Research On Error Modeling And Compensation Methods Of Cable-driven Mechanism For Wave Motion Compensation

In long-distance marine operations,the transfer of materials at sea and replenishment on the way are important means for logistical support,and wave motion compensation system is the key to ensure its smooth progress.Due to the ever-changing marine environment and unpredictable real-time sea conditions,the requirements for marine replenishment are becoming more and more stringent.Wave motion compensation technology has become an important factor restricting the development of offshore hoisting.In order to satisfy the operational needs of accurate loading and unloading for materials in concurrent replenishment,and realize the vision of all-weather operations at sea as soon as possible,this paper designs a rigid-flexible cable-driven wave motion compensation system with six-degree-of-freedom,and conducts motion performance,error modeling and error compensation for it.So that can reduce even eliminate the interference caused by waves in multi-dimensional directions during hoisting operations,and ensure the safety,accuracy,stability and efficiency in the course of work.Aiming at operation requirements of side-by-side replenishment,this paper innovatively designs the structure of cable-driven wave motion compensation system.According to structural characteristics and application scenarios of wave motion compensation system,the spatial layout of cable points is firstly arranged reasonably,then the kinematic inverse solution is solved by using space closed-loop vector method,and then the dynamic model is established by using Newton-Euler equation,finally verified the correctness of kinematics and dynamics models via Matlab and Adams software co-simulation.Aiming at the problem of output accuracy in wave motion compensation task,the error sources of wave motion compensation system are analyzed from multiple entry points,and the influence of component in cable-driven system(the pulley)on output accuracy of cable length is studied.Based on matrix differential method,the system error model is established firstly,then the nonlinear equations covering each error parameter are derived,and then the parameter error is quantitatively analyzed.The simulation results show that the length error parameter of cable branch chain is a key factor affecting the pose accuracy of operation platform.In order to improve the output accuracy of wave motion compensation system,the particle swarm optimization algorithm with improved inertia weight is used to optimize the multiobjective optimization function including error parameters,which verifies the superiority of improved algorithm and its effectiveness role in the optimization of system comprehensive error parameters.The irregular cable length output is predicted nonlinearly through long-short term memory recursive neural network.Compared with theoretical value,the average value of predicted cable length error is reduced by 84.97%,which reduces the retraction error of cable branch chain and improves the motion accuracy of wave motion compensation mechanism.