A Robust Adaptive Interval Type-2 Fuzzy Control for Autonomous Underwater Vehicles

Autonomous Underwater Vehicles (AUVs) have attracted a lot of interest in recent years as a tool to perform various underwater tasks in both civilian and military sectors. As AUVs' dynamics are highly nonlinear, complex, and time-varying, several studies have been conducted to develop an adaptive control based on the intelligent control techniques. This paper proposes an adaptive interval type-2 fuzzy controller (AIT2FC) for an AUV. An AIT2FC is designed to control the position of the vehicle in the XY and XZ planes, namely, surge, pitch, and yaw motions. The adaptation law of the interval type-2 fuzzy consequent parameters is derived based on the sliding mode control (SMC) theory. The adaptive fuzzy controller has been implemented successfully in an AUV to reach the desired trajectory. Simulation results show that better performance was achieved using AIT2FC compared to a fixed fuzzy controller. The robustness of the proposed controller was investigated against external disturbances.