The Optimization Of The Research For LAMOST Optical Fiber Positioning Control System

Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is an innovative reflecting Schmidt telescope which is designed and developed by Chinese scientists, promising a very high spectrum acquiring rate in the world. By using the parallel controllable fiber positioning technique, one of the key technologies, LAMOST has also been applied to international project called BigBOSS. It is both an opportunity and a challenge for China. In order to improve the walk accuracy of the optical fiber positioning unit and complete the calibration system of camera measurement, taking the improvement of accuracy as the core, all aspects of positioning accuracy be analyzed in the calibration process and suitably improved in accordance with the actual situation. The accomplished tasks are as follows:1. The polynomial camera calibration model is studied thoroughly in the Calibration application of the optical fiber positioning unit. It describes in detail the selection of calibration parameters in the model and how many points and how to take points to achieve the calibration precision with the corresponding parameters. Experimentally derived by taking the point, the precision calibration became higher with the right amount of increasing of the number of light points. Choosing20or30parameters to calibrate the camera should be based on the actual situation. In the same approach, the influence degree of the calibration accuracy affected by2KCCD and4KCCD has been compared.2. The best treatment for multiple photos was studied by polynomial fitting with30parameters for the calibration target spot. Multiple image data captured by the camera were processed and compared through seven kinds of treatment methods, it shows that the mean value of10continuous shooting pictures’data in the preprocessing as a set of data can attain relatively small error, and the calibration efficiency and accuracy were also improved.3. The Optimum Design of the stepper motor acceleration and deceleration curve based on the traditional S-curve model was optimized design, a new control method of S-curve of a single cubic equation was proposed. It has a small amount of computation and a simple equation. If the controlled object’s constraint is not the same, the corresponding curves can be only obtained by setting the initial parameters flexibly, such as the start frequency, the stable frequency, and the acceleration time. The curve discretion was used iso-pulse interval manner, and the frequency was calculated precisely by Newton iterative method. The optimal result was attained by repeated tests shows the final frequency group reduced the overshoot, improved stability, reduced the noise etc.4. The communication performance of Zigbee was simulated in high density sub-node communication. It shows that not only the written procedures of communication but also the specification of Zigbee related the communication problems. With the continued growth of Zigbee, the development of market demand and the standardization of communications programming, the problems will be improved effectively.