Detection And Control Of The Offshore Boarding Bridge Pitch Circuit And Telescopic Circuit

The boarding system of offshore wind power operation and maintenance ship is a large-scale control system which can transport persons and equipment of operation and maintenance.It is mainly used for the maintenance of wind turbines in offshore wind power plants.Nowadays,the development of offshore wind power promotes the need of wind power equipments with the operation and maintenance function,and offshore wind power construction will be constructed in the offshore where far away from the coast.This can not simply rely on this traditional way to repair the wind power platform,a reliable and strong anti different sea conditions landing system has been attached great importance to by the country and enterprises.The system studied in this paper is a subsystem applied to the boarding system of the offshore wind power operation and maintenance ship.Because the3-DOF boarding footbridge and the 6-DOF parallel platform can be seperated in kinematics,this paper will study the boarding footbridge of wind power system.This paper focuses on the pitch loop's and the telescopic loop's detection and control of the 3-DOF footbridge in the boarding system of offshore wind power and wind power operation and maintenance ships.Based on the model dynamics analysis,the synchronization of the two cylinders in the pitch motion of the boarding footbridge and the expected speed and position control of the telescopic loop are solved.Firstly,this paper introducesthe structure and motion realization of the offshore wind power landing footbridge and designs the computer control struckt.According to the structural parameters of the system,the forward kinematics equation of the landing footbridge is deduced with D-H parameter method.The posture matrix and the workspace of the landing footbridge are obtained.It can be as the reference of the whole system design.Based on Newton-Euler equation,the rotation torque of pitching loop motion and the pull force of sliding ladder motion are derived.The executive element of pitching loop are two asymmetrical hydraulic cylinder.In the valve-controlled asymmetric hydraulic cylinder system,there are some differences between the transfer functions in the contraction and extension directions,and use the weighted average method linearizing the transfer function.According to kinematics and dynamics,thetorque function with pitch angle as independent variable is transformed into the form related to the displacement of hydraulic cylinder,and the equivalent load and other parameters are calculated.Through the mathematical modeling of this part,it can be seen that the system belongs to time-variable and disturbance system,because of the mass center transferring of bridge ladder caused by the length of bridge ladder.To solve this problem,a synchronization control algorithm based on fuzzy adaptive PID is proposed to achieve the synchronization control of valve-controlled asymmetric hydraulic cylinder.Three control parameters of PID are modified online by synchronization error and its differential.Then,fuzzy adaptive PID is verified by simulationin the synchronous tracking errorwith time-varying disturbance and bias force system.Finally,the effectiveness of the controller is proved by experiments.The valve-controlled hydraulic motor completes the telescopic motion of the offshore wind power landing bridge,and the paper establishes the transfer function of the system based on the dynamic model.When the pitch angle of the footbridge is different,the time-varying disturbance term is brought by the change of the friction force and gravity component.Therefore,a sliding mode variable structure controller based on disturbance observer is proposed to control the speed and position servo motion of the sliding ladder.Firstly,the disturbance in the system are calculated equivalently.Based on Lyapunov stability theory,the disturbance observer is designed,and according to the measurability of the actual signal the disturbance observer is improved.This paper designed the speed sliding mode control and position sliding mode control based on perturbation observer.The stability of the sliding mode control based on the disturbance observer and the sliding mode servo controller based on the disturbance observer is proved by using Lyapunov stability principle.Finally,simulation and experiment verify the correctness of the designed controller in the speed control and position servo control of the moving ladder.In this paper,a ladder end assembly is designed to detect the information of the lap between the ladder and lap platform.During the test,it consists the lap preture closed control in the pitching loop and telescopic loop.