Design and Implementation of Fuzzy Logic Controller for Autonomous Underwater Vehicle

Abstract: The objective of this study is to design a fuzzy logic controller (FLC) for Autonomous Underwater Vehicle (AUV) model for controlling the Pitch and Depth. In this process, fuzzy controllers are designed and implemented for controlling the AUV in the depth plane. Subsequently the controller performance is evaluated in the presence of dynamics of complete model maneuverings. AUV dynamics have been derived under various assumptions on the motion of the vehicle. Plant transfer function is extracted from the hydrodynamic coefficients. Fuzzy logic controller (FLC) using Sugeno type fuzzy inference system is employed with minimal number of rules for Pitch and Depth control. The FLC based on fuzzy logic provides a means of converting a linguistic control strategy based on expert knowledge into an automatic control strategy. In Pitch control FLC inputs are error and error rate, in depth control FLC inputs are error, pitch rate and pitch. This study also involves the design of conventional P and PD controller for comparing performance of FLC. The simulation results show the better performance by applying proposed control strategy. MATLAB control tool box is used for design, implementation and simulation.

Keywords: Autonomous underwater vehicles, Six Degrees of Freedom, Conventional controller, Fuzzy Logic Controller, Depth control.