Mr. Yu Xu Profile

Yu Xu

SPIE Involvement:

Author

Publications (2)

This will count as one of your downloads.

You will have access to both the presentation and article (if available).

DOWNLOAD NOW

This content is available for download via your institution's subscription. To access this item, please sign in to your personal account.

Email or Username Forgot your username?

Password Forgot your password?

Show

Keep me signed in

No SPIE account? Create an account

Proceedings Article | 6 September 2024 Poster + Paper

Precise feedback control of optic fiber positioning system based on time synchronization algorithm in LAMOST

Menghao Wang, Yu Xu, Chao Zhai

Proceedings Volume 13100, 131006K (2024) https://doi.org/10.1117/12.3018123

KEYWORDS: Control systems, Feedback control, Optical fibers, Visualization, Design, Control systems design, Cameras, CCD cameras, Wireless communications, Digital image processing

Read Abstract +

LAMOST(Large Sky Area Multi-Object Fiber Spectroscopy Telescope) is an Extremely Large Active Reflective Schmidt Telescope. In present LAMOST control system, 4,000 optical fiber control units run to specific positions under the commands of control computer, completing the observation of 4,000 celestial bodies. In order to increase the observation efficiency significantly, the second generation of LAMOST system is designed. In the new system, optical fiber control unit is miniaturized, and increased from 4,000 to 12,000. ZigBee wireless communication in former system is replaced completely by CAN bus communication, increasing the system’s efficiency and stability. The most significant problem of the new system is how to realize real-time precise feedback control of so many control units. In order to solve this problem, we introduced a time synchronization algorithm based on PTP(Precision Time Protocol) into the system. This algorithm realizes precise time synchronization among the upper computer, primary control nodes, subordinate control nodes and control units, thus obtains the planned operation status of each control unit. CCD cameras are used to capture the real-time operation status of control units and transmit the images to upper computer, which are processed and compared with the planned status. Then the control computer sends follow-up commands to control units to compensate the calculated errors. This makes it possible to realize precise feedback control on each control unit, avoiding common problems such as mispositioning and collision.

Proceedings Article | 26 August 2024 Poster + Paper

Real-time fiber positioning strategy based on FPGA in LAMOST

Guifeng Chen, Yu Xu, Chunhui Su, Menghao Wang, Chao Zhai

Proceedings Volume 13100, 131006L (2024) https://doi.org/10.1117/12.3018171

KEYWORDS: Cameras, Imaging systems, Detection and tracking algorithms, Process control, Metrology, Image segmentation, Field programmable gate arrays, Prototyping, Distortion, Control systems

Read Abstract +

With the development of spectral survey project, many large spectroscopic surveys are implementing closed-loop control fiber positioning system with a metrology camera system. The LAMOST improvement project plans to adopt a metrology camera system to update open-loop control to closed-loop control. To improve spectrum acquiring rate, the new generation of LAMOST being build is pursuing miniaturization and high-density of fiber positions, which takes more iteration time and is more likely to collide. Considering this situation, this paper presents a brand-new and real-time fiber positioning strategy with a fast fiber position recognition algorithm based on FPGA. A hardware acceleration platform is built on the main control board to process images of fiber positioners and calculate positions of each fiber every 17ms throughout the overall configuration. Then the main control board re-issues operation instructions to positioners based on the information, ensuring that positioners can update its running steps and speed in real time. When the offset of positioner’s actual position from target position is less than expected value (10um), the configuration is finished. This real-time control strategy can shorten configure time by positioning fibers in one time. And it can let two motors stop at the same time and avoid starting error, improving position accuracy. A prototype measurement platform was set up to verify the scientific validity of this strategy. After tests and validation in a laboratory environment, the results have shown that the time of fiber configuration is reduced by 1/5 and 100% of positioners can reach a precision of 10μm with great stability.

My Library

You currently do not have any folders to save your paper to! Create a new folder below.

Folder Name

Folder Description

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks. You are receiving this notice because your organization may not have SPIE eBooks access.*

*Shibboleth/Open Athens users─please sign in to access your institution's subscriptions.

To obtain this item, you may purchase the complete book in print or electronic format on SPIE.org.

ORGANIZATIONAL
Sign in with credentials provided by your organization.

Organizational Username

Organizational Password

Show/Hide Password

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available

Members:

Non-members: ADD TO CART

Keywords/Phrases

Search In:

Publication Years