Star image tracking control system in the Lower Latitude Meridian Circle (LLMC)

Star image tracking in the LLMC is composed of two direction movements, that is, a horizontal tracking of the CCD chip (camera) and a vertical tracking of the telescope tube in the zenith distance. Based on an idea that the two tracking control systems should be incorporate. A new hardware structure of tracking control system in the LLMC is presented in this paper. The system can simultaneously output two gates of motor driving pulses, one for the CCD tracking in horizontal direction and another for the tube tracking in vertical direction or for the slow motion placement of the tube in vertical direction. Experiments indicate that the driving pulses output from the new system can be controlled more easily than those from old systems in software mode and its frequency can be higher. The programming methods for the ASM control program in the micro-controller system and for the C++ control program in the host PC are described. Some primary results and experiences from the experiments are also presented in the last.