The control problem examined is to stablize a large, spaceborne Cassegrain telescope. Modal gain factors and known characteristics of disturbances are used to determine which structural modes affect line-of-sight (LOS) the most and are candidates for active control. The approach is then to: (0 actively control/maintain alignment of optical components; (ii) place structural control actuators for optimum impact on the selected modes for active vibration control; (iii) feed back the best available estimate of LOS error for direct LOS control. Local analog loops are used for high BW control; multi-variable digital control for lower BW control. The control law is synthesized in the frequency domain using the charac-teristic gain approach. Robustness is measured by employing conicity, which is an outgrowth of the positivity approach to robust feedback system design.

Date Published: 3 June 1987
PDF: 12 pages
Proc. SPIE 0748, Structural Mechanics of Optical Systems II, (3 June 1987); doi: 10.1117/12.939824

Published in SPIE Proceedings Vol. 0748:
Structural Mechanics of Optical Systems II
Alson E. Hatheway, Editor(s)