Prof. Xinqi Xu Profile

Prof. Xinqi Xu

Professor at NIAOT

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Author

Publications (15)

Proceedings Article | 4 August 2010 Paper

LAMOST control system: past and future

Xinqi Xu, Lingzhe Xu

Proceedings Volume 7738, 77381J (2010) https://doi.org/10.1117/12.856802

KEYWORDS: Control systems, Telescopes, Space telescopes, Astronomical telescopes, Astronomical imaging, Control systems design, Servomechanisms, Astronomy, Mirrors, Active optics

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Proceedings Article | 21 November 2007 Paper

Exact differentiator based sliding mode control for large optical astronomical telescopes

Wangping Zhou, Xinqi Xu, Zhiming Dong

Proceedings Volume 6721, 67210P (2007) https://doi.org/10.1117/12.782947

KEYWORDS: Control systems, Telescopes, Device simulation, Optical telescopes, Astronomy, Astronomical imaging, Astronomical telescopes, Switching, MATLAB, Servomechanisms

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Large astronomical optical telescopes are badly needed in order to learn more remote universe. There exist some key problems of the control systems of large astronomical optical telescopes. Since they have voluminous bodies that would encounter heavy external disturbance, one of the key problems is focused on how to accurately control them. Additionally, in order to get nicer ultra-low velocity performance and a steady field of view, friction drive is widely applied in contemporary large optical telescopes. One serious disadvantage of friction drive is that it will cause some nonlinear uncertainties to influence telescope controls because of the mechanical characteristics between the principal and subordinate friction wheels. These two aspects of external and internal disturbances will make a telescope very difficult to be controlled. In this paper, we introduce a method of higher order sliding modes (HOSM) to control telescopes, which overcome these two disadvantages of traditional Proportional-Integral-Derivative approach and can achieve excellent control performance. Conventional sliding mode approach has been applied in many other mechanical control systems owing to its high accuracy in anti-jamming. By discontinuous switching, it is invariable to disturbances based on keeping some constraints with a sufficiently energetic effort. However, such conventional sliding mode approach may cause dangerous high-frequency vibrations in the corresponding control system, which may influence systemic control performance or even lead the system unstable. In this work, we use the newly developed HOSM approach in the control systems of the large astronomical optical telescopes. The HOSM approach inherits the dominant merits of conventional sliding mode. Moreover, it acts on the higher order time derivatives of the system deviation from the constraint. And the discontinuous dynamics are restricted to the highest state while the counterpart in standard sliding mode is in first derivative. Thus the HOSM approach can mostly removes high-frequency vibration effects on telescope control. This control approach needs all states of the system to be observable. We use robust exact differentiator to estimate the immeasurable state. Simulations have been done in the environment of MATLAB language. The results show that this approach can realize the tracking performance of accurate ultra-low velocity for telescope control.

Proceedings Article | 6 July 2006 Paper

Study on H-Infinity control for LAMOST main axes

Wangping Zhou, Xinqi Xu, Zhiming Dong

Proceedings Volume 6273, 627333 (2006) https://doi.org/10.1117/12.671107

KEYWORDS: Control systems, Picosecond phenomena, Mathematical modeling, Systems modeling, Servomechanisms, Device simulation, Cesium, Astronomical imaging, Telescopes, MATLAB

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Proceedings Article | 27 June 2006 Paper

Remote wireless control for LAMOST telescope

Lingzhe Xu, Xinqi Xu

Proceedings Volume 6274, 62740W (2006) https://doi.org/10.1117/12.671085

KEYWORDS: Telescopes, Control systems, Global system for mobile communications, Astronomy, Mobile communications, Astronomical telescopes, Lithium, Astronomical imaging, Information technology, Cell phones

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Proceedings Article | 23 June 2006 Paper

Mount control system for the CFGT telescope

Xinqi Xu, Zhiming Dong, Wangping Zhou

Proceedings Volume 6267, 62672B (2006) https://doi.org/10.1117/12.671059

KEYWORDS: Telescopes, Computer programming, Control systems, Mirrors, Control systems design, Servomechanisms, Distortion, Computer aided design, Optical instrument design, Large telescopes

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Proceedings Article | 6 December 2005 Paper

Network control system of LAMOST telescope (Invited Paper)

Lingzhe Xu, Xinqi Xu

Proceedings Volume 6052, 605209 (2005) https://doi.org/10.1117/12.640498

KEYWORDS: Control systems, Telescopes, Databases, Mirrors, Active optics, Astronomical telescopes, Astronomy, Servomechanisms, Astronomical imaging, Opto mechatronics

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Proceedings Article | 6 December 2005 Paper

Motion control for LAMOST focal plane

Xinqi Xu, Shihai Yang

Proceedings Volume 6052, 60520N (2005) https://doi.org/10.1117/12.640494

KEYWORDS: Control systems, Servomechanisms, Computer programming, Motion controllers, Control systems design, Telescopes, Astronomical imaging, Astronomical telescopes, Feedback signals, Analytical research

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Proceedings Article | 29 September 2004 Paper

