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;
• a vessel-speed detector that outputs a vessel-speed signal indicating a vessel speed 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 has a calculation feasibility determinator for determining feasibility of calculation of frequency responses, based on the steering-angle signal, the yaw-angle signal and the yaw-angular-velocity signal, and that calculates respective frequency responses of the yaw-angle signal and the yaw-angular-velocity signal for the steering-angle signal outputted by the steering-angle detector, when the calculation feasibility determinator determines that calculation of frequency responses are feasible, and then adjusts a control gain of the azimuth controller.