Design of Submarine near-surface depth controller

A Submarine is mainly disturbed by the first-order and second-order wave force during voyaging near surface, which results in unstable movements when no control is applied to the Submarine. For concealment, the Submarine is required to control its depth. For the target, a two-step depth fuzzy controller is designed. The controller, by adding a node of modifying control amount to the routine control rule, realized a self correct function. GA is used to optimize control parameters. A two-step fuzzy controller is used to produce stern angle to counteract second-order wave force. The inputs are second-order wave force and moment; the output is wave stern angle. Total stern angle is the sum of wave stern angle and stern angle that was the output of previous depth controller. Simulation indicates that this fuzzy controller has a comparatively stable control effect. The Submarine can navigate according to the anticipant depth and arrive at stability at last.