Development of a PID Control Strategy for a Compact Autonomous Underwater Vehicle

This paper presents a proportional-integral-derivative (PID) control strategy for navigation of a compact autonomous underwater vehicle (AUV) developed in-house. The AUV has a closed frame, neutrally buoyant, three-part modular structure made up of glass fibre composite material. Three fix position bi-directional thrusters are used for propulsion. A detailed CAD model of the AUV is developed using the modelling software SOLIDWORKS to estimate different system parameters. Hydrodynamic parameters are estimated from the ANSYS Fluent simulations of the AUV structure. Using the system parameters, a six degrees of freedom (DOF) dynamic model is developed, which is further simplified to a 4 DOF model. A 3D guidance system is developed for path planning using Line-of-Sight (LOS) strategy with way-point navigation. A closed loop PID controller is developed to follow the trajectory developed by the guidance system. The controller is simulated using MATLAB Simulink and the results are discussed.