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Keywords = subreflector actuator

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18 pages, 2333 KB  
Article
Robust Self-Calibration of Subreflector Actuators Under Noise and Limited Workspace Conditions
by Guljaina Kazezkhan, Na Wang, Qian Xu, Shangmin Lin, Hui Wang, Fei Xue, Feilong He and Xiaoman Cao
Machines 2025, 13(6), 484; https://doi.org/10.3390/machines13060484 - 3 Jun 2025
Cited by 1 | Viewed by 1014
Abstract
Accurate kinematic calibration of subreflector actuators is essential for pointing precision of large radio telescopes, particularly at high frequencies. Conventional least-squares methods are vulnerable to noise and outliers, and their accuracy may degrade when limited pose diversity leads to poor parameter excitation. To [...] Read more.
Accurate kinematic calibration of subreflector actuators is essential for pointing precision of large radio telescopes, particularly at high frequencies. Conventional least-squares methods are vulnerable to noise and outliers, and their accuracy may degrade when limited pose diversity leads to poor parameter excitation. To address these challenges, this paper proposes a novel robust self-calibration framework that integrates Huber loss and L2 regularization into the Levenberg–Marquardt (LM) algorithm—yielding a hybrid optimization approach that combines residual robustness, numerical stability, and convergence reliability. A comprehensive simulation study was conducted under varying workspace sizes and sensor noise levels. The proposed method maintained stable performance even under reduced excitation and high-noise conditions, where traditional LM methods typically degrade, confirming its robustness and applicability to realistic calibration scenarios. The framework was further validated using a structured-light 6-DOF pose measurement system, the proposed method achieved over 90% improvement in both position and orientation accuracy compared to the traditional LM approach. These findings confirm the method’s effectiveness for high-precision 6-DOF calibration in parallel mechanisms, and its suitability for real-world applications in radio telescope subreflector alignment. Full article
(This article belongs to the Section Machine Design and Theory)
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13 pages, 6278 KB  
Article
Active Adjustment of the Subreflector Shape for the Large Dual-Reflector Antenna
by Binbin Xiang, Tianxiang Zheng, Wei Wang, Peiyuan Lian, Guljaina Kazezkhan, Jianping Zhou and Kai Li
Micromachines 2023, 14(10), 1893; https://doi.org/10.3390/mi14101893 - 30 Sep 2023
Cited by 1 | Viewed by 2414
Abstract
A shape adjustment method for subreflectors based on minimizing the residual wavefront error of the large dual-reflector antenna is presented. This method is used to compensate for the antenna structural deformation caused by environment loading. The shape of the subreflector is adjusted using [...] Read more.
A shape adjustment method for subreflectors based on minimizing the residual wavefront error of the large dual-reflector antenna is presented. This method is used to compensate for the antenna structural deformation caused by environment loading. The shape of the subreflector is adjusted using actuators fixed under the panels. The shape adjustment response function for the subreflector shape and the actuators’ adjustment amount is established, which is based on the inverse distance weighting function, and then the control function of the subreflector shape is obtained. The actuators’ adjustment amount can be calculated using the least squares matrix transformation with the minimum residual wavefront error. Analysis of the experiment’s results shows the residual wavefront error and primary aberration are greatly reduced under different elevation angles, and the effectiveness of the proposed method is verified. Full article
(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)
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