Depth control of an unmanned underwater vehicle with two degree of freedom using fuzzy sliding mode control

Unmanned underwater model is a non-linear system that various methods have been proposed for the depth control. Sliding mode control (SMC) is a state feedback robust control for non-linear systems that will change its structure to achieve optimal performance. In this method, it is assumed that the process control can be instantly changed from one structure to another structure. In classic SMC, Computational delays and restrictions on operators leads to the phenomenon of chattering in control signal. In this paper, depth control of an unmanned underwater vehicle system of two degrees of freedom is considered. It is shown that the use of the sliding mode controller for the depth controlling of the system under study, will lead to the chattering phenomenon. To solve the problem for the system under study, there is tried to use the fuzzy sliding mode control. Simulation results indicates that the fuzzy sliding mode method is solved the problem in which the system properly is controlled with low chattering control signal.