Lesson and experience learned from tracking test of LAMOST model mount

Xinqi Xu, Hai Wang, Yizhong Zeng

Proceedings Volume 5495, (2004) https://doi.org/10.1117/12.550927

KEYWORDS: Computer programming, Mirrors, Stars, Telescopes, Servomechanisms, Astronomical imaging, Image segmentation, Electronics, Charge-coupled devices, Astronomical telescopes

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Proceedings Article | 28 September 2004 Paper

Preliminary considerations for CFGT control system

Xinqi Xu, Chunhua Yan

Proceedings Volume 5489, (2004) https://doi.org/10.1117/12.550972

KEYWORDS: Control systems, Telescopes, Computer programming, Databases, Image processing, Image segmentation, Astronomical telescopes, Mirrors, Servomechanisms, Network architectures

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Proceedings Article | 28 September 2004 Paper

Experiment system of LAMOST active optics

Xiangqun Cui, Ding Su, Guoping Li, Zhengqiu Yao, Zhengcao Zhang, Yeping Li, Yong Zhang, You Wang, Xinqi Xu, Hai Wang

Proceedings Volume 5489, (2004) https://doi.org/10.1117/12.552426

KEYWORDS: Mirrors, Active optics, Wavefronts, Actuators, Wavefront sensors, Telescopes, Control systems, Segmented mirrors, Deformable mirrors, Spherical lenses

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Proceedings Article | 15 September 2004 Paper

Application of real time database to LAMOST control system

Lingzhe Xu, Xinqi Xu

Proceedings Volume 5496, (2004) https://doi.org/10.1117/12.550999

KEYWORDS: Databases, Human-machine interfaces, Control systems, Telescopes, Computer programming, Data communications, Astronomical telescopes, Digital signal processing, Data storage, Servomechanisms

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Proceedings Article | 4 February 2003 Paper

GPS-based timing system for LAMOST

Xinqi Xu, Gangping Jin

Proceedings Volume 4837, (2003) https://doi.org/10.1117/12.456726

KEYWORDS: Global Positioning System, Receivers, Control systems, Clocks, Telescopes, Servomechanisms, Mirrors, Astronomical imaging, Astronomy, Active optics

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Proceedings Article | 4 February 2003 Paper

Overview of LAMOST control system

Xinqi Xu, Lingzhe Xu, Gangping Jin

Proceedings Volume 4837, (2003) https://doi.org/10.1117/12.456722

KEYWORDS: Control systems, Telescopes, Active optics, Stars, Device simulation, Astronomical telescopes, Servomechanisms, Actuators, Image segmentation, Computer simulations

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Proceedings Article | 30 July 2002 Paper

Software simulation of the LAMOST control system

Xinqi Xu, Jun Zhou, Lingzhe Xu

Proceedings Volume 4757, (2002) https://doi.org/10.1117/12.489818

KEYWORDS: Device simulation, Telescopes, Control systems, Active optics, Human-machine interfaces, Software engineering, Astronomical imaging, Stars, Computer programming, Astronomy

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Proceedings Article | 9 June 1994 Paper

Current status of the IOTA interferometer

Nathaniel Carleton, Wesley Traub, Marc Lacasse, Peter Nisenson, Michael Pearlman, Robert Reasenberg, Xinqi Xu, Charles Coldwell, Alexander Panasyuk, James Benson, Costas Papaliolios, Read Predmore, F. Peter Schloerb, H. Dyck, David Gibson

Proceedings Volume 2200, (1994) https://doi.org/10.1117/12.177236

KEYWORDS: Telescopes, Mirrors, Sensors, Beam splitters, Infrared radiation, Stars, Visibility, Interferometry, Infrared telescopes, Visible radiation

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The first two telescopes of the Infrared-Optical Telescope Array (IOTA) project are now in place and yielding data at the Smithsonian Institution's F. L. Whipple Observatory on Mt. Hopkins, near Tucson, Arizona. The IOTA collectors are 45 cm in diameter, and may be moved to various stations in an L-shaped configuration with a maximum baseline of 38 m. A third collector will be added as soon as funding permits. Each light-collector assembly consists of a siderostat feeding a stationary afocal Cassegrain telescope that produces a 10-X reduced parallel beam, which is in turn directed vertically downward by a piezo-driven active mirror that stabilizes the ultimate image position. The reduced beams enter an evacuated envelope and proceed to the corner of the array, where they are turned back along one arm for path compensation. The delay line, in one beam, consists of two parts: one dihedral reflector positioned in a slew-and-clamp mode to give the major part of the desired delay; and a second dihedral mounted on an air-bearing carriage to provide the variable delay that is needed. After delay, the beams exit from the vacuum and are directed by dichroic mirrors into the infrared beam-combination and detection system. The visible light passes on to another area, to the image-tracker detectors and the visible-light combination and detection system. The beams are combined in pupil-plane mode on beam splitters. The combined IR beams are conveyed to two cooled single-element InSb detectors. The combined visible-light beams are focussed by lenslet arrays onto multimode optical fibers that lead to the slit of a specially-designed prism spectrometer. For the visible mode, the delay line is run at several wavelengths on one side of the zero- path point, so that several cycles of interference occur across the spectrum. First results were obtained with the IR system, giving visibilities for several K and M stars, using 2.2 micrometers radiation on a N-S baseline of 21.2 m. From these measurements we obtained preliminary estimates of effective stellar diameters in the K band.

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