Active Control of Dynamic Platforms

The safety and performance of offshore operations are significantly affected by waveinduced disturbances. For example, it is very hazardous to transfer load or personnel between a fixed and a moving platform, or between two moving platforms, in adverse weather conditions. The use of a dynamic platform which is controlled to remain stationary irrespective of base induced motion and payload changes would allow maximum operation and improved safety. Therefore such a platform could be used (1) to address the current offshore load transfer problems in adverse weather condition, (2) as a helicopter landing platform, (3) as support platforms when a large structure is transported using more than one vessel, or (4) incorporated with a gangway system when there is a relative motion between two decks; this will allow the synchronisation of the docking end of the gangway with the motion of the respective deck. This research was focused on the investigation of a modelling framework and control schemes for dynamic platforms taking into account practical issues. The key objective was to control a platform to remain stationary irrespective to external disturbances. Two platform systems have been applied to show the efficiency and relevance of the proposed modelling framework and control schemes, which are based on differential geometrical methods. Good simulation results have been obtained.