Rudder roll stabilization by nonlinear dynamic compensation
AssigneeUniversity of Wyoming
InventorJohn F. O'Brien
Life of this patent
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Abstract
A method for rudder roll stabilization having two-feedback-path nonlinear dynamic compensation (NDC) is described. The high-order, Nyquist-stable control system having NDC hereof is absolutely stable and will provide a 20%-40% improvement in performance over existing roll reduction designs when lower performance steering mechanisms are employed, and is superior to linear controllers. That is, the present invention will be effective rudder roll stabilization in commercial vessels having slower rudders as well as in vessels having steering machines representing the best performance currently available, such as military systems. Since no ship hardware modifications are required, the present roll control technology will be able to be economically implemented.
Claims7
A method for roll stabilization using feedback applied to the rudder of the ship, comprising the steps of:
- comparing the inverted output of a roll angle sensor to the output of a multiple-feedback-path nonlinear dynamic compensator (NDC), producing thereby a first signal;
- inputting the first signal to a roll compensator;
- comparing a chosen heading to the output of a heading sensor, producing thereby a heading error signal;
- inputting the heading error signal into a heading compensator;
- adding the outputs of the heading compensator and the roll compensator, producing thereby a second signal;
- inputting the second signal into a rudder steering controller, thereby generating a rudder angle command signal;
- and
- simultaneously inputting the second signal into the NDC;
- whereby, the output of the NDC is zero if the rudder angle command signal does not exceed either limitations to the rudder angle or to the rudder rate of movement.
Dependencies are inferred from the claim text.