Research On Modeling And Control Strategy Of Parallel Six-degree-of-freedom Motion Platform

The parallel six-degree-of-freedom(6-DOF)motion platform is used as a smart ship motion simulator in a large stage performance scene,resulting in a swinging action that makes the stage effect more vivid and real.At present,most researches on parallel 6-DOF motion platform simplify the series-parallel branch directly into drive rod,neglecting the influence of other parts of series-connected chain on the motion of the upper platform,resulting in the errors on the actual platform are larger.In this dissertation,a parallel 6-DOF motion platform that is applied in the intelligent ship motion simulation is analyzed,based on the analysis of the effect of the series-parallel branches on the pose of the upper platform,a mathematical model of kinematic inverse and a simulation model of motion platform are established,it provides a theoretical basis for pose analysis and motion control of a real parallel 6-DOF motion platform.Firstly,the upper platform,the lower platform and the coordinate system of each branch are established by D-H representation.The homogeneous coordinate transformation matrix is introduced to analyze the mapping relation between the adjacent joint coordinate systems.In the simulation environment of Simulink,the solution model of the solving equation is deduced.The correctness of the mathematical model of the inverse pose of the upper platform is validated by comparing with the mechanical parameters of the actual parallel 6-DOF motion platform.Then,according to the mechanical structure and specific parameters of the actual parallel 6-DOF motion platform,a three-dimensional physical model of the parallel 6-DOF motion t platform is established by using a Matlab/SimMechanics toolbox.Finally,a platform simulation system based on fuzzy PID controller is built.Through the experiments of single degree of freedom on the platform and the combined motion experiments of horizontal,yaw,circle,yaw and circle of multi-degree of freedom combination,the established inverse kinematics model,solution module and fuzzy PID control module and the three-dimensional physical model of the platform are correctness and applicability.To sum up,this dissertation established mathematical model,three-dimensional physical model and fuzzy PID control simulation model of inverse kinematics of the upper platform in parallel 6-DOF motion platform used in the smart ship motion simulator.By comparing with the actual 6-DOF motion platform proves the correctness of the pose and inverse kinematics equations and the rationality of the three-dimensional physical model.The work done in this dissertation has important guiding significance for the pose analysis and optimal control of the parallel six-freedom Motion platform which is actually used in the intelligent ship motion simulation.