Published on September 2019 | Underwater Vehicle Dynamics, Marine Hydrodynamics , Control Systems

Study of control system and flow analysis of an autonomous underwater vehicle

An underwater vehicle is used for various purposes like ocean exploration, data collection, military applications, environment monitoring etc. Underwater vehicles are mainly sub classed into manned and unmanned vehicles. Remotely operated vehicle and Autonomous underwater vehicle are two types of unmanned vehicles. An autonomous underwater vehicle is one that travels underwater without any input. It needs to be preprogramed and main advantage is that degree of human intervention will be less. Various types of controllers like P-Type, PI-Type, PID-Type, Sliding mode controller etc. are being used for altering the dynamics of a system. In this study sliding mode controller is selected because of its various advantages over other controllers. The motion along diving plane (vertical) is considered and along heading plane (horizontal) is not taken into account. The motions considered in this study are heave velocity and pitch movement along with heave forces. Simulation is done using MATLAB by modifying an existing code replacing the various factors like hydrodynamic coefficients, weight, buoyancy, geometric centres etc. of a new AUV. The design of an existing AUV is made using Catia and is used for flow analysis using Ansys (fluent). The results obtained such as heave rate, pitch rate, pitch angle, depth and plane angles as a function of time are reported. The response of the controller to the commanded depth is also analysed and reported in this paper.