Research On Motion Control Of X Rudder Autonomous Underwater Vehicle

With the increasing demand for marine resources and the goal of accelerating t he construction of a maritime power proposed by the 19 th National Congress of the Communist Party of C hina,people gradually attach importance to the research of Autonomous Underwater Vehicle(AUV)technology.Compared with the traditional layout of cross rudder,the layout of the X-type stern rudder has the characteristics of high rudder efficiency,good maneuverability and rudder redundancy,so it is having more and more applications to the development of AUV.Therefore,the research on the motion control of X rudder AUV has engineering application value.This paper analyzes the difficulties in the motion control of the X rudder AUV,and focuses on the trajectory tracking control of the X rudder AUV and the four rudder control distribution problems.Firstly,because the steering response of the X rudder AUV is difficult to be as intuitive as that of cross rudder AUV.In order to obtain the steering motion response law of X rudder AUV,a reasonable simulation experiment was designed to compare the motion generated by the X rudder AUV different rudder operation and summarize the steering response law based on the AUV model established.In addition,in order to compare the steering response of the X rudder AUV and the cross rudder AUV,a simulation experiment under the same conditions was performed on the cross rudder AUV of the same size,and the simulation results were compared and analyzed with the X rudder AUV.Secondly under the condition of time-varying external interference and the system model’s inaccurate determination,the trajectory tracking control method of the X rudder AUV was studied,and a sliding mode control method based on dynamic sliding mode surface was proposed The method has the characteristics of simple structure and easy parameter adjustment.On this basis a new type of fast smooth reaching law is designed to reduce the chattering of sliding mode control methods.Lyapunov stability theory is used to prove that the proposed control method can converge stably,and the effectiveness of the proposed sliding mode control method and chattering reduction method is verified by simulation experiments.Finally,an accelerated fixed point iteration method is proposed to solve the unique four rudder control allocation problem of X rudder AUV.This method can solve the problem that the pseudo inverse method can not consider the physical constraints of rudder Secondly,the pseudo inverse method can only give a set of unique solutions,and can not adjust the different values of solutions according to the requirements of the task.In addition,the accelerated fixed point iterative method can reduce the amount of iterative calculation,improve the speed of iterative calculation and enhance the real-time performance of the system on the premise of ensuring the control accuracy.Finally,the control effects of the three control allocation methods are compared through simulation experiments and the effectiveness and the superior performance of the accelerated fixed point iterative method is verified.