Abstract Details
| Name: Prasanna Deshmukh Affiliation: Indian Institute of Astrophysics Conference ID: ASI2017_428 Title : Wind disturbance effect on PSMT Segment Support Actuator - Modeling and Control Authors and Co-Authors : Padmakar Parihar, Indian Institute of Astrophysics,Bangalore. Deepta Sundar Mishra, Manipal Institute of Technology, Manipal, Karnataka. Vedashree, Christ University, Bangalore. Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : Upcoming Extremely large telescopes are based on segmented mirror technology. Small hexagonal segments placed side by side forms the large monolithic surface and need to be maintained against external disturbances like wind, gravity, temperature and structural vibration. This is achieved by using three position actuators per segment working at few-nanometer scale range along with a closed loop controller. Understanding the disturbances is essential for the design of different components of the SMT such as segment support actuators, segment support assembly, primary mirror control systems, etc. This paper explores the effect of wind disturbance on the position actuators of the Prototype Segmented Mirror Telescope (PSMT) under design at IIA Bangalore. The segment support actuators are primarily responsible for correcting the wind disturbances on PSMT. Initially for actuator modeling purpose, we used the first principle approach and represented it as a state space model. This enables us to develop a MIMO (multiple-input and multiple-output) model of the actuator, so as to include the wind disturbance force as one of the inputs along with the position/voltage command to the actuator. Further, in order to make the study more realistic, we obtained 1-year wind data collected at Indian Astronomical Observatory, Hanle. From this data, important wind parameters like mean speed and spectral characteristics are obtained and are used to fine-tune the analytical model of the wind flow. The drag coefficient (structure dependent parameter) due to wind flow over the telescope is estimated using wind tunnel simulation. The developed wind model is further utilized to generate time domain wind data with appropriate spectral representation at the desired height. This wind generator along with the PSMT actuator model is integrated using Matlab/Simulink to study the effect of wind disturbance on PSMT actuator. By undertaking such studies we get a step closure to predicting the worst-case wind scenario for future telescope design and simulation. In this paper, we present our simulation results and findings. |