Research On Dynamic Control Allocation And Fault Diagnosis Method Of X-rudder AUV

With the continuous exploration of the marine world,the Autonomous Underwater Vehicle has gradually become the focus of researchers.At present,most AUVs use a cross rudder layout.However,the AUV with the cross rudder layout has shortcomings such as low reliability,so the X rudder layout is gradually being used by researchers in new types of underwater robots.The X rudder AUV rudder control is an overdrive system,so it is necessary to increase the control distribution link to realize the rudder angle distribution;at the same time,multiple actuators also make the X rudder AUV rudder fault diagnosis more complicated.As a redundant system,when part of the actuator fails,the normal operation of the AUV can still be guaranteed after fault-tolerant processing.This article mainly researches on X rudder AUV control distribution,virtual control command dynamic adjustment,fault diagnosis and fault tolerance processing.The main research contents are as follows:(1)X-rudder AUV dynamics and kinematics modeling and controller design.Firstly,the current development status of X-rudder underwater device is introduced;the coordinates of the X-rudder AUV’s motion system are established and the relevant parameters required for the Xrudder AUV motion simulation are given,and the kinematics and dynamics equations corresponding to the X-rudder AUV are established.Establish the equivalent relationship between X-rudder and cross rudder;use traditional PID control methods to construct heel,trim,heading and depth controllers;prove the robustness and effectiveness of the designed controller through simulation.(2)Research on the improvement of X-rudder control distribution algorithm and dynamic adjustment method.First,the X-rudder AUV control distribution model is established.For the X-rudder AUV control distribution,the pseudo-inverse method is used without considering the constraints of the actuator and can only solve the single-objective optimization problem.An improved fixed point control distribution algorithm is proposed.On the premise of ensuring the calculation accuracy of the fixed point algorithm,the calculation efficiency of the algorithm is further improved.Aiming at the problem that the virtual control command is not in the reachable set super box,a dynamic adjustment algorithm based on zero space is proposed.For virtual control commands not located in the super box,a dynamic adjustment link is added between the control law and the control distribution link;the zero-space vector is used to dynamically adjust the rudder angle that exceeds the constraint,so that the actual output torque generated is as close as possible to the expectation Torque: The dynamically adjusted virtual control instructions are passed into the control distribution algorithm for solution,and the effectiveness of the algorithm is proved by simulation.(3)Research on X-rudder AUV fault diagnosis and fault-tolerant processing methods.First,analyze the failure of the X-rudder and use the sliding mode state observer to obtain the residual difference between the ideal motion state of the AUV and the actual state obtained by the dynamic model as sample data.For the fault judgment,the linear SVM model is used to judge;for the fault location,because it is a multi-classification problem,a 1V1 one-to-one SVM model and a 1Vn SVM model are constructed for fault location,and finally a 1V1 SVM model is selected.Different fault-tolerant processing methods are proposed for different rudder failures.Since the X-rudder control is a redundant system,there is no need to redesign the entire control system when a failure occurs,only the X-rudder control efficiency matrix and virtual control commands need to be reconstructed.According to different fault conditions,different working conditions are set;the effectiveness of the designed fault-tolerant processing method is proved through simulation.