Development of a large-scale standard device for calibration of high-precision spherical coordinate scanning measurement systems

The rapid advancement of high-precision spherical coordinate scanning measurement systems (HP-SCSMSs) has significantly improved the efficiency and accuracy of profile measurements for complex curved parts, such as aircraft wings, fuselages, rocket bodies, and wind turbine blades. However, the calibration and performance evaluation of HP-SCSMSs remain challenging, as both internal geometric errors and external error sources can contribute to inaccuracies in the resulting 3D point clouds. To address these challenges, a large-scale curved surface standard device has been designed and assembled. This device provides a physical reference for evaluating HP-SCSMSs and facilitates comprehensive calibration of HP-SCSMSs. This paper details the design, assembly, and verification of the standard device. During the design phase, the careful consideration is given to the surface shape and the adjustment strategy for the surface panels to ensure the device could simulate a variety of scanning objects and conditions. To mitigate the effects of temperature changes on measurement accuracy, an innovative independent suspension and radial guide structure is implemented, effectively reducing the impact of thermal deformation. During assembly, advanced high-precision measurement techniques are employed to ensure the precise alignment and stability of each component. Finally, to verify the long-term stability of the standard device, three measurements of its concave panel using a laser tracker are taken over a period of nine months. The measured data are compared with the previously constructed model, showing a maximum Root Mean Square (RMS) of 0.009 mm. The developed large-scale standard device provides a reliable standard for evaluating and calibrating HP-SCSMSs, addressing both internal and external error sources, and lays the groundwork for the development and refinement of industry standards for HP-SCSMSs.