combining measurements with models in an observer, and it must act on this information safely using automatic feedback control. However, in designing such control systems, it is vital to have a good understanding of the the vessel and its hydrodynamics and the disturbances that influence the dynamic behavior of the vessel (ice; in addition to waves, wind, curren t). In overall there are two main research objectives of the research; (1) to understand and build competence on the effects of ice loads on DP vessels through modeling and simulation, and (2) to carry out mathematical control designs that targets import ant aspects for safe commercial systems. These objectives are further translated into 4 proposed PhD themes of research: PhD#1: Modeling, supervisory control, and simulation of DP vessels in varying arctic conditions. PhD#2: Observer schemes for DP opera tion in arctic conditions. PhD#3: Adaptive and optimal feedback control designs for DP operation in arctic conditions. PhD#4: Development of fault-tolerant DP control designs and operational procedures for safe DP operations in arctic conditions. In orde r to achieve the goals, a multidisciplinary team is established by 4 key researchers (professors) from 3 departments at NTNU together with the the industrial partners Kongsberg Maritime, DNV, and StatoilHydro. When these leading industrial partners combin e forces with NTNU on the topics of this KMB, they clearly make a statement for the potential of this research. In addition, research synergy will be established with several research centers, CeSOS in part