22 July 2014 The integrated motion measurement simulation for SOFIA
Author Affiliations +
Abstract
The Stratospheric Observatory for Infrared Astronomy SOFIA consists of a B747-SP aircraft, which carries aloft a 2.7-meter reflecting telescope. The image stability goal for SOFIA is 0:2 arc-seconds rms. The performance of the telescope structure is affected by elastic vibrations induced by aeroacoustic and suspension disturbances. Active compensation of such disturbances requires a fast way of estimating the structural motion. Integrated navigation systems are examples of such estimation systems. However they employ a rigid body assumption. A possible extension of these systems to an elastic structure is shown by different authors for one dimensional beam structures taking into account the eigenmodes of the structural system. The rigid body motion as well as the flexible modes of the telescope assembly, however, are coupled among the three axes. Extending a special mathematical approach to three dimensional structures, the aspect of a modal observer based on integrated motion measurement is simulated for SOFIA. It is in general a fusion of different measurement methods by using their benefits and blinding out their disadvantages. There are no mass and stillness properties needed directly in this approach. However, the knowledge of modal properties of the structure is necessary for the implementation of this method. A finite-element model is chosen as a basis to extract the modal properties of the structure.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Prashant Kaswekar, Prashant Kaswekar, Benjamin Greiner, Benjamin Greiner, Jörg Wagner, Jörg Wagner, } "The integrated motion measurement simulation for SOFIA", Proc. SPIE 9145, Ground-based and Airborne Telescopes V, 91454F (22 July 2014); doi: 10.1117/12.2054900; https://doi.org/10.1117/12.2054900
PROCEEDINGS
15 PAGES


SHARE
Back to Top