Fuzzy Logic Application for Underwater Robot with Undulating Fin Control

Abstract

This paper presents the development and analysis of control algorithms for an autonomous underwater vehicle (AUV) equipped with an undulating fin propulsor. A brief review of existing studies on dynamic and kinematic models of underwater robots with flexible fins is provided. A mathematical model of the vehicle interacting with the environment is implemented in the Simscape-MATLAB framework. To solve the problem of depth and course control, the Active Disturbance Rejection Control (ADRC) method is applied. This approach extends the system model by introducing an additional state variable that represents factors not included in the mathematical description. The virtual state is estimated online by an observer and is used to generate the control signal, which makes it possible to compensate for external disturbances. In addition, fuzzy logic methods based on physical and hydrodynamic principles as well as expert knowledge are used to transform generalized control actions into meaningful fin-motion parameters. The advantage of the proposed approach is that it does not require an exact analytical model of AUV dynamics, especially the relationship between fin kinematics and vehicle motion. Simulation results under rapidly varying external disturbances confirm the effectiveness of the proposed mathematical model and control strategy.