Combined integral and robust control of the segmented mirror telescope

Abstract

Future space telescopes must maintain lower mass of the mirrors to keep launch cost down while increasing the size and performance of the space telescope. Although much work has been done in both adaptive optics and robust control, this thesis explores the application of several Multi-Input, Multi-Output controller designs for wavefront control of a Segmented Mirror Telescope with 936 actuators and 732 sensors. This thesis builds on previous robust control design by combining classical control with an H (Infinity) robust controller on a Singular Value Decomposition reduced model. It also presents reduction using Zernike polynomials and applies it to the integral control model as an alternate to Singular Value Decomposition model reduction. All methods were able to meet the 10 Hz bandwidth by design. Therefore, the analysis shows that there are several trade-offs that can be made based on control system size and desired performance. The H (Infinity) controller is combined in parallel with the integral controller for this thesis. The analysis shows that the parallel combined controller outperforms all other controllers; however, the cost analysis shows that a simpler Zernike reduced model can achieve slightly reduced performance at a much lower cost.