Motion Control of Underwater Vehicle Floating in Space under Ice Cover

The subject of the paper is the control of vertical motion of the underwater vehicle operation under ice cover. Underwater vehicles are usually controlled by planes and/or by water ballasting using a compensating tank. But, taking into account the very low allowed operation speed of underwater vehicles near ice cover, ballasting remains the mostly effective way of control. The vertical motion is influenced by the vehicle’s residual buoyancy which depends on two variables: (1) a pressure hull volume reduction depth-wise, (2) seawater density variation depth-wise, as well as (3) a vertical force impulse induced by an unexpected contact with ice cover. The control of vertical motion of the vehicle may be done better by use of seawater density current information, which enhances the reliability and controllability of underwater vehicle maneuvering. Also the information on a vertical distance to ice cover and a corresponding vertical velocity shall be used for reduction of the vehicle vertical speed, i.e. for diminution of ice contact force impulse. So, the instrumentation for the underwater vehicle for seawater density metering and also for measuring of vertical distance to ice cover is very useful for effective motion control of underwater vehicle The control laws for the compensating tank ballast control are developed in the paper. To demonstrate the advantages of the developed control method, a computer simulation of underwater vehicle vertical maneuvers under ice cover is performed.