J.B. van den Berg
- Thruster allocation for dynamical positioning
- 72nd European Study Group Mathematics with Industry (SWI 2010), Amsterdam, the Netherlands
- Book/source title
- Proceedings of the 72nd European Study Group Mathematics with Industry
- Pages (from-to)
- Amsterdam: CWI
- Document type
- Conference contribution
- Faculty of Science (FNWI)
- Korteweg-de Vries Institute for Mathematics (KdVI)
Positioning a vessel at a fixed position in deep water is of great importance when working offshore. In recent years a Dynamical Positioning (DP) system was developed at Marin . After the measurement of the current position and external forces (like waves, wind etc.), each thruster of the vessel is actively controlled to hold the desired location.
In this paper we focus on the allocation process to determine the settings for each thruster that results in the minimal total power and thus fuel consumption. The mathematical formulation of this situation leads to a nonlinear optimization problem with equality and inequality constraints, which can be solved by applying Lagrange multipliers.
We give three approaches: first of all, the full problem was solved using the MATLAB fmincon routine with the solution from the linearized problem as a starting point. This implementation, with robust handling of the situations where the thrusters are overloaded, lead to promising results: an average reduction in fuel consumption of approximately two percent. However, further analysis proved useful. A second approach changes the set of variables and so reduces the number of equations. The third and last approach solves the Lagrange equations with an iterative method on the linearized Lagrange problem.
- Voor zover bekend, is dit alleen gepubliceerd als interne publicatie van het CWI.