Trajectory Tracking And Formation Control For Underactuated Surface Vessel With Constraints

In recent years,with the development of marine resources,the motion control of underactuated surface vessel has gradually become a research hotspot.Since the vessel often perform tasks in some complex areas,such as densely populated reefs and undercurrents,one or several states of it needs to be constrained.How to deal with the constraint problem of the underactuated surface vessel has a very important research value.Besides,in the process of performing tasks,the vessel will encounter interference such as wind,wave and current,as well as the requirements on the control time.Therefore,the robustness and timeliness of the underactuated surface vessel have also become a hot issue in research.In this paper,we are aiming at the motion control system of the underactuated surface vessel,considering its state and output constraints,the problem of trajectory tracking and formation control of the underactuated surface vessel is studied by combining the backstepping method,barrier Lyapunov function method,finite-time and prescribed-time control theory,etc.the research contents are as follows:Firstly,the problem of trajectory tracking control for underactuated surface vessel with full state constraints is studied.According to the underactuated structure of the vessel,the system is transformed into two subsystems,and the constraint conditions were correspondingly transformed.A finite-time disturbance observer is designed to estimate the disturbance to the surface vessel.Then a tan-type barrier Lyapunov function is constructed to ensure that the error system does not violate the constrained conditions and the corresponding controller input is designed to ensure the errors can converge to zero.Simulation results show the effectiveness of the design method.Secondly,the problem of finite-time cooperative path following for underactuated surface vessels with surge velocity and yaw angle constraints is studied.The integral line of sight guidance law and the finite-time disturbance observer are introduced to deal with the matching and mismatching disturbances of the surface vessels.Asymmetric barrier Lyapunov functions are designed to ensure that the surge velocity and yaw angle do not violate the constraints.Then,the controller input is designed by combining with the finite-time control theory,so that the surge velocity and yaw angle tracking errors can converge to zeros in the finite-time.Simulation results show the effectiveness of the controller.Finally,the prescribed-time formation control is studied for underactuated surface vessels with asymmetric constraints on line of sight range and bearing angle errors.Based on the line of sight guidance law,the USV model is transformed into a leader-follower formation control model,and then a novel prescribed-time disturbance observer is designed to estimate the environmental disturbances.Asymmetric barrier Lyapunov functions are constructed to ensure the line of sight range and bearing angle errors do not exceed its contraints.Combined with the barrier Lyapunov function,backstepping technique and prescribed-time control theory,the corresponding controller is designed to enable the system to complete the formation task in the prescribed time.The simulation results show the effectiveness of the designed controller.