Tracking Control of Unmanned Surface Vessels with Nonlinear Sliding Mode Method in Presence of Fixed & Moving Obstacles

In this paper, tracking control of unmanned surface vessels by using the robust mode sliding control in the presence of fixed and moving obstacles are investigated. The mathematical model of vessels is in three degree of freedom (3DOF) and only contains the kinematics and dynamics of relevant to surge, sway and yaw. These vessels are controlled in under actuated manner; although they have (3DOF), but only are equipped to two actuators in direction of surge and yaw. Next, we are used the mode sliding control method and introduced the first and second order of sliding surfaces as a function of tracking errors in direction of surge and yaw. Based on Lyapunov stability method, stability of dynamics of error has been proven. Then, we have put the fixed and moving obstacles in the trajectory of vessels to examine the safe crossing ability of them. Finally, numerical simulations are implemented to demonstrate the validity of proposed controllers.