Patent ID: 8567331

Claim:
A method for roll stabilization using feedback applied to the rudder of the ship, comprising the steps of: obtaining output from a roll angle sensor; inverting the output; comparing the inverted output to the output of a multiple-feedback-path nonlinear dynamic compensator (NDC), producing thereby a first signal, wherein the NDC provides absolute stability for rudder angle and rudder rate saturation; inputting the first signal to a roll compensator; comparing a chosen heading to output from 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.