Research On Motion Attitude Control Technology Of Underwater Vehicle

Because of the continuous scarcity of land resources,people began to research and develop the ocean.Therefore,underwater vehicle has become one of the important means to develop marine resources.It can replace people in the ocean to complete some difficult underwater exploration and underwater operations and other tasks.Therefore,the underwater vehicle technology is used in many fields.The motion attitude control technology is the core in the research of underwater vehicle technology,so this paper studies the motion attitude control technology of underwater vehicle.First of all,according to the function requirement and performance index,this paper proposes the overall motion control scheme of underwater vehicle,and introduces in detail how the underwater robot can complete the motion control in water.Due to the limitation of the experimental conditions,the underwater robot cannot be tested underwater,the 3D modeling of simulated motion control platform structure is completed by using SolidWorks,and the attitude sensor and thruster of underwater vehicle are debugged successfully.Secondly,in this paper,the motion space coordinate system and six degrees of freedom space motion model of underwater vehicle are established.Based on the stress analysis of underwater vehicle in detail,the motion of underwater robot with 6 DOF is decoupled into vertical plane and horizontal plane motion.Then,the plane motions are mathematically expressed by using kinematics equation,based on which the motion equations and transfer functions of bow angle,inclination angle and depth are derived and obtained respectively.Furthermore,the open-loop simulation is carried out.Then,this paper introduces the PID control system in detail,uses the PID controlalgorithm to control the motion attitude of the underwater vehicle.The PID controller is designed by using the simulink module of MATLAB software,and the closed loop simulation of the inclination angle,yaw angle and depth are carried out respectively.From their unit step response curves,it is obvious that the traditional PID control can be used to control the motion of the control object.However,there are some problems such as overshoot and system instability.Finally,this paper combines the traditional PID control with fuzzy control to form a new fuzzy PID control,which has the advantages of both fuzzy control and PID control.The fuzzy PID controller is designed by using MATLAB tool.The closed loop simulation of yaw angle and depth is carried out respectively.From their unit step response curves,it is obvious that the fuzzy PID control has the advantages of faster response speed,smaller overshoot and stronger stability than classic PID control and can achieve the requirement of design indices.Therefore,the improved fuzzy PID control is more suitable for the motion attitude control of underwater vehicle.