• A brute-force spectral approach for wave estimation using measured vessel motions 

      Nielsen, Ulrik Dam; Brodtkorb, Astrid H.; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2018)
      The article introduces a spectral procedure for sea state estimation based on measurements of motion responses of a ship in a short-crested seaway. The procedure relies fundamentally on the wave buoy analogy, but the wave ...
    • AMOS DP Research Cruise 2016: Academic full-scale testing of experimental dynamic positioning control algorithms onboard R/V Gunnerus 

      Skjetne, Roger; Sørensen, Mikkel Eske Nørgaard; Breivik, Morten; Værnø, Svenn Are Tutturen; Brodtkorb, Astrid H.; Sørensen, Asgeir Johan; Kjerstad, Øivind Kåre; Calabrò, Vincenzo; Vinje, Bjørn Ole (Chapter; Peer reviewed, 2017)
      In order to validate relevant dynamic positioning (DP) control algorithms in a realistic environment, a full-scale DP test campaign, the AMOS DP Research Cruise 2016 (ADPRC’16), was organized in a collaboration between the ...
    • An Output Feedback Controller with Improved Transient Response of Marine Vessels in Dynamic Positioning 

      Skjetne, Roger; Sørensen, Asgeir Johan; Værnø, Svenn Are Tutturen; Brodtkorb, Astrid H. (Journal article; Peer reviewed, 2016)
      An output feedback controller for dynamic positioning (DP) of marine surface vessels is developed. The proposed algorithm has good performance during transients as well as good steady state performance. The method achieves ...
    • Comparing Controllers for Dynamic Positioning of Ships in Extreme Seas 

      Rabanal, Ole Maurice Røste (Master thesis, 2015)
      The primary purpose of this study is to develop two different dynamic position- ing (DP) controllers for a model-scale supply vessel Cybership III, and determine which control strategy provides a safer, smarter and greener ...
    • Comparing Controllers for Dynamic Positioning of Ships in Extreme Seas 

      Rabanal, Ole Maurice Røste; Brodtkorb, Astrid H.; Breivik, Morten (Journal article; Peer reviewed, 2016)
      This paper considers the design, implementation and experimental verification of two controllers for ship station keeping in extreme seas. In particular, the performance of two dynamic positioning controllers are compared, ...
    • Compensation of bias loads in dynamic positioning of marine surface vessels 

      Værnø, Svenn Are Tutturen; Brodtkorb, Astrid H.; Skjetne, Roger (Journal article; Peer reviewed, 2019)
      This paper investigates different methods for compensating the mean and slowly varying environmental loads, and unmodeled dynamics (bias loads) in dynamic positioning of marine vessels. Four different methods are compared; ...
    • Evaluation of Shipboard Wave Estimation Techniques Through Model-scale Experiments 

      Nielsen, Ulrik Dam; Galeazzi, Roberto; Brodtkorb, Astrid H. (Chapter, 2016)
      The paper continues a study on the wave buoy analogy that uses shipboard measurements to estimate sea states. In the present study, the wave buoy analogy is formulated directly in the time domain and relies only partly on ...
    • Evaluation of wave-frequency motions extraction from dynamic positioning measurements using the empirical mode decomposition 

      Garcia Rosa, Paula Bastos; Brodtkorb, Astrid H.; Sørensen, Asgeir Johan; Molinas Cabrera, Maria Marta (Chapter, 2019)
      For dynamic positioning operations, high-frequency wave induced motions cause excessive control action, and consequently additional power consumption and wear of actuators in the propulsion system. Thus, such operations ...
    • Hybrid Control of Marine Vessels: Dynamic Positioning in Varying Conditions 

      Brodtkorb, Astrid H. (Doctoral theses at NTNU;2017:351, Doctoral thesis, 2017)
      The next generation marine control systems will, as a step towards increased autonomy, have more automatic functionality in order to cope with a set of complex operations in unknown and varying environments, while maintaining ...
    • Hybrid controller concept for dynamic positioning of marine vessels with experimental results 

