The Research of Deformation on Load about the Terminal Instruments Derotator Platform of NVST

The deformation on load about the terminal instruments derotator platform of NVST is researched. When the upper platform is measured, the Laser light source is placed on the center of the platform and pointed to the CCD camera which is placed on the edge of the cantilever in the periphery platform. The centroid of the spot on the CCD target is computed using the centroid algorithm, whose variation presents the deformation. The deformation of gravity direction is researched. The direction of gravity is taken as X axis and the horizontal direction is taken as Y axis which is only for reference. Through multiple sets of experiments and the simulation by ANSYS, it is found that the centroid data of all cantilevers is obviously inconsistent when the derotator platform forward and reverse in the range of 80-200 degree, which is casued by the inconsistency of the drive plane and the positioning plane, and the roller group is not strictly pointing towards the center:One of the cantilevers is sensitive to the load and its rigidity is worse than others, another cantilever is sensitive to the load in some areas, while both have poor stiffness of the connection with the central turntable.