Research Of Ship Six Degrees Of Freedom Motion Simulation Platform And Its Control Method

Along with the development of technology of shipbuilding industry, in order to solve the key technical problem of ship and its relative equipment development, it is necessary to research the physical simulation system. Owing to the characteristics of big rigidity, high precision and high load deadweight ratio, the parallel mechanism has broad application in the fields of robot, motion simulator and numerical control machine, etc. Therefore, this dissertation researched the ship 6-DOF motion simulation platform which has a parallel structure, and made deeply research on some key technology problems and the control method.Firstly some relative kinematical concepts were introduced. Aiming at the defect of numerical value iterative algorithm that the precision and convergence depend on the initial value when calculating the solution of forward kinematics, an improved PSO algorithm and Newton-Raphson numerical value algorithm were combined here, thus an effective method to calculate the solution of forward kinematics was proposed. This method solved the difficulty of choosing the initial value for the numerical value algorithm, and obtained higher precision. It also has a better universal property.Optimal design of the mechanical structure is important to the kinematical and dynamical performance of parallel mechanism, so it took average dexterity as the object function, established the structural optimizing design model with all kinds of restrictions. At the same time, by improving the global searching, local searching and pheromone update rule effetely, it obtained the improved ant colony algorithm which is more suitable to solve the continuous optimization problem. And this improved algorithm was applied to the optimizing problem of parallel platform. Through contrasting and analyzing, the validity of this algorithm was approved. This improved ant algorithm provided valuable reference for solving continuous optimization problems such as the structural design of parallel mechanism.Start with analyzing branched chain of the simulation platform, it established the relationship of structural parameter error and output pose error, then obtained the error model established from the solutions of forward kinematics which included all forty-two structure parameter errors. The simulation results show that this error model can calculate output pose errors of parallel manipulator directly with the given structure parameter errors. And the theory of pose accuracy of ship 6-DOF motion simulation platform was analyzed, and the reasonable random sample models of structure parameter error were established. By using Monte Carlo method the statistic characteristic of pose errors was simulated and analyzed.This dissertation established mathematic model of single channel hydraulic position system of ship 6-DOF motion simulation platform. And it analyzed the pressure and track characteristics when the symmetry valve controlled asymmetric cylinder power mechanics were in the state of forward and backward movement.A hybrid control strategy for ship 6-DOF motion simulation platform was proposed in this dissertation, in which synchronized control was implemented by using CMAC, and the joint space controller based on Fuzzy-PID switch and feed forward of load pressure disturbance was designed for the single channel hydraulic system. The results of simulations and experiments show that with this hybrid control strategy, the influences of asymmetric characteristic, varied load and disturbance force, etc. are eliminated, and the movement synchronized characteristics for multi-actuator are improved. So it made the ship 6-DOF motion simulation platform obtain perfect movement performance and tracking precision.After designing total system of ship 6-DOF motion simulation platform and its computer control system, the experimental research and results analysis of the proposed hybrid control strategy were carried out. The results show that the control strategy is feasible and the development of ship 6-DOF motion simulation platform is successful.