      Brodtkorb, Astrid H.; Værnø, Svenn Are Tutturen; Teel, Andrew R.; Sørensen, Asgeir Johan; Skjetne, Roger (Journal article; Peer reviewed, 2018)
      The next generation marine control systems will, as a step towards increased autonomy, have more automatic functionality in order to cope with a set of complex operations in unknown, challenging and varying environments ...
    • Hybrid Observer Combining Measurements of Different Fidelities 

      Brodtkorb, Astrid H.; Teel, Andrew R.; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2016)
      A signal-based hybrid observer combining measurements of different fidelities is proposed for position and velocity estimation of marine vessels. The concept assumes that noisy position measurements are available only ...
    • Hybrid observer for improved transient performance of a marine vessel in dynamic positioning 

      Brodtkorb, Astrid H.; Værnø, Svenn Are Tutturen; Teel, Andrew R.; Sørensen, Asgeir Johan; Skjetne, Roger (Journal article; Peer reviewed, 2016)
      Dynamic positioning (DP) systems are used on marine vessels for automatic station keeping and tracking operations solely by use of thrusters. Observers are key components of DP systems, and two main types are proposed in ...
    • Online wave estimation using vessel motion measurements 

      Brodtkorb, Astrid H.; Nielsen, Ulrik Dam; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2018)
      In this paper, a computationally efficient online sea state estimation algorithm is proposed for estimation of the onsite sea state. The algorithm finds the wave spectrum estimate from motion measurements in heave, roll ...
    • Response predictions using the observed autocorrelation function 

      Nielsen, Ulrik Dam; Brodtkorb, Astrid H.; Jensen, Jørgen Juncher (Journal article; Peer reviewed, 2018)
      This article studies a procedure that facilitates short-time, deterministic predictions of the waveinduced motion of a marine vessel, where it is understood that the future motion of the vessel is calculated ahead of time. ...
    • Sea state estimation using model-scale DP measurements 

      Brodtkorb, Astrid H.; Nielsen, Ulrik Dam; Sørensen, Asgeir Johan (Chapter, 2015)
      Complex marine operations are moving further from shore, into deeper waters, and harsher environments. The operating hours of a vessel are weather dependent, and good knowledge of the prevailing weather conditions may ...
    • Sea state estimation using multiple ships simultaneously as sailing wave buoys 

      Nielsen, Ulrik Dam; Brodtkorb, Astrid H.; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2019)
      The article presents initial ideas towards a network-based approach for sea state estimation used for marine operations and other maritime applications. In principle, all available means, ranging from in situ buoys, fleet ...
    • Sea State Estimation Using Quadratic Discriminant Analysis and Partial Least Squares Regression 

      Arneson, Ina Bjørkum; Brodtkorb, Astrid H.; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2019)
      This paper proposes non-model based sea state estimation methods for a dynamically positioned vessel. Sea state estimation entails finding the wave direction, significant wave height and peak wave period and is done based ...
    • Sea state estimation using vessel response in dynamic positioning 

      Brodtkorb, Astrid H.; Nielsen, Ulrik Dam; Sørensen, Asgeir Johan (Journal article; Peer reviewed, 2018)
      This paper presents a novel method for estimating the sea state parameters based on the heave, roll and pitch response of a vessel conducting station keeping automatically by a dynamic positioning (DP) system, i.e., without ...
    • Sensor-based Hybrid Observer for Dynamic Positioning 

      Brodtkorb, Astrid H.; Teel, Andrew R.; Sørensen, Asgeir Johan (Chapter, 2015)
      Observers are important components of dynamic positioning (DP) systems for marine vessels, estimating unmeasured states, filtering noise, filtering out wave induced motions, and predicting states in the case of signal loss. ...
    • Ship motion-based wave estimation using a spectral residual-calculation 

      Nielsen, Ulrik Dam; Brodtkorb, Astrid H. (Chapter, 2018)
      This paper presents a study focused on a newly developed procedure for wave spectrum estimation using wave-induced motion recordings from a ship. The particular procedure stands out from other existing, similar ship ...