Design And Analysis Of The Lifting System For The Beam-type Lifting Arm Of A Catamaran

The increase in exploration activities in the marine field and the increase in offshore platforms have led to an increase in the installation and dismantling of offshore platforms.Currently,the installation and dismantling of offshore platforms are mainly completed by crane vessels.After decades of development,offshore platforms have gradually become larger,and the requirements for the lifting capacity of crane vessels have gradually increased.At the same time,in harsh marine environments,Ships and platforms may experience heave motion under wave excitation,which may have adverse effects on offshore operations.To ensure the accuracy,safety,and efficiency of operations,it is necessary to use heave compensation systems to complete auxiliary operations and enhance the safety and reliability of offshore operations.This paper proposes a design scheme for the heave compensation system based on a composite oil cylinder for the beam type boom of a large catamaran,confirms the design scheme of the hydraulic system,draws a schematic diagram of the hydraulic system,designs and calculates the main structural parameters and hydraulic system parameters of the lifting system,and establishes a three-dimensional model of the lifting system using SoildWorks.The stress of the lifting system during operation is analyzed,and then the key components of the lifting system are analyzed using AnsysWorkbench software for static,modal,and harmonic response.The static and dynamic characteristics of the structure are analyzed comprehensively,and it is concluded that the structure meets the requirements of static stiffness,strength,and dynamic stiffness,and has sufficient safety margin,further verifying the correctness and safety of the design.For the passive heave compensation system designed in this article,the working principle of the passive compensation system was explained,a dynamic model of the passive compensation system was established,and a set of data was designed for simulation research and parameter optimization under level 5 sea conditions.The effects of accumulator volume,pipeline diameter,pipeline length,and the period of mother ship movement on the compensation effect of the passive compensation system were discussed,and the shortcomings of the passive compensation system were analyzed.The limitations of passive compensation systems were pointed out,and in order to meet high-precision compensation needs,active compensation systems need to be introduced.A mathematical model is established for the active passive composite heave compensation system designed in this article.Based on this mathematical model,PID and fuzzy controllers are designed respectively.Simulation shows that when the heave compensation amplitude is greater than 2.5m,the control effect of PID control and fuzzy control is not expected.Subsequently,the displacement tracking control of the heave compensator was used as the outer loop of the controller,and the pressure control was used as the inner control loop.A fast terminal sliding surface was designed,and the virtual pressure control input values of the system was designed based on the backstepping method.The stability of the algorithm was verified based on Lyapunov stability theory,and the control accuracy and effectiveness of the system were verified through simulation.