THE ANALYSIS OF THE CONTROL OF ACTIVATED ANTI-ROLL TANKS.
ILLINOIS STATE NATURAL HISTORY SURVEY URBANA
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The application of activated, anti-roll tanks is considered in detail. Particular attention is paid to the configuration and the design of the control system to actuate the tank. In the first sections, the equations of motion of the ship, tank and pumps as well as the forces created by the seaway are derived. The methods of selecting the control are then discussed and the techniques of solving both the linearized and the full, non-linear equations are presented. Using these analysis techniques, it was determined that the active tank control could best be selected on the basis of minimizing the response of the ship to an impulsive roll velocity. The control systems so selected were used to estimate the roll reductions in various sea states of three typical type ships. It was shown that the active tank is significantly better in reducing the roll of the ship than the ordinary passive anti-roll tank. With proper design, it is shown that this can be accomplished without extremely large horsepowers. The non-linear studies conducted showed that the effects of saturation of the tank were to significantly degrade the tanks performance. Finally, a technique for choosing an optimum controller using Liapounov theory is outlined. Author
- Marine Engineering