Vessel azimuth control apparatus and azimuth control method

A vessel azimuth control apparatus comprising:

• an azimuth command generator that generates an azimuth command signal indicating an azimuth to which a vessel should travel;
• a yaw-angle detector that outputs a yaw-angle signal indicating a rotation angle around a vertical axis passing through a gravity center of the vessel;
• a yaw-angular-velocity detector that outputs a yaw-angular-velocity signal indicating a rotation angular velocity around the vertical axis passing through the gravity center of the vessel;
• a steering-angle detector that outputs a steering-angle signal indicating an angle of a rudder of the vessel;
• an azimuth controller that outputs a steering-angle command signal for making the vessel turn to the azimuth to which the vessel should travel, based on the azimuth command signal generated by the azimuth command generator, the yaw-angle signal outputted by the yaw-angle detector, and the yaw-angular-velocity signal outputted by the yaw-angular-velocity detector;
• a steering-angle controller that control a rudder, based on the steering-angle command signal outputted by the azimuth controller;
• and
• a control gain adjuster that calculates respective frequency responses of the yaw-angle signal and the yaw-angular-velocity signal to the steering-angle signal outputted by the steering-angle detector and then adjusts a control gain of the azimuth controller,
• wherein the azimuth controller includes
• a first control calculator that calculates a yaw-angular-velocity command signal for making an error between the azimuth command signal and the yaw-angle signal become zero,
• a second control calculator that calculates a feedback steering-angle command signal for making an error between the yaw-angular-velocity command signal calculated by the first control calculator and the yaw-angular-velocity signal become zero,
• a third control calculator that calculates a feed-forward steering-angle command signal, based on the yaw-angular-velocity command signal, and
• an adder that adds the feedback steering-angle command signal calculated by the second control calculator with the feed-forward steering-angle command signal calculated by the third control calculator and then outputs a steering-angle command signal.