Centralized, decentralized, and overlapping control designs for a segmented telescope

Abstract

The accurate control of the segments of large segmented telescopes to achieve the desired shape could open the way for the construction of much larger telescopes with much better capabilities. In this article, we consider the centralized, decentralized and overlapping approaches to designing controllers for shape control of a segmented telescope. In each case, we design controllers using the H∞ robust control approach. In the centralized control case, the disturbances are rejected over a wide frequency range and all performance requirements are met. The order of the centralized controller, however, is high, which makes it difficult to implement in real time. The decentralized control approach greatly reduces the computational and hardware requirements at the expense of performance deterioration. The overlapping approach is shown to be a tradeoff between the centralized and decentralized one and provides sufficient flexibility to meet both performance and computational requirements.