Heading control of an underwater vehicle using dynamic fuzzy sliding mode controller

A novel dynamic fuzzy sliding mode control (DF-SMC) algorithm is developed for heading angle control of autonomous underwater vehicles (AUV´s) in horizontal plane. So far, the dynamics of AUV´s are highly nonlinear, time varying and hydrodynamic coefficients of vehicle are difficult to be accurately estimated a prior, because of the variations of these coefficients with different operating conditions. These kinds of difficulties cause modeling inaccuracies of AUV´s dynamics. Therefore, DFSM C is proposed for regulating heading angle in horizontal plane in presence of parametric uncertainty and disturbances. In this approach, two fuzzy approximators are employed in such a way that, to vary the supports of input-output fuzzy membership functions in the inference engine module. These fuzzy approximators are mainly utilized for updating width of boundary layer and hitting gain. Simulation results shows that, the reaching time and tracking error in the approaching phase can be significantly reduced with chattering problem can also be eliminated. The effectiveness of proposed control strategy and its advantages are indicated in comparison with conventional sliding mode control and fuzzy sliding mode control.