Simulation of Fuzzy Sliding-Mode Control for AUV Pitch Control

In the process of diving, the pitch control is the key point to an AUV's motion control in vertical plane. So far, different control strategies are adopted, and it is difficult to control due to non-linearities of the vehicle dynamics and model uncertainties. Based on the nonlinear model of AUV in vertical plane, the paper established a mathematical model of AUV's pitch motion in vertical plane by linearizing the model at a specified operating point. A fuzzy sliding-mode controller was designed to adjust the control gain in a switch control mode. The controller was applied to control the AUV's pitch motion with the disturbance of ocean current. The computer simulation demonstrated that this proposed controller was effective to the AUV's uncertain model. The system showed a speedness and robustness under some external disturbances, and was effective to eliminate system chatting.