Swing Trajectory Control Of Ship Motion Simulation Mechanism Driven By Electrohydraulic

The ship simulator has been widely used in the development of ship equipment and the training of ship personnel,for its safety,economy and efficiency.The ship motion simulation mechanism,as an important part of ship simulator,is responsible for realizing the reality of equipment motion.Most of the technical research on the ship motion simulator is built on the basis of regular swing of ship,while the actual swing of ship is irregular due to the random waves in the real marine environment.In this paper,the simulation trajectory generation,mathematical model establishment and controller design centered on the ship motion simulation mechanism were studied,with a view to realize the simulation of the irregular swing trajectory of the ship by controlling the ship motion simulation mechanism,make the simulated motion more realistic to further improve the simulating ability of the equipment for adapting various working conditions.Firstly,a proposal of 6-DOF random simulation trajectory of ship motion simulation mechanism was established in this paper.With the sea condition parameter,ship parameter and ship motion state as simulated conditions,this proposal established a dynamic equation for describing the swing of a ship according to the space dynamics theory of rigid body,and the formula of ship force-loading under irregular wave effect was introduced based on spectrum analysis theory.After equation solving with the assist of Runge-Kutta method,the swing trajectory of the ship was calculated and can be transformed into the simulated target trajectory of the mechanism.Secondly,simulated target trajectory of the mechanism was transformed into the target displacement trajectory of the valve-controlled cylinder to describe the input relation of the system by means of parallel mechanism inverse displacement analysis.The method of particle swarm optimization(PSO)and three-order Newton-Raphson iterative method were used to propose the positive numerical solution of the mechanism to describe the output relation of the system.The velocity analysis,acceleration analysis and dynamic analysis of the mechanism were gradually carried out and the dynamics equation of the mechanism was established based on the virtual work principle.According to this equation,the traditional load and force balance equation of valve-controlled cylinder were modified and the equivalent mass matrix of the equation,the equivalent viscous matrix and equivalent gravity disturbance were obtained by integrating six channels.Combined with the hydraulic cylinder flow continuity equation,the valve flow equation and the mathematical model of the electrical components,systemic state space expression model was established to completely describe the "input-state-output" process of the system.Thirdly,the control strategy of the system was analyzed from the controller structure,algorithm and setting method based on the characteristics of multi-input and multi-output in the system.In terms of parameter setting,the differential evolution algorithm with the system transient response index as fitness function based on model simulation was used to optimize the parameters.The performance of PI and FOPI was compared by simulation analysis to explain the influence of synchronization,and the fitness function of the differential evolution algorithm on the synchronization index based on peak time was modified.Lastly,with the modification of mathematical model based on the experimental data as well as the performance of parallel control structure FOPI and adjacent cross-coupling control structure FOPI based on the experimental analysis,considering the uncertainty of system,Fuzzy controller was added on the FOPI in order to further improve the adaptability of the system.The control performance of parallel FOPI,adjacent cross-coupling FOPI and adjacent cross-coupling Fuzzy-FOPI was verified through the 6-DOF swing experiment of the mechanism.