Simulation and Controller Design of an Underwater Vehicle

Autonomous Underwater Vehicles (AUVs) have become popular around the world in recent years. They are used for a variety of purposes in marine environments, including scientific research, ocean mapping, environmental monitoring, and military applications. Their main purpose is to operate the underwater vehicle autonomously without requiring a human pilot, which allows them to collect data in dangerous or difficult-to-reach areas, operate for extended periods of time, and cover large areas of the ocean. In this paper, we constructed a simulation block for underwater vehicles using MATLAB Simulink tools. The equations and parameters of the MIT Autolycus are used for simulation and analysis. First, the step responses are checked to see the correctness of the model. Then the linear models for the pitch and yaw motions are obtained using identification tools in Simulink using the step responses from the nonlinear model. A 2-degree-of-freedom PID controller is designed, and the performance and stability margins of the control loops are analyzed. It is found that both controllers have big gain margins and 45-degree phase margins. The bandwidth of the pitch control loop and yaw control loops are 4 rad/s and 0.3 rad/s, respectively. Both step responses show that the steady-state errors and maximum overshoot are very small.