Sinthysis And Optimal Dezign Of A Novel Asymmetrical Parallel Two-dimensional Pointing Mechanism With Redundant Actuation

The spatial pointing mechanism refers to the special space mechanism that drives the preload to realize the rotation and location in the space environment.It can achieve the functions of searching,tracking and pointing the target.It is mainly applied to satellite communication,space radar and space observation equipment.In recent years,with the increase of the function of the space effective load,the movement of the pointing mechanism is becoming more and more complex,and the performance requirements for the pointing mechanism are becoming increasingly strict.The traditional spatial pointing mechanism is in series form,such as X-Y type,azimuth-elevation type.Compared with series connection,parallel pointing mechanism has a series of advantages such as high rigidity,high accuracy,high load capacity and fast response speed.It has high research value.In view of the advantages of the parallel mechanism and the design requirement of the pointing mechanism,a new type of asymmetrical parallel two-dimensional pointing mechanism with actuation redundancy is proposed based on the spherical 5R mechanism.First of all,in order to eliminate the internal singularity of the spherical 5R mechanism,redundant drive limbs of the spherical 5R mechanism are synthesized,and a variety of limbs which have specific drive screws are obtained.A limb with simple structure and large working range is screened from above-mentioned limbs,and is combined with the spherical 5R mechanism into a new parallel two-dimensional pointing mechanism with redundant actuation.Secondly,the parasitic motion,the position inverse solution,Jacobi matrix and singularity of the mechanism are analyzed,and the singular trajectories of the mechanism are plotted through software simulation.Then,the performance atlas of the workspace,dexterity and bearing capacity are drawn,the optimal design of the size parameters of the mechanism has been done based on mechanism performance mean index and variance index,and a new kind of parallel pointing mechanism with excellent performance is obtained.Finally,aiming at the design requirements of the space pointing mechanism,a parallel two-dimensional spatial pointing mechanism with redundant actuation is designed,including the scheme design of the mechanism,the selection of key components,the design of main structures and the finite element analysis of mechanisms.In this paper,a new type of asymmetrical parallel two dimensional pointing mechanism with redundant actuation is designed.It has the advantages of high accuracy,high load capacity,large workspace and no internal singularity.It provides a high quality mechanism for the field of space tracking and pointing.