Kinematic Optimization And Accuracy Analysis Of A 2-DoF Rotational Parallel Mechanism Based On CGA

In order to meet requirements of the angle tracking mechanisms with the development of aerospace engineering,this thesis carries out the mobility analysis,kinematic analysis and optimal design,error modeling and verification,error independence analysis and sensitivity analysis of a 2 degree-of-freedom(DoF)parallel pointing mechanism.The following contributions have been made.1.Mobility analysis.Based on Conformal Geometric Algebra,the motions and constraints are determined.Then,the number and type of DoF as well as accessible motions are obtained.2.Kinematic analysis and optimal design.The inverse and forward position solutions are obtained by taking advantage of Conformal Geometric Algebra,and two indices of singularity are defined to identify singular configurations of a 2-DoF parallel pointing mechanism,and then the workspace of it is obtained by means of the boundary search algorithm.Considering all constrained conditions and formulating the objective function on the basis of the global kinematic performance indices,the kinematic optimal design of a 2-DoF parallel pointing mechanism is carried out by means of NSGA-II.3.Error modeling and verification.Resorting to Conformal Geometric Algebra,the geometric error model of a 2-DoF parallel pointing mechanism is formulated by considering all possible geometric errors.Furthermore,a novel validation method through simulation in SolidWorks software is proposed.By introducing geometric errors to the nominal virtual prototype,the formulated error model is proved to be accurate.4.Error independence analysis and sensitivity analysis.Based upon the error model,the number of independent geometric error is obtained after analyzing the redundancy and independence of geometric errors.Sensitivity analysis of all independent geometric errors is carried out based upon Monte Corlo method which provides the foundation for the kinematic calibration.The aforementioned work provides theoretical and technological support the application of the 2-DoF parallel pointing mechanism in the area of space angle tracking mechanism.