Aiming at the lack of prior information and the characterization difficulties of unanticipated state detection in the drive systems of astronomical telescope, the paper proposes a Multi-layer General Process Model for the recognition of telescope drive system state. Firstly, based on the prior information of state recognition, this paper refines the classification of anticipated state and unanticipated state. Then, focusing on the comprehensive description of the state of the telescope drive system, a Multi-layer General Process Model for the recognition of unanticipated state is established. Finally, the model is evaluated by using an example of Antarctica Survey Telescope drive system and excellent results have been obtained. The study of unanticipated state is the deepening and upgrading of anticipated, and it is an extension of fault diagnosis technology.
Due to the high complexity of the system and the variety of influencing factors of large astronomical telescopes, the current control system could be improved largely. It’s difficult for traditional automatic control technologies to ensure reliable and highly efficient operation. The key problem is such a system which needs to consider not only the various internal factors but also the various external factors. In addition, some factors are difficult to be digitized. Thus, it’s hard to make mathematical models to represent such complex and dynamic systems. The first goal of this project is to construct a software experimental platform for the intelligentization. The second goal is to develop an intelligent reliability management system, and an optimization system for observation quality. These application systems will be running using the historical data of LAMOST operation. The evaluation of such systems will be based on the simulation of these data.
More and more astronomical instruments have been installed in extreme environment such as Antarctica because of good seeing. However it’s not good for electromechanical system of astronomical telescope due to the harsh environment. This paper presents the study of the unanticipated states of direct drive system of extremely large telescope in extreme environment. The unanticipated states which are short of priori knowledge will degrade the reliability of monitor system significantly and put the self-diagnosis system into trouble.
More and more astronomical instruments have been installed in Antarctica because of good seeing. Due to adverse circumstances, remote location and unattended, a high fault rate was found in these astronomical instruments in Antarctica. To ensure the reliable operation of these instruments is one of critical technology problems. This paper presents an experimental platform with semi-physical simulation technique for Antarctic Telescopes. The platform helps the research for fault detection, fault diagnosis method, fault handling and so on. It consists of fault simulation system and fault diagnosis and self-recovery system. Furthermore, the platform can be used as fault diagnosis unit for Antarctic telescope directly.
This paper presents an expert system fault diagnosis and seamless self-healing scheme based on artificial intelligence, which is used for the astronomical telescope drive system. For the faults that have already occurred, the expert system inference mechanism can be used to realize quick localization of failure, and we can use the expert solution in the knowledge base to run the self-healing decision until the failure is resolved. For the failure the knowledge base doesn’t have, we can use human-machine interface to achieve real-time update of the knowledge base. For the faults that didn’t occurred, the trained adaptive BP neural network is used to fit the parameters of the telescope running status, to monitor the running status of the telescope in real time and to realize the fault warning of the telescope operation. Fault diagnosis and seamless self-healing technology is one of the key technologies to realize intelligent, its research is of great significance.
Due to its extremely cold, dry, tenuous, and stable atmosphere, the Antarctica plateau is widely considered to be an excellent astronomical site. The long periods of uninterrupted darkness at polar sites such as Dome A provide a possibility of continuous observation for more than 3 months, which is quite suitable for time-domain astronomy. The second Antarctic Survey Telescope (AST3-2), the largest optical telescope in Antarctica so far, is a 0.5m entrance diameter large field of view optical imaging telescope which was deployed to Dome A, Antarctic in January 2015. It was used to study variable objects, such as supernova explosions and the afterglow of gamma-ray bursts, and to search for extrasolar planets. For the remoteness of the Antarctic plateau, it is designed to observe autonomously and operate remotely via satellite communication. With only 20 days attending maintenance annually, it has experienced 3 winters. It has observed for 3months in 2015 and 4 months in 2016. In the third year of 2017, the observing time of AST3-2 has covered all the polar night from March to September, the data reached to nearly 30TB with more than 200,000 exposures for searching supernovas and exoplanets. AST3-2 was also the only one telescope in the Antarctic plate that joined the optical observations of LIGO GW170817.
The site testing shows that Antarctic Dome A is one of the best site on earth for astronomical observations, for wavelength ranging from visible to infrared and sub-millimeter. Continuous observation for nearly four months in polar nights makes Dome A quite suitable for time domain astronomy. In the past decade CCAA already led a series of Antarctic astronomy activities and telescope projects which will be introduced in this paper. The first generation telescope is Chinese Small Telescope Array known as CSTAR, which was composed of four identical telescopes with 145mm entrance pupil, 20 square degrees FOV and different filters, all pointing to the celestial South Point, mainly used for variable stars detection and site testing. The telescope was deployed in Dome A in Jan. 2008, and followed by automatic observations for four consecutive winters. Three Antarctic Survey Telescopes (AST3) is the second generation telescope capable of pointing and tracking in very low temperature, with 500mm entrance pupil, 8.5 square degree FOV. AST3-1 and AST3-2 were respectively mounted on Dome A in Jan. 2012 and 2015, fully remotely controlled for supernovae survey and exoplanets searching. In Aug. 2017, AST3-2 successfully detected the optical counterpart of LIGO Source GW 170817. Now AST3-3 is under development for both optical and near infrared sky survey by matching different cameras. Based on the experience of the above smaller sized optical telescopes, the 2.5m Kunlun Dark Universe Survey Telescope (KDUST) was proposed for high resolution imaging over wide field of view. Currently the KDUST proposal was submitted to the government and waiting for project review.
