Abstract Details
| Name: Prasanna Deshmukh Affiliation: Indian Institute of Astrophysics Conference ID: ASI2015_464 Title : Dynamic loading assembly for performance testing of Segmented Mirror Telescope Actuators. Authors and Co-Authors : Padmakar Parihar, Indian Institute of Astrophysics, Bangalore. Karthik AB, Christ University, Bangalore. Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : Upcoming Extremely large telescopes are 20-40 meter class and are based on segmented mirror technology. Hexagonal Segments in the range of 1 meter size placed side by side forms the 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. The actuator along with a controller is required to meet very stringent performance requirements, such as track rates up to 300 nm/sec with tracking errors less than 4.4nm, dynamical forces of up to +/-40 N, ability to reject disturbances introduced by wind as well as by mechanical vibration generated in the mirror cell etc. Actuators required for upcoming segmented mirror telescopes (SMT) like TMT and E-ELT are being developed and required to go through various performance tests. In order to conduct these performance tests in more realistic conditions, we have designed and developed a Dynamic Loading Assembly (DLA) at ITCC Laboratory of Indian Institute of Astrophysics, Bangalore. Our DLA is a computer controlled force inducing device designed in a modular fashion to ease the design of experiment and can generate different type of user defined disturbances in extremely smooth and controlled manner. A simple spring-mass-damper based mathematical model developed by us, helped to ensure that the concept will work. Then after a detailed mechanical design work was undertaken, by making use of SolidWorks software and components were manufactured in IIA workshop. DLA have static and dynamic loading capability up to 250N and 18N respectively, with the bandwidth greater than 10 Hz. In this paper we will discuss various performance requirements of a SMT Actuator and our efforts to develop DLA at ITCC Laboratory of Indian Institute of Astrophysics, Bangalore. We will also discuss different test results obtained using DLA and a prototype actuator, developed for the Thirty Meter Telescope project. |