Motion And Dynamic Analysis Of A Multi-DOF Stable Platform

The parallel mechanism has the advantages of high stiffness,high accuracy,no error accumulation,strong bearing capacity and good dynamic characteristics^[1],plays a very important role in high-end equipment manufacturing,motion simulations,tracking and positioning.Stewart parallel platform is a very typical six degree of freedom parallel mechanisms.Since it has been proposed,having attracted a lot of scholars which both at home and abroad to continue studying.This paper focuses on the application of Stewart parallel mechanisms in the field of stable platform,mainly used to isolate the active disturbance produced from insides or outsides.Because of its own organization structure is relatively complex,the process of calculating the motions and dynamics are extremely complex,and the interference source in the experimental process is complicated to applied on and also the realization.These become the main limiting factors of the development and application of the stable paltform.Aiming at the problems of complicated structure,the usually method is to choose the same size of the each driving part,use the standard element connecting hinge.The calculation for motions and dynamics are obtained by Newton-Euler vector method.Which combing the theoretical research of the Stewart platform applied on the motion simulators.This paper inherits the dynamics theory of the Stewart platform,getting the dynamic vector equations by Newton-Euler vector method while the base station without stopping motion,which meaning and process are expressed cleared.The inverse kinematics and dynamics are relatively simple,but how to drive a motion with the rod's inertia moments,has become a major difficult problems during the solving process.Based on the above problems,this paper proposes a double Stewart extension configuration.Which the upper structure is a Stewart stable platform,the lower structure is a Stewart motion simulator.The motion simulator can accord to the working condition of stable platform,simulating the motion form of various interference sources,then appling to the fixedly connected plaform with the upper stable platform.The structure can be very convenient to carry out simulation tests of the stable platform in the laboratory environment.The dynamic problem should be solved first by analyzing the kinematics and dynamics of the connecting rods.Then the constraint between the connecting rods and the and the load platform can be obtained.By the last,the ultimate goal of solving stable platform system dynamics can be achieved.In this paper,the main research purposes is to solve the motion and dynamic equations of double structure stable platform system,and through the MATLAB programming and CATIA-ADAMS modeling and simulation,verified the correctness of dynamics formula.And also a detailed analysis on the reasons of error and precision is done.This work also makes a certain depth summary of the problems of the system construction and its evaluation criteria,the basic knowledge of the multi rigid body dynamics and spatial coordinate transformation and the work space.Through this research work,we can have a whole understanding of the basic theory of stable platform system.