Abstract: “In this paper a transfer function of submarine and steering gear are defined. Transfer functions have been analyzed and mathematical model of the system is presented. Optimal controller and its parameters are found using simulation of the whole system by Matlab and Simulink. Optimal parameters have been confirmed applying Parseval’s theorem. Different types of controllers: P, PI and PID are analyzed. Responses for the whole system to the unity step function are given. To determine the stability of the system, analytical and graphical methods were used. A nonlinear system was also considered with two nonlinear elements to protect a steering gear from the huge signals. Further research for improvement of the model, including a certain disturbance is suggested.”

Keywords: Submarine, optimal depth control, Parseval’s theorem, Simulink, nonlinear system