The Research Of Control System Of Astronomical Telescope Based On EPICS

With the development of electronic technology and computer technology, the telescope equipment becomes larger and more complicated since the first astronomical telescope combined by Galileo at1609. Now the largest diameter of radio telescope in construction is500meters. It is conceivable that such a large telescope will have a quite complex control system, and need multiple computers to operate together. Each computer control different part of the telescope. These computers will compose a control area network, so the large telescope control system is distributed. The control system is divided into three layers, the top layer is mainly maintain the entire observations of telescope, but the layer of bottom is specific controlling each kind of hardware, and the middle layer will transmit the operations from the top to the bottom. The large telescope equipment is designed and implemented by the different research institutions, then the collaborative work between different research institute and their devices is particularly important. In addition, due to the complexity of the telescope equipment, telescope control requires a very well hardware real-time control, the lower layer hardware device needs to receive real-time command from the top layer and make the appropriate changes. The same for top layer control system, receiving feedback of hardware must also have a well real-time control. Only in this way it can be a closed-loop control based on the state of the telescope in real-time. Most related telescope control system equipment research institute has its own characteristic control system and develop with different software technology and platform. In the integration of control system of large telescope, the central control system needs to do different things for different types of equipment to communicate with different device.Response to such circumstances, the modern telescope control system has two very important requirements, real-time and distributed. We need develop a very well real-time and distributed control software system for astronomical telescope. The Experimental Physics and Industrial Control System (EPICS) framework is designed to meet the real-time for control system of the large-scale physics experimental device, so it should have very well real-time ability. The number of command burst in the EPICS control system can be achieved several thousand times per second. EPICS also can be directly embedded in hardware devices so that it will have more real-time control. In the five-hundred-meter aperture spherical radio telescope (FAST) active reflective surface control system experiment, we adopt the EPICS framework to design and implement control system, and we successful test it on Miyun model of FAST. We also used EPICS technology in the small telescope project in Antarctica. Developing EPICS control program for each device, and modifying the source of the small telescope control system framework-RTS2(Remote Telescope System,2nd Version), so that it can access the IOC (Input/Output controller) device control program, and can control these devices in RTS2centralized. The integrated system will not only have the real-time of EPICS, but also the independent control and remote operation characteristics of RTS2.In this paper the main work is as follows:1. Detail description of EPICS framework and architecture, including functions and tools of each part of EPICS. Finally introduce the application of EPICS in large experimental device control system.2. The design of active reflector surface of FAST control program based on EPICS. Realize IOC program for FAST local control unit, and test on the Miyun model ofFAST.3. Based on the open source of small telescope control system RTS2, modifying its source to access IOC typed equipment control program, and realizing the original function of RTS2. Test it on the small telescope in the department of astronomy in USTC using the modified control system.