This paper puts forward a electronic fault diagnose method focusing on large-diameter astronomical telescope’s armature winding, and ascertains if it is the resistance or inductance which is out of order. When it comes to armature winding’s electronic fault, give the angular position a step signal, and compare the outputs of five models of normal, larger-resistance, smaller-resistance, larger-inductance and smaller-inductance, so we can position the fault. Firstly, we ascertain the transfer function of the angular position to the armature voltage, to analysis the output of armature voltage when the angular position’s input is step signal. Secondly, ascertain the different armature currents’ characteristics after armature voltage pass through different armature models. Finally, basing on the characteristics, we design two strategies of resistance and inductance separately. The author use MATLAB/Simulink function to model and emulate with the hardware parameters of the 2.5m-caliber telescope, which China and France developed cooperatively for Russia. Meanwhile, the author add a white noise disturbance to the armature voltage, the result shows its feasibility under a certain sized disturbance.
The Antarctic Survey Telescope-AST3 consists of three optical telescopes with 680mm primary mirror and 8 square degree field of view, mainly for observations of supernovas and extrasolar planets searching from Antarctic Dome A. The first two AST3 telescopes (AST3-1 and AST3-2) were successfully installed on Dome A by Chinese expedition team in Jan. 2012 and Jan. 2015 separately. Multi-anti-frost methods were designed for AST3-2 and the automatic observations are keeping on from March 2016. The best limited magnitude is 19.4m with exposure time 60s in G band. The third AST3 will have switchable interface for both optical camera and near infrared camera optimized for k dark band survey. Now the telescope is under development in NIAOT and the K-band camera is under development in AAO.
Chinese Antarctic Observatory has been listed as National large research infrastructure during twelfth five-year plan. Kunlun Dark Universe Survey Telescope, one of two major facility of Chinese Antarctic Observatory, is a 2.5-meter optic/infrared telescope and will be built at the Chinese Antarctic Kunlun Station. It is intended to take advantage of the exceptional seeing conditions, as well as the low temperature reducing background for infrared observations. KDUST will adopt an innovative optical system, which can deliver very good image quality over a 2 square degree flat field of view. All of parts of it have been designed carefully to endure the extremely harsh environment. KDUST will be perched on a 14.5-meter-high tower to lift it above the turbulence layer. In this paper, preliminary design and key technology pre-research of KDUST will be introduced.
The AST3 project consists of three large field of view survey telescopes with 680mm primary mirror, mainly for observations of supernovas and extrasolar planets searching from Antarctic Dome A where is very likely to be the best astronomical site on earth for astronomical observations from optical wavelength to thermal infrared and beyond, according to the four years site testing works by CCAA, UNSW and PRIC. The first AST3 was mounted on Dome A in Jan. 2012 and automatically run from March to May 2012. Based on the onsite winterization performance of the first AST3, some improvements such as the usage of high resolution encoders, defrosting method, better thermal control and easier onsite assembly et al were done for the second one. The winterization observation of AST3-2 in Mohe was carried on from Nov. 2013 to Apr. 2014, where is the most northern and coldest part of China with the lowest temperature around -50°. The technical modifications and testing observation results will be given in this paper. The third AST3 will be optimized from optical to thermal infrared aiming diffraction limited imaging with K band. Thus the whole AST3 project will be a good test bench for the development of future larger aperture optical/infrared Antarctic telescopes such as the proposed 2.5m Kunlun Dark Universe Survey Telescope project.
In recent years, Nanjing Institute of Astronomical Optics and Technology (NIAOT) has made several telescopes for
observatories all around the world. In 2011 NIAOT just finished the development of a 2.5m optical/infrared telescope
mount. First part of this paper is to introduce the mount structure and their adjustment work. Second part is to give an
introduction of the mount performance test methods and test results finished on NIAOT workshop.
Large Optical Antarctic Telescope, LOAT hereafter, is a new research hotspot nowadays. For example, a 2.5m KDUST, e.g. Kunlun Dark UniverSe Telescope is on anvil. It's difficult for main axis of large telescope tracking system to track the target precisely with ultra-low speed because of nonlinear disturbances due to unique ultra-low temperature. This paper presents these nonlinear disturbances.
This paper gives a summary on control strategies and algorithms for contemporary large astronomical optical telescopes.
