Real-Time Monitoring of the Position and Orientation of a Radio Telescope Sub-Reflector with Fiber Bragg Grating Sensors

Abstract

Environmental loads linked with pointing errors, such as gravity, thermal gradients, and wind disturbances, are a serious concern for large-aperture high-frequency radio telescopes. For the purpose of maintaining the pointing performance of a telescope, a contact measurement scheme is proposed on basis of fiber Bragg grating (FBG) strain sensors that can monitor the sub-reflector shift in real time as the input data of the adjustment system. In this scheme, the relationship between the in situ strain measurement and the deformation of the supporting structure, which is the main cause of sub-reflector shift, is deduced using the inverse Finite Element Method (iFEM). Finally, experimental studies are carried out on a simple physical structure model to validate the effectiveness and accuracy of the contact measurement scheme.

Hybrid Shell-Beam Inverse Finite Element Method for the Shape Sensing of Stiffened Thin-Walled Structures: Formulation and Experimental Validation on a Composite Wing-Shaped Panel

“…Later works feature formulations for slender beams [53], handling cross-sectional complexities [54,55], and composite structures [56]. Numerical and experimental application of the 1D iFEM feature the monitoring of circular and airfoil beams [54,57], radio telescope reflectors [58], wing structures [59], subsea pipelines [60], etc. Recent efforts have also been aimed at non-linear deformation monitoring [61] and optimal sensor placement [46,47,62] for efficient shape sensing.…”

Sardinia Radio Telescope structural behavior under solar thermal load

“…In the latter paper the problem is treated through an approach based on Finite Element (FE) method integrated with field measurements that allow to develop a model updating capable of reaching good accuracy. An example is proposed in (Zhao et al, 2019) in which the FE method is used to study of the effects on the pointing of radio telescopes caused by gravity, thermal gradients, and wind disturbances. In (Greve et al, 2005), temperature measurements are applied to finite element model in order to calculate structural deformation of the Institut de Radioastronomie Millimétrique 30-m telescope.…”