Design And Analysis On A 4-stewart Parallel Mechanism Motion Platform

Parallel motion simulator is an interdisciplinary recently developed and valued this years,which contains the latest research production and knowledge of multi-discipline such as mechanism,mechanical design,engineering mechanics,computer engineering science etc.With the development of science and technology parallel motion simulator has been more widely applied in most fields.In addition,along with the needs of the development of science and technology,the innovation of parallel motion platform design is put forward higher request.So it is greatly significant to research and develop parallel motion platform.In this paper,a kind of 4-Stewart parallel motion platform is designed to realize the multi-degree-of-freedom motion platform with better dynamic performance and high load/weight ratio.It has the advantages of smaller volume,better processing technology,simple manufacturing process,easier assembly and easy to control etc.It can be used as a vehicle simulator,flight simulator,equipment simulator,multi-functional operating table,balance rehabilitation training station and other types of carrying capacity as the main performance indicators of the dynamic platform of the mechanical body.In order to facilitate the analysis,mainly taking the 4-Stewart parallel platform,which applied to a new kind of vehicle driving training device,as the research object.Then its kinematics(including forward and inverse kinematics),bearing capacity and workspace were detailed analyzed and simulated.Firstly,multiple coordinate system of the vehicle driving training device is established.The position and posture of the vehicle under various road conditions and the conditions of the Stewart platform is analyzed.Compared with the traditional driving simulator the new vehicle driving device can achieve more of the car posture,and can be more realistic to simulate the car when the motion state.The kinematics inverse equation of the vehicle driving training device was accomplished by the method of the space vector relationship and verified through specific examples in MATLAB.It can be seen that the range of the branched motion is large.And when the end of the platform is given,the input of 24 active branched chains will be got.So the corresponding position inverse solution can be obtained by the position and pose description of the multi-road conditions.In addition,the Jacobi matrix iterative methodis used to solve the problem of positive solution of position,and the simulation is verified in MATLAB.Secondly,the force balance analysis of the whole device and any small Stewart motion platform is carried out.And the force screw of each movement platform is analyzed.On the basis of the force screw equation,the analysis of the singularity force Jacobean matrix discrimination and the bearing capacity are carried out.Then the space map of the bearing capacity is drawn in MATLAB.It is concluded that there is a higher load / weight ratio than the traditional driving simulator.Finally,based on the mathematical model and constraint equation of the driving training device,the working space boundary point search method is used to search the working space of the mechanism.And the three-dimensional map of the position and working space of the driving device is drawn in matlab to facilitate the optimization of the platform size.