The Arctic DP Research Project: Effective Stationkeeping in Ice

Skjetne, Roger; Imsland, Lars; Løset, Sveinung

doi:10.4173/mic.2014.4.1

Cited by 14 publications

(8 citation statements)

References 22 publications

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“…This works well for slowly varying forces, but when rapid and substantial force transients occur the control precision can be severely affected [3]- [5]. How to handle harsh and rapidly varying exogenous disturbances due to loads from sea-ice on a dynamically positioned vessel was the objective of the Arctic DP project [6] that initiated this study.…”

Section: Introductionmentioning

confidence: 99%

Disturbance Rejection by Acceleration Feedforward for Marine Surface Vessels

Kjerstad

Skjetne

2016

IEEE Access

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Acceleration signals have a powerful disturbance rejection potential in rigid body motion control, as they carry a measure proportional to the resulting force. Yet, they are seldom used, since measuring, decoupling, and utilizing the dynamic acceleration in the control design is not trivial. This paper discusses these topics and presents a solution for marine vessels building on conventional methods together with a novel control law design, where the dynamic acceleration signals are used to form a dynamic referenceless disturbance feedforward compensation. This replaces conventional integral action and enables unmeasured external loads and unmodel dynamics to be counteracted with low time lag. A case study shows the feasibility of the proposed design using experimental data and closed-loop high fidelity simulations of dynamic positioning in a harsh cold climate environment with sea-ice. INDEX TERMSMarine technology, Closed loop systems, Ice.

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Section: Introductionmentioning

confidence: 99%

Disturbance Rejection by Acceleration Feedforward for Marine Surface Vessels

Kjerstad

Skjetne

2016

IEEE Access

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“…Therefore, ice management ensures that ice loads on a protected vessel do not exceed its structural and operational safety limits [2]. Ice management relies on ice intelligence, which is the process of collecting and processing information about the ice environment [3], [4]. It is beneficial to collect this information in situ, without the need of external platforms such as satellites, drones, or buoys.…”

Section: Introductionmentioning

confidence: 99%

Ice Condition Assessment Using Onboard Accelerometers and Statistical Change Detection

Heyn

Blanke

Skjetne

2020

IEEE J. Oceanic Eng.

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The presence of sea ice is the predominant risk for ship operations in the Arctic, and monitoring of ice condition around a vessel is crucial during all times of operation. This paper presents a system for online onboard assessment of ice condition. It is demonstrated that ice-induced accelerations in the bow section of the hull follow a bivariate t-distribution and that parameters of the distribution have a one to one relation to ice condition. The paper suggests a methodology to monitor the ice condition in real time through estimation of parameters that characterise the distribution of hull accelerations. It is shown how a Kullback-Leibler divergence measure can classify ice condition among a set of pre-trained conditions. An absolute measure of ice load is suggested as an alternative for situations when pre-training data are not available. The alternative algorithm quantifies the condition through the entropy of measured accelerations. The article presents a computationally easy methodology and tests against data collected during Arctic transit of an icebreaker. Further, the classification results are compared with the results from two standard methods from machine learning, decision tree and a support vector machine approaches. The results show that the statistical methods provide robust assessment of the prevailing ice conditions, independent of visual and weather conditions. The also comparison shows that the statistical classification methods, designed by process knowledge, provide steadier and more reliable results.

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“…The recently completed project "Arctic DP: Safe and green dynamic positioning operations of offshore vessels in an Arctic environment" investigated various aspects of cold-climate DP operations and published the main findings in a special edition of the MIC journal, see (Skjetne et al, 2014).…”

Section: Dynamic Positioning Everywherementioning

confidence: 99%

From Eureka to K-Pos: Dynamic Positioning as a Highly Successful and Important Marine Control Technology

Breivik¹,

Kvaal

Østby

2015

IFAC-PapersOnLine

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Dynamic positioning (DP) started out as an exotic control technology for geological core sampling in deep waters in the early 1960s. The technology gradually became more advanced during the 1970s, especially after it was introduced and applied in the offshore petroleum industry. Several British, French and US companies delivered DP systems during this period, and DP controllers were typically based on the PID principle. In 1977, the first DP system applying modern control theory in the form of a Kalman filter was delivered. This system was a collaborative effort between key companies, research institutes and universities in Norway, motivated by the discovery of oil and gas on the Norwegian continental shelf in 1969. A small group called Albatross had been established as part of the state-owned "modernization locomotive" Kongsberg Våpenfabrikk to industrialize and deliver the new DP system. Albatross DP rapidly gained popularity, and in 1980 all DP systems in the world were delivered by this small group situated in the small Norwegian inland town of Kongsberg. Since then, what has later become known as the Kongsberg DP has been able to maintain a majority share of an increasingly large DP market. Today, dynamic positioning technology has developed from scientific to industrial to massmarket applications, and has been a cornerstone of the offshore petroleum industry for more than four decades. This paper will present DP as an example of a highly successful and important marine control technology, and use the Kongsberg DP as a case study to illustrate key factors required to achieve commercial success for control applications. The paper is based on the book "The Jewel in the Crown: Kongsberg Dynamic Positioning Systems 1975 -2015", which was released in June 2015.

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The Arctic DP Research Project: Effective Stationkeeping in Ice

Cited by 14 publications

References 22 publications

Disturbance Rejection by Acceleration Feedforward for Marine Surface Vessels

Disturbance Rejection by Acceleration Feedforward for Marine Surface Vessels

Ice Condition Assessment Using Onboard Accelerometers and Statistical Change Detection

From Eureka to K-Pos: Dynamic Positioning as a Highly Successful and Important Marine Control Technology

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