Model-Free High Order Sliding Controller for Underwater Vehicle with Transient Process

Underwater environment is highly dynamic,presenting significant disturbances to the vehicle in the form of underwater currents.Additionally,the main difficulties associated with underwater control are the parametric uncertainties. The model-based controller need precise hydrodynamic coeffcients or the model of ROV,but in practice it is very hard or impossible.In order to avoid this problem,a model-free high order sliding mode controller is proposed,and design a reasonable transient process which make the controller have a good performance for any initial error condition.Performance of the proposed controller is verified using numerical simulations,implemented in a four freedom nonlinear underwater vehicle model. Simulation results show that exponential fast convergence of position and attitude,overshooting is very small,for any initial condition.And the controller is proposed needs few parameters to adjust. Algorithm is very easy to complie,could meet the engineering needs.