On active control of marine vehicles with pneumatic compliances

Abstract

This paper is concerned with the use of pneumatic compliances to control the heave motions of semi-submersible marine vehicles when disturbed by ocean waves. The pneumatic compliances are in the form of open bottom ah tanks which are attached to the vessel at the water line and extend above and below the still water level. Each tank traps a volume of air above its internal water level. Active operation of these tanks involves controlling the amount of air trapped within the tanks, so as to exert varying forces on the vessel which can counteract wave induced disturbing forces. This paper describes a time domain dynamic analysis that is used to investigate the performance of active control. The vessel, its pneumatic compliances and control algorithms are also tested at model scale and results are compared with predictions from analysis.