Research On Path Planning And Tracking Control Of Underwater Snake-like Robot With Orthogonal Joints And Side Vector Thrusters

In recent years,with the progress of science and technology and the development of society,the development and utilization of marine resources has attracted wide attention from all over the world.The underwater snake-like robot can work in a complex underwater environment.Its emergence has brought great convenience to underwater work such as marine resource exploration and offshore platform maintenance.However,the traditional underwater snake-like robot moves by meandering,which requires a large forming space,so it is not suitable for moving in a narrow space.Therefore,it is necessary to design an underwater snake-like robot which is suitable for moving in a narrow space.In addition,the current underwater path planning algorithm rarely considers the consumption caused by turning on the path,and most of them are for AUV.Since the AUV has only one link and the underwater snakelike robot is composed of multiple links,the difference in structure between the two will lead to different energy consumption when turning.Therefore,it is necessary to propose a path planning method that considers the energy consumption on the path and is suitable for the underwater snake-like robot.At the same time,due to the strong coupling between the movement of the overall centroid of the underwater snake-like robot and the movement of each link,it is difficult to accurately control each link.Therefore,it is necessary to propose a new control strategy for path tracking control.In view of the above situation,this paper has done the following research:(1)Aiming at the shortcomings of the current underwater snake-like robot,an underwater snake-like robot with orthogonal joints and side vector thrusters is designed.According to the structural characteristics of the designed underwater snake-like robot,its three-dimensional dynamic model is established by using D-H coordinate method,Newton-Euler method and Morrison equation.(2)Aiming at the shortcomings of the ant colony algorithm in the current path planning algorithm,such as slow convergence speed and easy to fall into local optimum,and according to the characteristics of the maximum angle limit of the designed underwater snake-like robot when turning,and the relationship between its energy consumption and the angle on the path,an angle-based adaptive ant colony algorithm is proposed to plan its path.The simulation results show that the proposed algorithm overcomes the shortcomings of slow convergence speed and easy to fall into local optimum of ant colony algorithm,and can find a path with short length,small cumulative rotation angle and suitable for underwater snake-like robot.(3)Aiming at the problem that the current path tracking control strategy of underwater snake-like robot only controls the overall centroid path without considering the path of each link,a motion decoupling control strategy between links is proposed,so that each link of underwater snake-like robot can track the desired path.According to the established kinematics and dynamics model,a sliding mode control method based on LMI nonlinear disturbance observer is used to track the designed underwater snakelike robot.The final simulation results show that the proposed control strategy and control method can make each link of the underwater snake-like robot track the desired path.(4)According to the structure of the designed snake-like robot,an underwater snake-like robot prototype was manufactured by selecting appropriate materials and components,and the corresponding control program was written.The path tracking control experiment in two-dimensional plane is carried out by using the proposed control strategy and control method,and the correctness of the simulation results is verified.