A multi-scale deformation measurement method for large parabolic antenna surfaces based on shape sensing and ray tracing

Abstract

In the new era, large parabolic antennas are operating at increasingly higher frequencies, with deformations caused by time-varying loads such as temperature and wind receiving significant attention. Existing surface measurement methods struggle to meet the requirements for full-attitude, quasi-real-time, high-accuracy, and high-resolution measurements of large-aperture antennas. To address this challenge, we develop a multi-scale deformation measurement method based on shape sensing and ray tracing in this work. In the proposed method, the inverse finite element method (iFEM) is employed to provide small-scale deformation information of the panels, enabling shape sensing. The ray equations obtained through ray tracing and geometric continuity constraints are used to provide essential large-scale information for surface deformation measurement, specifically the rigid pose information of the panels. Simulation results using the TM-65 m antenna as an example demonstrate that the method can achieve measurement errors below 0.1 mm. Additionally, experiments are conducted on a self-built measurement system, where high-accuracy calibration was achieved using a camera-scanner fusion approach. The experimental results demonstrate that the proposed method achieves a measurement error of about 0.2 mm and a relative error of about 5%. The measurement time in the experimental setup is approximately 30 s, which is 1/20th of that required by the laser scanning method.