Depth control of pipeline inspection AUV based on fuzzy sliding mode control

Addressing the depth control challenge of Autonomous Underwater Vehicles (AUVs) for submarine pipeline inspection during the entire process from release from the surface mother ship to the seabed landing point, this paper proposes a depth control strategy based on fuzzy sliding mode control (FSMC). According to the dynamic characteristics of the AUV at different speed stages, the motion process is divided into three phases: high speed, medium speed, and low speed, corresponding to three control modes: horizontal rudder alone, combined rudder and thruster, and vertical thrusters alone. Sliding mode controllers (SMC) are designed for each mode, and fuzzy logic is introduced to optimize the sliding mode parameters in real-time, forming fuzzy sliding mode controllers. Simulation results demonstrate that the proposed method achieves precise depth control across all stages. The FSMC exhibits superior performance in response speed and overshoot suppression compared to the conventional SMC, validating its effectiveness and robustness for practical pipeline inspection missions.