Optimization Design And Experimental Verification Of 5-dof Grating Tiling Parallel Device

With the development of new energy, astrophysics and other fields, close attention has been paid to the manufacture of large-size grating by scholars at home and abroad. In general, the large-size grating is fabricated by the method of mechanical tiling with small aperture gratings. The parallel mechanism is widely applied into the mechanical tiling device of grating due to its advantages of high rigidity, strong bearing capacity, fast response and high precision. At present, there are few researches on the design theory of the parallel mechanism of grating tiling. Therefore, the research on the design of the parallel mechanism is of great practical significance and research value.Firstly, according to the requirements of the degree of freedom and the kinetic property for the mechanism of grating tiling, the configuration synthesis of the parallel mechanism based on the virtual chain method is obtained. Then the optimal configuration of the tiling mechanism is obtained by determining the types of kinematic chains, the number and form of branched motion chains considering the requirements of heavy load, high precision and high stability during the tiling process where the manufacture difficulty degree, economy and other factors are taken into account as well.According to the requirements of mechanism optimization for grating tiling, the objective functions of workspace and stiffness for the grating tiling mechanism are respectively constructed by the inscribed rectangle area when the attitude angles is 0 and the stiffness matrix model based on the Jacobian matrix. Regarding the structure parameters of the parallel mechanism as the joints, the influences of the structure parameters on the objective functions are analyzed. And then the structure parameters that greatly affect the objective functions are chosen as the variables for optimal design to optimize the grating tiling mechanism. The results of the mechanism optimization which satisfy the request of objective functions are considered as the basis of the structure design of the mechanism.Based on the mechanism optimization results of the lengths of branched chains and the layout of hinge points, the design of the experiment device is completed by determining the structure sizes of the active branched chains, the moving platform and the frame. Firstly, the design calculation and mechanical analysis of the branched and flexible parts of the mechanism are carried out. Then the static simulation and modal simulation of the whole grating tiling mechanism are made to verify the feasibility of the mechanism. Finally, the effects on the static deformation and modal of the mechanism by different positions of the passive branched chains are compared to optimize the passive branched chains. And the optimization of the grating tiling mechanism is accomplished.The displacement characteristics of the micro drive part of the piezoelectric ceramic are tested, and the input and output characteristics of the micro drive part are analyzed as well. The control experiment of motion precision and the test experiment of the open loop stability are carried out on the grating tiling parallel device. The experimental results show that the movement precision and the open loop stability of the grating tiling parallel device meet the requirements of the actual engineering.