Control Methods Of Unmanned Surface Vehicle

The motion control technology of unmanned surface vehicles(USV)is of great importance for a USV to navigate safely and economically.The movement mathematical model of USV is the core of the study movement and control.In the theory and practice research of USV,the first thing to establish a mathematical model.Mathematical model of USV is to describe variables in the system equations of motion of the relation USV between the dynamic performances.Establishment of correct or not,relation to USV research results.Therefore,the establishment of mathematical model of USV is a priority for the USV movement and control.But Because of the nonlinearity,time varying aspects and uncertainties of USV steering,PID control algorithm is difficult to adapt the changing situation,the conventional adaptive control methods are also not effective enough because it's difficult to find the accurate mathematical models.Since fuzzy control is very suitable for those complicated control objects whose accurate models are unavailable,it's an important measure to apply fuzzy control to the case of USV motion control,promising to solve the problem mentioned above.Facing this trend,First mathematical modeling of USV is established,second movement control method is studied.The main contributions of the thesis are summarized as follows.Three degrees of freedom movement Abkowitz nonlinear unmanned surface vessel(USV)movement model is established,and then the nonlinear model is linearized.Unmanned surface vessel movement under the interference by wind,wave and flow have been taken into consideration.And then the USV motion control system based on Simulink simulation research and the simulation results is presented.The simulation results show that the established model consistent with the actual movement regularity of unmanned surface vessel,using this model can be very convenient for unmanned surface vessel research on the laws of the motion control.It is aimed to be beneficial for performance tests of USV maneuvering and studies for USV control strategies.Introduces the basic theory of fuzzy control,and analyses the general steps of the fuzzy logic control system discuss the structure composition of the fuzzy controller based on fuzzy reasoning in detail.Simulation about speed control of USV has been done with fuzzy controller,and results of the simulation experiments have been analyzed compared with classical PID controller.The principles of course keeping and tracking control are studied and the applications of fuzzy control theory to the USV course keeping control are investigated.According to the different characteristics of USV maneuvering in stages of course changing and course keeping,fuzzy controllers for course changing and course keeping are designed.For testing purpose,simulations with disturbances are carried out firstly where the Abkowitz nonlinear model is employed;the simulation results show that the designed control system reveals good dynamic performance,anti-disturbance ability and robustness.