Research On Control Method Of Underwater Vehicle Based On Fuzzy Sliding Mode

Autonomous Underwater Vehicle(AUV)is an unmanned submersible that can move or work autonomously.It is also known as an unmanned marine vehicle.It can perform specific tasks such as underwater geological survey,marine biological information collection,underwater military operations,and marine resource development.It can help humans accomplish tasks that humans cannot directly participate in.The application prospects of the device are very broad,and it also represents the future development direction of underwater vehicle technology.In order to improve the stability and robustness of the AUV control system,the sliding mode variable structure control and line of sight guidance(LOS),and their motion control in autonomous underwater vehicles The application in the design of the device was studied.First,mathematical modeling of AUV,establishing a mathematical model of AUV,including its mathematical model of kinematics and dynamics,and decoupling autonomous underwater vehicles with six-degree-of-freedom motion into vertical motion control models and horizontal motion Control model.Secondly,the AUV guidance system is studied.The LOS method is adopted as the navigation algorithm in the AUV path tracking process.The AUV will have water flow interference during the path tracking process,which makes the heading angle of the aircraft deviate from the desired sailing angle.Therefore,the slip angle is introduced to correct the navigation trajectory error appearing in the path tracking.At the same time,the simulation experiment is carried out to verify the AUV guide.The effectiveness of the system navigation algorithm.Thirdly,the design of the sliding mode controller for the vertical surface motion of the autonomous underwater vehicle is controlled.At the same time,the fuzzy control output is used to replace the switching characteristics of the sliding mode control.The fuzzy mode controller based on the exponential approach law also considers the different uncertainties of the hydrodynamic parameters.Finally,the simulation experiment is carried out to verify that the two fuzzy sliding mode controllers are designed.The response effect and good robustness,that is,the control system has better attitude control capability.Next,the sliding mode controller for autonomous underwater vehicle horizontal path tracking is designed.The AUV horizontal dynamic equation is established considering the disturbance of water flow.At the same time,the AUV horizontal path tracking error equation is established based on LOS method.Based on the decoupling method The control theory decouples the path tracking control system on the AUV horizontal surface into: speed control,position control and steering angle control system,and designs the sliding mode control law separately,and adopts fuzzy control output instead of sliding mode.The switching characteristics were finally simulated.The curve path and the straight path tracking were studied respectively,which verified that the controller has better path tracking effect.Finally,the design of adaptive sliding mode controller is carried out.Under the premise of stability theory,the reason of the chattering of the control system is analyzed,and then the corresponding parameters are selected to design the adaptive sliding mode control law,so that the system becomes more stable;also consider the case of input limitation,introduce a compensation mechanism,and propose a saturation error compensation algorithm.Finally,the simulation experiment is carried out.The curve path and linear path tracking research are carried out under steady flow and model perturbation respectively,which verifies that the controller has better path tracking effect and effectiveness.