Design of Hybrid Controller for Dynamic Positioning.pdf

Design of Hybrid Controller for Dynamic Positioning from Calm to Extreme Sea Conditions○ Trong Dong Nguyen*a , Asgeir J. S?rensenb, and Ser Tong Queka ○ This paper has not been presented at any IFAC meeting. * Corresponding author. Email address: trong.d.nguyen@ntnu.no, Phone: +47 a Department of Civil Engineering, National University of Singapore, E1A-02-19, 1 Engineering Drive 2, Singapore 117576. b Department of Marine Technology, Norwegian University of Science and Technology, Otto Nielsens Veg 10, NO-7491 Trondheim, Norway. Abstract High level control of dynamic positioning systems on marine vessels using hybrid controller are developed to extend the operational weather window for marine operations to harsh environments. The types of hybrid controller considered are multi-output PID controllers with position measurements, and multi-output PID and acceleration feedback controllers with position and acceleration measurements. Numerical simulations and experiments in addition to stability proof are conducted to verify the proposed hybrid-controller dynamic positioning system in varying environmental conditions from calm to ex- treme seas. Key words: hybrid controller, dynamic positioning, marine vessels, extreme conditions. 1. Introduction The depletion of oil and gas in shallow waters and their higher demand in recent years has led to the use of dy- namically positioned (DP) floating structures for offshore exploration and exploitation of hydrocarbons. DP systems keep floating structures in fixed position or pre-determined track for marine operation purposes exclusively by means of active thrusters. Although there may be the risk for so- called drive-off or drift-off causing possible damages, DP vessels can operate with high positioning accuracy, and are flexible and cost-effective in operation; especially in deep water or where there is limited room for anchors on the seabed. In the 1960s, t