Research On Motion Control Of Underwater Drilling Robot

The ocean is rich in energy resources.The development of marine resources is the only way to solve the problem of population growth and resource depletion.The speed of China’s marine development continues to accelerate because of the marine powerful nation strategy.ROV has become an important tool in the maintenance of marine structures and underwater rescue due to its mobility and deep-water operation ability.It can take the place of divers to carry out the detection and maintenance in complex underwater environment,and at the same time,it can complete the resource exploration task in the ocean.Underwater drilling is a common operation method in the maintenance of marine structures and underwater rescue,and it can escort underwater structures and rescue.The flexibility of the ROV with the drilling tool allows drilling in the complex subsea environment.It can realize drilling operation at any working surface and angle,so it can complete underwater drilling more smoothly.In this paper,a special four-vector propulsion drilling ROV is designed for the underwater drilling operation.Based on this ROV,the establishment of kinematics model,mechanical analysis of underwater drilling process,controller design and thrust distribution of nonlinear system are studied.Main contents and achievements include the following aspects.First of all,according to the actual working conditions and movement requirements of underwater drilling operations,this paper proposes a drilling ROV based on four-vector propulsion.The six degrees of freedom motion of the ROV is achieved by vector placement and rotation of the propeller,and it can reduce the number of propellers and keep redundant thrust.This paper completed the structural design of ROV,including the vector arrangement of propellers,the connection between propeller and steering gear,the main structure design and material selection of ROV.The virtual prototype is designed and the ROV entity is assembled.Then,according to the stress conditions under water,this paper established the complete six-degree-of-freedom kinematics and dynamics model of the four-vector propulsion drilling ROV.In this paper,a model test of a drilling ROV with fourvector propulsion was carried out,it tests the correctness and maneuverability of the ROV model.Subsequently,this paper designs a discrete PID controller for the drilling ROV with four-vector propulsion,and achieves the expected goal by adjusting the control parameters.At the same time,this paper designs a nonlinear constrained thrust distribution strategy based on the combination of interior point method and NewtonRaphson method.This method solves the thrust distribution problem of four-vector propulsion drilling ROV based on the optimal energy consumption.Finally,this paper carries out the simulation of the ROV model of four-vector propulsion drilling.This paper analyzes the mechanical properties of drilling on concrete and metal surfaces,and it explores the relationship between the maximum torque and maximum thrust of the underwater drilling robot.Based on this relationship,it determines the range of drilling that can be performed by the ROV.In this paper,the hovering,posture movement and rotation of the four-vector propulsion drilling ROV and the drilling on the concrete and metal surface are simulated and tested.By observing the motion speed,posture changes and thrust distribution of the ROV,the maneuverability and stability of the four-vector propulsion drilling ROV were tested.