This paper introduces an innovative robust and nonlinear control design methodology for high-performance servosystems in optical telescopes. The dynamics of optical telescopes typically vary according to azimuth and altitude angles, temperature, friction, speed and acceleration, leading to nonlinearities and plant parameter uncertainty. The methodology proposed in this paper combines robust Quantitative Feedback Theory (QFT) techniques with nonlinear switching strategies that achieve simultaneously the best characteristics of a set of very active (fast) robust QFT controllers and very stable (slow) robust QFT controllers. A general dynamic model and a variety of specifications from several different commercially available amateur Newtonian telescopes are used for the controller design as well as the simulation and validation. It is also proven that the nonlinear/switching controller is stable for any switching strategy and switching velocity, according to described frequency conditions based on common quadratic Lyapunov functions (CQLF) and the circle criterion.

Date Published: 18 July 2014
PDF: 14 pages
Proc. SPIE 9152, Software and Cyberinfrastructure for Astronomy III, 91521F (18 July 2014); doi: 10.1117/12.2056910

Published in SPIE Proceedings Vol. 9152:
Software and Cyberinfrastructure for Astronomy III
Gianluca Chiozzi; Nicole M. Radziwill, Editor(s)