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Proceedings Paper

A nonlinear disturbance-decoupled elevation axis controller for the Multiple Mirror Telescope
Author(s): Dusty Clark; Tom Trebisky; Keith Powell
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Paper Abstract

The Multiple Mirror Telescope (MMT), upgraded in 2000 to a monolithic 6.5m primary mirror from its original array of six 1.8m primary mirrors, was commissioned with axis controllers designed early in the upgrade process without regard to structural resonances or the possibility of the need for digital filtering of the control axis signal path. Post-commissioning performance issues led us to investigate replacement of the original control system with a more modern digital controller with full control over the system filters and gain paths. This work, from system identification through controller design iteration by simulation, and pre-deployment hardware-in-the-loop testing, was performed using latest-generation tools with Matlab® and Simulink®. Using Simulink's Real Time Workshop toolbox to automatically generate C source code for the controller from the Simulink diagram and a custom target build script, we were able to deploy the new controller into our existing software infrastructure running Wind River's VxWorks™real-time operating system. This paper describes the process of the controller design, including system identification data collection, with discussion of implementation of non-linear control modes and disturbance decoupling, which became necessary to obtain acceptable wind buffeting rejection.

Paper Details

Date Published: 21 July 2008
PDF: 11 pages
Proc. SPIE 7019, Advanced Software and Control for Astronomy II, 70192J (21 July 2008); doi: 10.1117/12.793287
Show Author Affiliations
Dusty Clark, Multiple Mirror Telescope Observatory, Univ. of Arizona (United States)
Tom Trebisky, Multiple Mirror Telescope Observatory, Univ. of Arizona (United States)
Keith Powell, Steward Observatory Ctr. for Astronomical Adaptive Optics, Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 7019:
Advanced Software and Control for Astronomy II
Alan Bridger; Nicole M. Radziwill, Editor(s)

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