Modeling Analysis And Visual Control Of A Serial-Parallel Hybrid Gangway For Transferring Offshore Personnel

The ship will have six-dimensional motion under the influence of sea wind and waves,in which roll,pitch and yaw can be compensated by the ship’s dynamic positioning system,while roll,pitch and heave motion can not be compensated by the ship itself,when the staff transfer between the ship and the offshore wind power tower will bring safety risks,so it is necessary to design a stable transfer device that compensates for roll,pitch and heave.In order to meet the application requirements of miniaturization,low cost and high precision of transfer device,a kind of tandem hybrid bridge with visual guide docking is designed in this paper.And carry out the research on its mechanical structure,kinematics and dynamics,visual docking scheme and control strategy,the specific contents include:Firstly,a 3-R(4R)S/RPR parallel platform is proposed based on the law of ship rocking and the requirements of the subject.Then,a scheme of tandem and hybrid personnel transfer bridge is proposed.A variety of configurations of parallel mechanism and series mechanism are proposed and the concrete scheme of personnel transfer bridge is determined by comparison.Then the 3D simulation model is established with Solid Works software,and the torsional stiffness is analyzed with Ansys software.Secondly,the kinematic model of the 3-R(4R)S/RPR +RRP hybrid bridge is established,and its position,velocity and acceleration are analyzed.The kinematic model was programmed and calculated by MATLAB to obtain the motion curves of each drive.Then the simulation was carried out by Simulink.The correctness of the kinematic model was verified by comparing the simulation value with the calculated value.Then,the dynamic model of the personnel transfer bridge was established by using Newton-Euler method,and the correctness of the dynamic model was verified by Simulink simulation.Then,the visual guidance docking scheme between the transfer bridge and the offshore wind power tower is studied.A stable docking scheme based on binocular camera and deep learning is proposed to meet the docking requirements of transfer bridge and wind turbine tower.Then the improved YOLO neural network is used to realize the recognition and tracking of wind power tower,and the three-dimensional coordinate measurement of the wind power tower is completed by using binocular vision.Then,the real-time position and pose detection of the platform in parallel with the transfer bridge is realized by combining the camera and IMU with the visual inertia odometer(VIO).Finally,a wireless data transmission system is designed to transmit the parallel upper platform pose and wind turbine tower coordinate obtained by image processing to the transfer bridge control system.Finally,the hydrodynamic simulation of the ship is carried out to get its motion curve under the two and three levels of sea conditions.Then the PID control algorithm is used to design the control system of the transfer bridge and the control effect is verified by simulation.Finally,the visual guidance system is combined with the virtual prototype built by Simulink to carry out the stable docking experiment between the transfer bridge and the wind power tower.The stable docking effect under two-and three-order sea state disturbance is verified.