Kinematucs Research Of Six Degrees Of Freedom Platform

The 6-DOF(Six Degrees of Freedom)platform plays an important role in national defense construction,including scientific research,automatic production,product testing,life entertainment and so on,so the research and development of 6-DOF platform is a very significant thing.In this paper,the kinematics theory,kinematics simulation of virtual prototype,motion error analysis and error compensation are studied respectively.The details are as follows:The mathematical model of kinematics inverse solution of platform with 6-DOF is established by Matrix transform method.Based on the conclusion of kinematic positive solution of parallel mechanism obtained by Huang Zhen of Yanshan University,the position position of the moving platform and the expansion error of the hydraulic cylinder are obtained.According to the displacement formula of hydraulic cylinder,the expression of velocity and acceleration of any hydraulic cylinder on the moving platform is derived.By using geometry method and analysis method respectively,the limit conditions of the length of the 6-DOF platform on the mechanism motion and the restriction conditions of the upper and lower spherical subangle on the mechanism motion are obtained.After modeling the six degrees of freedom platform with CAXA,the kinematics simulation experiment of virtual prototype was carried out in ADAMS.By comparing the curve of the displacement of the hydraulic cylinder with the results of kinematic regression,it is proved that kinematic regression is reasonable and feasible.A graph of the angular velocity,angular acceleration and displacement of a platform with six degrees of freedom is obtained.The expression formula between displacement error of hydraulic cylinder and position error of platform is derived by using matrix calculus.Based on the results of kinematic positive solution,the position error of the platform is obtained.The relationship between position error and expansion error of each hydraulic cylinder is analyzed.The position error difference of the platform with 6-DOF is calculated by MATLAB.The position error of the platform with 6-DOF is fitted by least square method.The error difference between the position of the hydraulic cylinder and the position of the platform is described in the plane coordinate system.The position error of motion platform is compensated.The reduction value of position error is obtained.