Research And Design Of Wave Compensation Control System Based On Stewart Parallel Mechanis

With global climate change,countries are actively developing marine wind power resources.The offshore wind power operation and maintenance vessel will move with six degrees of freedom under the influence of waves,which poses a safety hazard to the operation and maintenance personnel who transfer to the tower base of the wind turbine.The ship-borne wave compensation platform can isolate the wave disturbance to a certain extent and ensure the safety of operation and maintenance personnel.Therefore,this paper takes the Stewart parallel robot as the prototype to study the dynamic modeling,dynamic parameter identification,ship heave motion calculation,and wave compensation control strategy of the wave compensation platform.The research contents and results of this paper are as follows:Firstly,the kinematics model of the Stewart parallel robot is analyzed,and a dynamic modeling method considering the kinematics of the base platform is proposed.The dynamic analysis is simplified by the Kane equation,and its dynamic equation in the non-inertial environment is established.Then model the driving joint electric cylinder of the robot.The visual simulation model of the Stewart parallel robot is established using MATLAB/Simulink,and the correctness of the kinematic model and dynamic model is verified.Then,aiming at the problem of inaccurate parameters of the dynamic model,the identification of the dynamic parameters is carried out.The parameters of the dynamic equation are separated according to a set of minimum inertia parameters,and the observation matrix to be identified is obtained,and the design and optimization of the excitation trajectory are transformed into a constrained nonlinear optimization problem.To improve the identification accuracy,the particle swarm algorithm is used to identify the dynamic parameters.Simulation analysis verifies the validity of the identification algorithm.Next,the key heave motion calculation in ship disturbance pose detection technology is studied.A heave filter is used to filter the noise and low-frequency interference in the acceleration information,and an improved heave filter is proposed to compensate for the phase error.Aiming at the high-dimensional nonlinear problem of the heave motion model,a heave motion estimation method based on a volumetric Kalman filter is proposed.The solution accuracy of the two algorithms is verified by simulation and experiment.After that,the three closed-loop control of the electric cylinder is used to control the position of the joint space of the wave compensation platform.Aiming at the cumbersome problem of setting the parameters of the position loop,a fitness function is designed and the parameters are self-tuning based on the genetic algorithm.In order to enhance the highfrequency signal position tracking and anti-disturbance capability of the electric cylinder,a compound feedforward control strategy combining velocity feedforward and dynamics feedforward is adopted.The simulation results show that the composite feedforward controller can effectively improve the control performance of the wave compensation platform.Finally,based on the experimental platform of the ship wave compensation system based on the Stewart motion platform,the upper computer software of the wave compensation system is designed and developed,and the function of the experimental platform of the wave compensation system is perfected.The heave motion solution and disturbance compensation performance of the wave compensation platform control system are tested by experiments.