Full Content is available to subscribers

Subscribe/Learn More  >

A Generic Optimization Algorithm for the Allocation of DP Actuators

[+] Author Affiliations
E. F. G. van Daalen, J. L. Cozijn

Maritime Research Institute Netherlands (MARIN), Wageningen, The Netherlands

C. Loussouarn

Ecole Polytechnique, Palaiseau, France

P. W. Hemker

Centrum Wiskunde & Informatica (CWI), Amsterdam, The Netherlands

Paper No. OMAE2011-49116, pp. 87-94; 8 pages
  • ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering
  • Volume 1: Offshore Technology; Polar and Arctic Sciences and Technology
  • Rotterdam, The Netherlands, June 19–24, 2011
  • ISBN: 978-0-7918-4433-5
  • Copyright © 2011 by ASME


In this paper we present a generic optimization algorithm for the allocation of dynamic positioning actuators, such as azimuthing thrusters and fixed thrusters. The algorithm is based on the well-known Lagrange multipliers method. In the present approach the Lagrangian functional represents not only the cost function (the total power delivered by all actuators), but also all constraints related to thruster saturation and forbidden zones for azimuthing thrusters. In the presented approach the application of the Lagrange multipliers method leads to a nonlinear set of equations, because an exact expression for the total power is applied and the actuator limitations are accounted for in an implicit manner, by means of nonlinear constraints. It is solved iteratively with the Newton-Raphson method and a step by step implementation of the constraints related to the actuator limitations. In addition, the results from the non-linear solution method were compared with the results from a simplified set of linear equations, based on an approximate (quadratic) expression for the thruster power. The non-linear solution was more accurate, while requiring only a slightly higher computational effort. An example is shown for a thruster configuration with 8 azimuthing thrusters, typical for a DP semi-submersible. The results show that the optimization algorithm is very stable and efficient. Finally, some options for improvements and future enhancements — such as including thruster-thruster and thruster-hull interactions and the effects of current — are discussed.

Copyright © 2011 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In