A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems
For earth observation, the optical systems in small satellites are crucial to obtain high- resolution images. However, the alignment between a primary and a secondary mirror in an optical system can be disturbed due to the harsh environments inside vehicles or space (i.e., vibrations, shock loading...
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MDPI AG
2020-10-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/10/20/7087 |
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| author | Jinwon Jung Nguyen Van Sy Dongkyu Lee Seonggun Joe Jaihyuk Hwang Byungkyu Kim |
| author_facet | Jinwon Jung Nguyen Van Sy Dongkyu Lee Seonggun Joe Jaihyuk Hwang Byungkyu Kim |
| author_sort | Jinwon Jung |
| collection | DOAJ |
| description | For earth observation, the optical systems in small satellites are crucial to obtain high- resolution images. However, the alignment between a primary and a secondary mirror in an optical system can be disturbed due to the harsh environments inside vehicles or space (i.e., vibrations, shock loading during launch, dramatic temperature changes, or high vacuum pressure in space). To compensate for such undesired deformations, a focusing mechanism should be embedded into the optical system. In this paper, we propose a novel Single Motor-Driven Focusing mechanism with Flexure Hinges (SMFH), allowing the Flexure Hinge (FlexHe) to displace in the longitudinal direction. The presented FlexHe incorporates radial zig-zag-patterned slits to achieve flexibility, and preloading of the hinge structures to reduce the resulting hysteresis. To investigate an optimal configuration of FlexHe, a numerical simulation is performed by means of ANSYS 19.2. The variation of Modulation Transfer Function (MTF), corresponding to an image resolution, is evaluated by using an optics simulation program (CODE-V). The experimental setups are built by exploiting the fabricated SMFH and five LVDT (Linear Variable Differential Transformer) sensors with a high resolution of 0.031 µm. As a result, hysteresis can be reduced up to 6.52% with a pre-stretched length of 3 µm. The proposed SMFH allows not only the De-space to displace up to 23.93 µm, but also the De-center and the Tilt to achieve the desired displacements of 5.20 µm and 88.45 µrad, respectively. Conclusively, the SMFH shows promising characteristics to embed a feedback control, due to its high resolution (up to 0.1 µm) for De-space with the MTF of 37%. |
| first_indexed | 2024-03-10T15:41:45Z |
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| id | doaj.art-bce6ffb659b242e49c0ee8968ef268d2 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-10T15:41:45Z |
| publishDate | 2020-10-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-bce6ffb659b242e49c0ee8968ef268d22023-11-20T16:46:33ZengMDPI AGApplied Sciences2076-34172020-10-011020708710.3390/app10207087A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical SystemsJinwon Jung0Nguyen Van Sy1Dongkyu Lee2Seonggun Joe3Jaihyuk Hwang4Byungkyu Kim5Department of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang-si 10540, Gyeonggi-do, KoreaDepartment of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang-si 10540, Gyeonggi-do, KoreaSchool of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang-si 10540, Gyeonggi-do, KoreaCenter for the Micro-BioRobotics, Istituto Italiano di Tecnologia (IIT), 56025 Pontedera, ItalySchool of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang-si 10540, Gyeonggi-do, KoreaSchool of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang-si 10540, Gyeonggi-do, KoreaFor earth observation, the optical systems in small satellites are crucial to obtain high- resolution images. However, the alignment between a primary and a secondary mirror in an optical system can be disturbed due to the harsh environments inside vehicles or space (i.e., vibrations, shock loading during launch, dramatic temperature changes, or high vacuum pressure in space). To compensate for such undesired deformations, a focusing mechanism should be embedded into the optical system. In this paper, we propose a novel Single Motor-Driven Focusing mechanism with Flexure Hinges (SMFH), allowing the Flexure Hinge (FlexHe) to displace in the longitudinal direction. The presented FlexHe incorporates radial zig-zag-patterned slits to achieve flexibility, and preloading of the hinge structures to reduce the resulting hysteresis. To investigate an optimal configuration of FlexHe, a numerical simulation is performed by means of ANSYS 19.2. The variation of Modulation Transfer Function (MTF), corresponding to an image resolution, is evaluated by using an optics simulation program (CODE-V). The experimental setups are built by exploiting the fabricated SMFH and five LVDT (Linear Variable Differential Transformer) sensors with a high resolution of 0.031 µm. As a result, hysteresis can be reduced up to 6.52% with a pre-stretched length of 3 µm. The proposed SMFH allows not only the De-space to displace up to 23.93 µm, but also the De-center and the Tilt to achieve the desired displacements of 5.20 µm and 88.45 µrad, respectively. Conclusively, the SMFH shows promising characteristics to embed a feedback control, due to its high resolution (up to 0.1 µm) for De-space with the MTF of 37%.https://www.mdpi.com/2076-3417/10/20/7087small satelliteoptical systemfocusing mechanismsingle actuatorflexure hingestructure optimization |
| spellingShingle | Jinwon Jung Nguyen Van Sy Dongkyu Lee Seonggun Joe Jaihyuk Hwang Byungkyu Kim A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems Applied Sciences small satellite optical system focusing mechanism single actuator flexure hinge structure optimization |
| title | A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems |
| title_full | A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems |
| title_fullStr | A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems |
| title_full_unstemmed | A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems |
| title_short | A Single Motor-Driven Focusing Mechanism with Flexure Hinges for Small Satellite Optical Systems |
| title_sort | single motor driven focusing mechanism with flexure hinges for small satellite optical systems |
| topic | small satellite optical system focusing mechanism single actuator flexure hinge structure optimization |
| url | https://www.mdpi.com/2076-3417/10/20/7087 |
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