The study lays emphasis on high precision tracking for large astronomical optical telescopes with large inertia, ultra-low
speed and multi-disturbance. The control strategies and algorithms of some telescopes based on direct drive or friction
drive are analyzed carefully. Finally, the future development in this field is presented.
Proc. SPIE. 7733, Ground-based and Airborne Telescopes III
KEYWORDS: Telescopes, Mirrors, Control systems, Computer programming, Astronomical imaging, Optical instrument design, Control systems design, Astronomy, Astronomical telescopes, Information technology
Telescope is a very important tool for astronomers to survey and study the stellar stars and astronomical phenomena. The
performance of a telescope is its capability to track the observing objects and keep the image on the field of view during
the observing period. All these functions will be achieved by telescope mount, including mount control system. The
mount is to support the mirror cell and keep the mirror cell position stability. Meanwhile, with the help of control
system, the mount acts as tracker of the observing objects. So, for a telescope, the mount and its control system play an
important role during the telescope operation. This paper gives an introduction of a mount structure designed for a 2.5m
optical/infrared telescope and the corresponding control system. Some of preliminary test results are also given in this
Astronomers are ever dreaming of sites with best seeing on the Earth surface for celestial observation, and the Antarctica
is one of a few such sites only left owing to the global air pollution. However, Antarctica region is largely unaccessible
for human being due to lacking of fundamental living conditions, travel facilities and effective ways of communication.
Worst of all, the popular internet source as a general way of communication scarcely exists there. Facing such a dilemma
and as a solution remote control and data transmission for telescopes through iridium satellite communication has been
put forward for the Chinese network Antarctic Schmidt Telescopes 3 (AST3), which is currently under all round research
and development. This paper presents iridium satellite-based remote control application adapted to telescope control. The
pioneer work in China involves hardware and software configuration utilizing techniques for reliable and secure
communication, which is outlined in the paper too.
Friction drive is used in some large astronomical telescopes in recent years. Comparing to the direct drive, friction drive
train consists of more buildup parts. Usually, the friction drive train consists of motor-tachometer unit, coupling, reducer,
driving roller, big wheel, encoder and encoder coupling. Normally, these buildup parts will introduce somewhat errors to
the drive system. Some of them are random error and some of them are systematic error. For the random error, the
effective way is to estimate their contributions and try to find proper way to decrease its influence. For the systematic
error, the useful way is to analyse and test them quantitively, and then feedback the error to the control system to correct
them. The main task of this paper is to analyse these error sources and find out their characteristics, such as random error,
systematic error and contributions. The methods or equations used in the analysis will be also presented detail in this
Proc. SPIE. 7019, Advanced Software and Control for Astronomy II
KEYWORDS: Stars, Control systems, Control systems design, Telescopes, Astronomical telescopes, Global Positioning System, Charge-coupled devices, Astronomical imaging, Computing systems, Telecommunications
The Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST hereafter, will become an
astronomical telescope with largest field of view and most efficient observation in 4-m aperture
telescopes in the world by its completion in 2008. In June 2007, Small System for LAMOST was
completed successfully. Small LAMOST is composed of mirror with aperture of 3 meter(effective
aperture of 2 meter ) 250 fibers one spectrograph two 4kx4k CCD camera tracking and controlling
system. This paper presents the study in Small LAMOST. It comprises three main parts. First, it
introduces the software design for the control system of Small LAMOST, including Mount tracking,
Focal Plane tracking, GPS time ticking and time synchronization between computers, auto-guiding, etc.
The design has proved correct and feasible. Second, it describes some technical solutions to the
requirements of precision, real time and open architecture for Small LAMOST. Lastly, some
experimental data and curves are given to show the tracking precision of Small LAMOST.
Due to its high accuracy and good performance at low speed, friction drive is widely used in turntable
and large astronomical telescopes such as LAMOST and Keck. Especially, friction drives are
implemented on the axes of azimuth, altitude and field rotation in LAMOST telescope. This paper
describes the study on servo control system for friction drive with ultra-low speed and high accuracy.
The principle, constitution, control algorithm and realization of servo system based on friction drive are
analyzed and explored.
KEYWORDS: Control systems, Servomechanisms, Computer programming, Motion controllers, Control systems design, Telescopes, Astronomical imaging, Astronomical telescopes, Feedback signals, Analytical research
Taking as an example the focal plane control system for the largest optical telescope being built in our country, the paper focuses on Universal Motion and Automation Controller (UMAC) based servo control system with high accuracy, and analyzes its design scheme. The scheme analysis and preliminary test demonstrate a broad outlook of UMAC based application in complex control systems with high precision, real time, fast action, easy adaptation and open architecture.
A brief research summary and a preliminary test of the Focal Plane Control System (FPCS) are presented. The FPCS is one of components for the control system of Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST), which is a national large scientific project. The design scheme features distributed, hierarchical and expansible network architecture with UMAC based control technology. A number of advanced techniques are integrated with some control software and hardware, which presents a solution to requirements of precision, real time and open architecture for the
FPCS in the design of large optical astronomical telescopes.